Method and system for detecting a USB sound playing device

Abstract

The application provides a detection method and system based on a USB sound playing device, capability description data, transmission configuration data and channel configuration data of a USB audio device to be detected are acquired; when the capability description data lacks valid capability information of a target audio format, theoretical transmission capability and device data requirements of each capability level are determined, and a candidate capability sequence is established by comparison; current candidate capability is selected and test audio data is transmitted, and whether the test audio data passes verification is determined according to verification state data; if not, test transmission strategy is adjusted, current candidate capability is kept and re-verification is performed, and if the test audio data still does not pass verification, the next candidate capability is verified; verification capability is determined according to the verification result, and audio capability record is corrected, so that the record corresponds to data channel transmission capability verified under current test connection conditions.

Description

Technical Field

[0001] This invention relates to the field of detection technology for USB audio playback devices, and more particularly to a detection method and system for USB audio playback devices. Background Technology

[0002] After a USB audio device is connected to the host, the host reads the device descriptor, audio control interface description information, and audio stream interface description information during the device enumeration phase, obtaining information such as device type, audio interface, transmission endpoint, number of channels, and audio format. Based on the read capability description data, the host configures the audio stream interface and transmission endpoint, and then sends audio data to the USB audio device according to the corresponding audio format. Device detection programs typically follow the above identification process, using the capability description data as the primary basis for determining the device's audio capabilities and arranging subsequent testing items.

[0003] The capability description data of a USB audio device reflects the device's declared capabilities. For audio formats such as PCM, which are described according to the USB audio class specification, the host can read the format, sampling parameters, and channel configuration from the audio stream interface description information. For audio formats such as DSD, which use manufacturer extensions, dedicated drivers, or specific data organization methods for transmission, some devices do not fully declare the corresponding transmission methods and capability levels in their capability description data; some devices, although declaring relevant capabilities, may have incomplete correspondences or inconsistent capability levels between different descriptions. When the device firmware version, driver adaptation method, and interface implementation change, the declared information and actual transmission capabilities of the same model of device may also differ. Therefore, the lack of valid capability information for the target audio format in the capability description data does not directly indicate that the device lacks the corresponding audio transmission capabilities.

[0004] The transmission configuration data of an audio stream endpoint reflects the carrying capacity of the USB data path. For example, the amount of data the endpoint is allowed to carry in a single transmission cycle, the frequency of data transmission, and the number of audio channels collectively limit the amount of audio data that can be transmitted per unit time. Different audio formats and different capability levels have different data requirements, and the amount of data required for the same capability level also differs in mono, stereo, or multi-channel configurations. Existing testing methods typically do not combine transmission configuration data and channel configuration data to screen the candidate capability range of the target audio format. Instead, they directly conduct testing based on device declaration information, the preset capabilities corresponding to the device model, or fixed test levels. When device declaration information is missing, preset capabilities do not correspond to the current firmware, or fixed test levels exceed the endpoint's carrying capacity, the test results are prone to deviating from the actual situation of the device.

[0005] Some testing programs send test audio data in a preset format to the device and determine whether the device supports the corresponding capability based on whether the test audio data can be transmitted. In actual testing, the transmission status of test audio data is not only limited by the device's capabilities but also related to the test transmission strategy. Incomplete configuration of the audio stream interface, the target endpoint not entering the transmission state, a mismatch between the data submission rhythm and the endpoint transmission cycle, underloading or overflow of the data buffer, and a mismatch between the audio data organization method and the device's receiving method can all cause pauses, interruptions, insufficient effective transmission volume, or format loss in the test audio data. In such cases, even if the device itself possesses the current capability level, it will still receive a result indicating that the current level of verification has failed.

[0006] Current testing procedures, upon failing verification at the current capability level, typically record that level as unsupported or switch to a lower level for testing, without considering the status data during transmission to determine the cause of the failure, or adjusting the test transmission strategy and re-verifying while maintaining the current candidate capability. Verification failures caused by abnormal transmission configurations are attributed to insufficient device capability, resulting in a final determined capability level lower than the actual capability level the device can achieve. Furthermore, transmission configuration data reflects the theoretical carrying capacity of the data path. Even if the theoretical carrying capacity meets the data requirements of a certain audio format, it does not directly prove that the device's internal audio processing path supports that format; confirmation based on actual transmission results is still necessary. Summary of the Invention

[0007] In view of this, it is necessary to provide a detection method and system based on USB audio playback devices to solve the problem that existing detection methods do not combine theoretical transmission capacity, actual transmission status and transmission configuration anomalies to determine device capabilities when the capability description data lacks effective capability information of the target audio format, which can easily lead to capability level identification errors.

[0008] Embodiments of this application provide a detection method based on a USB audio playback device, including: Obtain the capability description data, transmission configuration data, and channel configuration data of the USB audio device under test; When the capability description data lacks valid capability information for the target audio format, the theoretical transmission capability is determined by the transmission configuration data, the device data requirements are determined according to the capability levels of the target audio format and the channel configuration data, the two are compared and a candidate capability sequence is established. Select the current candidate capability, generate a test transmission strategy, and control the USB audio device under test to transmit test audio data; Determine whether the current candidate capability has passed verification based on the verification status data; If the test fails, adjust the test transmission strategy based on the verification status data and re-verify the current candidate capability; if it still fails, verify the next candidate capability. The verification capability is determined based on the verification results, and the audio capability record of the USB audio device under test is corrected.

[0009] In at least one embodiment of this application, the target audio format is DSD audio format, the capability description data includes a USB device descriptor, audio control interface description information and audio stream interface description information, and the effective capability information includes DSD transmission mode and DSD capability level; If the DSD transmission method is not obtained, the DSD capability level is not obtained, or the obtained DSD transmission method does not correspond to the DSD capability level, it is determined that the capability description data lacks the valid capability information.

[0010] In at least one embodiment of this application, the USB bus speed is full speed or high speed, the transmission configuration data includes the maximum packet information of the audio stream endpoint, the endpoint polling interval and the USB bus speed, and the channel configuration data includes the number of audio channels; The data carrying capacity of the audio stream endpoint in a single transmission cycle is determined based on the endpoint maximum packet information. The data transmission frequency per unit time is determined based on the endpoint polling interval and the USB bus speed. The theoretical data transmission volume is determined based on the data carrying capacity and the data transmission frequency, and the theoretical data transmission volume is used as the theoretical transmission capacity.

[0011] In at least one embodiment of this application, the device data requirements of each DSD capability level under each available audio data encapsulation method are determined according to the effective data requirements of each mono channel of different DSD capability levels, the number of audio channels, and the encapsulation overhead corresponding to the available audio data encapsulation method. DSD capability levels with at least one device data requirement not exceeding the theoretical data transmission volume are added to the candidate capability sequence and arranged from high to low according to the DSD capability level. The DSD capability level at the top of the candidate capability sequence is determined as the current candidate capability for the first verification.

[0012] In at least one embodiment of this application, the test transmission strategy includes an audio stream interface corresponding to the current candidate capability, interface alternative settings, target audio stream endpoint, audio data encapsulation method, data submission rhythm, data buffer capacity, and preset verification duration; The verification status data includes interface configuration status, endpoint startup status, data transmission continuity status, effective data transmission volume, data cache status, and audio format preservation status. When the audio stream interface is configured, the target audio stream endpoint enters the transmission state, the test audio data is continuously transmitted within the preset verification duration, the effective transmission data volume is not less than the product of the device data requirement of the current candidate capability under the currently adopted audio data encapsulation method and the preset verification duration, the data cache state is within the preset working range, and the test audio data maintains the corresponding audio format, it is determined that the current candidate capability meets the verification conditions.

[0013] In at least one embodiment of this application, adjusting the test transmission strategy based on the verification status data includes: When the interface configuration status is abnormal, switch the alternative interface settings for the audio stream interface and reconfigure the audio stream interface; If the endpoint startup state is abnormal, the target audio stream endpoint will be reinitialized. When the data transmission continuity is abnormal or the data buffer state is not within the preset working range, adjust the data submission rhythm and / or the data buffer capacity. When the audio format preservation state is abnormal, the audio data encapsulation method is switched; The current candidate capability is maintained according to the adjusted test transmission strategy, and transmission verification is performed again.

[0014] In at least one embodiment of this application, if the current candidate capability still does not meet the verification conditions after adjusting the test transmission strategy, the next DSD capability level in the candidate capability sequence is determined as the new current candidate capability, and transmission verification is performed sequentially from high to low according to the candidate capability sequence. The first DSD capability level that meets the verification conditions is determined as the verified capability. If none of the DSD capability levels meet the verification conditions, the audio capability record is corrected to show that the DSD transmission capability has not been verified.

[0015] In at least one embodiment of this application, equalization processing verification items are determined based on the corrected audio capability record, input audio data before equalization processing and output audio data after equalization processing are obtained within the same audio processing time period, frequency domain features of the input audio data and the output audio data in multiple frequency ranges are extracted respectively to form the spectral change distribution before and after equalization processing, and the spectral change distribution is compared with the preset spectral change features corresponding to the equalization processing parameters to determine the equalization processing result.

[0016] In at least one embodiment of this application, device function testing items are determined based on corrected audio capability records, the device function testing items including: When the audio capability record includes an audio input channel, the microphone input status is determined based on the microphone input data corresponding to the audio input channel. The channel output detection items are determined based on the number of output channels in the audio capability record, channel test data is transmitted to different audio output channels respectively, and the channel output status is determined based on the test confirmation information. When the USB audio device under test has interactive input function, the button response state is determined based on the button information reported by the USB audio device under test in response to physical button operation. The device parameters of the USB audio device under test are compared with the reference device parameters of a standard USB audio device to form a device parameter comparison result. The device function test result is generated based on the microphone input status, the channel output status, the button response status, and the device parameter comparison result.

[0017] A detection system based on a USB audio playback device includes a data acquisition module, a storage module, and a processing module; The data acquisition module includes a USB communication interface for connecting to the USB audio device under test, acquiring the capability description data, transmission configuration data, channel configuration data and verification status data of the USB audio device under test, and transmitting test audio data to the USB audio device under test. The storage module is used to store device data requirements, test audio data, audio capability records, and computer programs at different capability levels. The processing module is used to run the computer program to perform the detection method for USB audio playback devices described in any of the above-described methods.

[0018] The detection method and system for USB audio playback devices implemented in this embodiment will have at least the following beneficial effects: The aforementioned detection method and system for USB audio playback devices acquires capability description data, transmission configuration data, and channel configuration data of the USB audio device under test. When the capability description data lacks valid capability information for the target audio format, the theoretical transmission capability is determined based on the transmission configuration data. The device data requirements are determined according to the capability levels of the target audio format and the channel configuration data. A candidate capability sequence is established by comparing the theoretical transmission capability with each device data requirement, so that the device capability detection has a verification range corresponding to the current data transmission conditions.

[0019] During the testing process, a test transmission strategy is generated according to the current candidate capabilities and test audio data is transmitted. The verification status data during the transmission process is used to determine whether the current candidate capability meets the verification conditions. If the current candidate capability does not meet the verification conditions, the candidate capability is maintained and the test transmission strategy is adjusted for re-verification. If the verification conditions are still not met after adjustment, the next candidate capability is verified, so that test transmission strategy abnormalities and insufficient equipment capabilities are handled in stages.

[0020] Finally, based on the verification results, the verification capability is determined and the audio capability record is corrected so that the corrected audio capability record corresponds to the data path transmission capability verified by the USB audio device under test under the current test connection conditions, thereby improving the accuracy of the device audio capability test results. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] in: Figure 1 This is a flowchart of a detection method based on a USB audio playback device in one embodiment; Figure 2 This is a flowchart of the detection method for USB audio playback devices in Example 2; Figure 3 This is a structural block diagram of a detection system based on a USB audio playback device in one embodiment.

[0023] Explanation of key component symbols: 100. Detection system based on USB audio playback device; 110. Data acquisition module; 120. Storage module; 130. Processing module. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1: This example provides a method for detecting a USB audio device, including: Step S101: Obtain the capability description data, transmission configuration data, and channel configuration data of the USB audio device under test.

[0026] The USB audio device under test refers to the USB device currently undergoing audio transmission capability testing. During testing, the USB audio device under test is connected to the testing host, which is a computer running the testing program, an embedded testing terminal, or other device with USB host functionality.

[0027] Capability description data refers to the data provided by the USB audio device under test to the testing host to declare the device's audio capabilities, including supported audio formats, capability levels, and audio interface information. Transmission configuration data reflects the carrying capacity of the USB audio data path, including the amount of data allowed per transmission cycle, the number of transmissions per unit time, and available transmission paths. Channel configuration data reflects the number of audio channels, channel direction, and channel arrangement.

[0028] The testing host reads the above data during the USB enumeration process and saves the reading results along with the device identifier of the USB audio device under test, so that the verification results obtained later can be written into the audio capability record of the same device.

[0029] Step S102: Determine whether the capability description data lacks valid capability information for the target audio format.

[0030] The target audio format refers to the audio format that needs to be confirmed in this test, such as DSD audio format or other audio formats with multiple transmission capability levels. Effective capability information refers to information that clearly determines the transmission method and supported capability level of the USB audio device under test for the target audio format.

[0031] When the detection host fails to read the transmission method of the target audio format, fails to read the corresponding capability level, or fails to read the effective correspondence between the read transmission method and capability level, it determines that the capability description data lacks effective capability information for the target audio format and enters the capability derivation and transmission verification process.

[0032] Step S103: Determine the theoretical transmission capacity based on the transmission configuration data, determine the device data requirements based on the capability levels and channel configuration data of the target audio format, compare the theoretical transmission capacity with the data requirements of each device, and establish a candidate capability sequence based on the comparison results.

[0033] Theoretical transmission capacity refers to the upper limit of data carrying capacity per unit time calculated according to the transmission configuration of the USB data path. It is used to determine the basic transmission capability level of the USB audio device under test under the current connection conditions. Theoretical transmission capacity is used to screen the verification range, and the final capability is still subject to the actual transmission verification results.

[0034] Let B be the data capacity of a single transmission cycle, and F be the number of transmissions per unit time. Then, the theoretical data transmission volume Q per unit time is calculated as the product of B and F. Taking a single transmission cycle capable of carrying 1024 bytes and performing 8000 transmissions per second as an example, the theoretical data transmission volume is: Q = 1024 × 8000 = 8192000 bytes / second.

[0035] For any capability level of the target audio format, first determine the single-channel data requirement for that capability level, then multiply it by the number of channels and the corresponding data encapsulation factor to obtain the device data requirement. Taking a dual-channel device as an example, the device data requirements for the three capability levels are 5,644,800 bytes / second, 2,822,400 bytes / second, and 1,411,200 bytes / second, respectively, all less than 8,192,000 bytes / second. Therefore, all three capability levels have corresponding theoretical transmission conditions.

[0036] A candidate capability sequence refers to a verification set formed by arranging the capability levels that can be covered by the theoretical data transmission volume in a predetermined order. In this embodiment, the capability levels are arranged from high to low according to the device data requirements, forming a candidate capability sequence consisting of a first capability level, a second capability level, and a third capability level. Capability levels whose device data requirements exceed the theoretical data transmission volume are not included in this sequence.

[0037] Step S104: Select the current candidate capability, generate a test transmission strategy, and control the USB audio device under test to transmit test audio data.

[0038] The current candidate capability refers to the capability level currently undergoing transmission verification in the candidate capability sequence. During the initial verification, the detection host determines the first capability level with the highest data demand in the candidate capability sequence as the current candidate capability.

[0039] The test transmission strategy refers to the audio data transmission configuration determined by the testing host for the current candidate capability, including the audio stream interface, interface alternative settings, target audio stream endpoint, audio data encapsulation method, data submission rhythm, data buffer capacity, and preset verification duration. Test audio data refers to audio data with a defined format and volume used to verify the current candidate capability.

[0040] In this embodiment, the verification duration is set to two seconds. The data requirement corresponding to the first capability level is 5,644,800 bytes / second. Therefore, the amount of test audio data that needs to be transmitted during the two-second verification period is: 5644800 × 2 = 11289600 bytes.

[0041] The testing host continuously generates test audio data according to the data rate corresponding to the current candidate capability, and submits the test audio data to the USB audio device under test according to the test transmission strategy.

[0042] Step S105: Determine whether the current candidate capability meets the verification conditions based on the verification status data being transmitted.

[0043] Verification status data refers to data generated during the test audio data transmission process that reflects the transmission configuration and data transmission results, including interface configuration status, endpoint startup status, data transmission continuity status, effective transmitted data volume, data buffer status, and audio format preservation status.

[0044] Verification conditions refer to the combination of states required to confirm that the current candidate capability is valid. In this embodiment, the first capability level is determined to meet the verification conditions when the audio stream interface is configured, the target audio stream endpoint enters the transmission state, the test audio data is continuously transmitted within the two-second verification period, the effective transmission data volume reaches 11,289,600 bytes, the data cache state is within the preset working range, and the audio format remains consistent.

[0045] The effective data transmission volume is calculated by adding up the audio payloads of each successfully transmitted data transmission within the verification period. Data transmissions that are abnormal, canceled, or incomplete are not included in the effective data transmission volume.

[0046] Step S106: If the current candidate capability does not meet the verification conditions, adjust the test transmission strategy according to the verification status data and re-verify the current candidate capability.

[0047] Adjusting the test transmission strategy involves correcting the corresponding transmission configuration based on anomalies reflected in the verification status data. During the adjustment period, the current candidate capabilities remain unchanged to distinguish between transmission configuration anomalies and insufficient equipment capabilities.

[0048] For example, if the data rate corresponding to the first capability level is 5,644,800 bytes / second and the initial buffer duration is 10 milliseconds, then the initial buffer capacity is: 5,644,800 × 10 ÷ 1000 = 56,448 bytes.

[0049] When the verification status data shows that the data submission is interrupted, the buffer duration will be adjusted to 20 milliseconds. The adjusted buffer capacity is: 5644800×20÷1000=112896 bytes.

[0050] The testing host reorganizes the test audio data according to a buffer capacity of 112,896 bytes and still performs a two-second transmission verification at the first capability level.

[0051] If the adjusted effective data transmission volume still does not reach 11,289,600 bytes, or the audio format is still not maintained, it is determined that the first capability level still does not meet the verification conditions after adjustment. The detection host then selects the second capability level from the candidate capability sequence as the new current candidate capability.

[0052] The data requirement for the second capability level is 2,822,400 bytes / second. The data requirement for the two-second verification period is 2,822,400 × 2 = 5,644,800 bytes.

[0053] The testing host regenerates the test transmission strategy according to the second capability level and transmits the test audio data. When the effective data transmission volume reaches 5,644,800 bytes within two seconds, and all other verification states meet the requirements, the second capability level is determined to have met the verification conditions.

[0054] Step S107: Determine the verification capability based on the verification result, and correct the audio capability record of the USB audio device under test accordingly.

[0055] The verification result refers to the record of whether or not the verification conditions are met after each candidate capability has undergone transmission verification. The verified capability refers to the highest capability level that meets the verification conditions after actual transmission verification. In this embodiment, the first capability level does not meet the verification conditions, while the second capability level does. Therefore, the second capability level is determined as the verified capability.

[0056] Audio capability records refer to the data stored by the testing system for the USB audio device under test, which records the target audio format, verification capabilities, audio data encapsulation method used for verification, audio input channels, number of output channels, and verification anomaly information. Correcting the audio capability record means updating the testing record corresponding to the USB audio device under test in the testing system, excluding rewriting the USB descriptor, device firmware, or hardware configuration of the USB audio device under test. The testing host writes the target audio format, second capability level, and the transmission configuration used during verification into the audio capability record, completing the correction of the original audio capability record. When testing the same device subsequently, the testing host reads the corrected audio capability record and arranges the corresponding testing items according to the verified capability level.

[0057] Available audio data encapsulation methods refer to data encapsulation methods that can be configured and used for transmission verification based on the interface alternative settings, audio format, sub-time slot length, and effective bit length in the audio stream interface description information. Encapsulation overhead refers to the amount of transmitted data added due to format tags, padding bytes, or sub-time slot extensions, in addition to the effective audio data of the target audio format. This encapsulation overhead is represented by an encapsulation coefficient N.

[0058] Let R be the effective data requirement for a single channel at a certain capability level, and C be the number of audio channels. Then, the device data requirement D for that capability level under the corresponding audio data encapsulation method is calculated as D = R × C × N. The encapsulation factor N is 1 for native DSD transmission; 3 / 2 for DoP transmission with three-byte sub-timeslots; and 2 for DoP transmission with four-byte sub-timeslots.

[0059] Example 2: The USB audio device under test is a dual-channel USB decoding device using high-speed USB transmission, and the target audio format is DSD audio format. DSD audio format refers to an audio format that represents audio signals using a one-bit data stream, and its capability levels include DSD64, DSD128, and DSD256. The specific interface number, endpoint address, and data parameters in this example are used to illustrate the testing process; in actual applications, they should be determined according to the interface information provided by the device under test.

[0060] Step S201: The detection host reads the USB device descriptor, audio control interface description information and audio stream interface description information during the enumeration of the USB audio device under test.

[0061] The USB device descriptor is data used to record the device vendor identifier, product identifier, device version, and USB protocol version. The audio control interface description information is data used to record the audio functional units, audio terminals, clock source, and channel organization. The audio stream interface description information is data used to record the audio stream interface, interface alternative settings, audio format, sub-slot length, effective bits, and audio stream endpoints. At least one of the above data constitutes the capability description data of this embodiment.

[0062] The detection host simultaneously reads transmission configuration data and channel configuration data. The transmission configuration data includes the maximum packet size of the audio stream endpoints, the endpoint polling interval, and the USB bus speed. The maximum packet size indicates the data capacity of a single transaction and the number of transactions within a transmission cycle; the endpoint polling interval indicates the time interval between two adjacent endpoint services; and the USB bus speed determines the time unit used for the endpoint service interval. The channel configuration data includes the number of audio output channels; in this embodiment, the number of audio output channels is two.

[0063] DSD transmission method refers to the way DSD data is organized in a USB audio data stream, including native DSD transmission method and DSD over PCM transmission method. DSD over PCM transmission method, abbreviated as DoP, refers to the transmission method that loads valid DSD data into PCM format data frames and sets format markers in the data frames.

[0064] The testing host did not simultaneously retrieve a clear DSD transmission method and DSD capability level from the capability description data, therefore determining that the capability description data lacked valid capability information for the DSD audio format. In other testing scenarios, if the DSD transmission method and DSD capability level declared in the capability description data contradicted each other—for example, if the declared interface data rate only covered DSD128, but the capability information also declared support for DSD256—it was also treated as lacking valid capability information.

[0065] Step S202: Detect the maximum packet information of the endpoint of the host parsing the audio stream endpoint.

[0066] In this embodiment, the maximum packet information of the endpoint is 0x0400. A bitwise AND operation is performed between 0x0400 and 0x07FF, resulting in the lower eleven bits of the value 0x0400, indicating that a single data transaction can carry 1024 bytes of data. 0x0400 is then right-shifted eleven bits and bitwise ANDed with 0x03, resulting in a transaction count field of zero. The actual transaction count is determined by adding one to this field value; therefore, one data transaction is executed per transmission cycle. The data carrying capacity of a single transmission cycle is 1024 × 1 = 1024 bytes.

[0067] When the audio stream endpoint is a USB high-speed high-bandwidth endpoint, and the maximum packet information of the endpoint is 0x1400, its lower eleven bits are 1024, and the transaction quantity field is two, indicating that each microframe is allowed to execute three data transactions. Therefore, the data carrying capacity of a single microframe is 1024×3=3072 bytes.

[0068] In this embodiment, the USB bus speed is high-speed, and USB high-speed transmission uses 125 microseconds as a microframe. The endpoint polling interval is one, and the endpoint service interval is calculated as 2 raised to the power of "endpoint polling interval minus one" multiplied by 125 microseconds, that is: 2^(1-1)×125=125 microseconds.

[0069] The data transmission frequency per second is: 1,000,000 ÷ 125 = 8,000 times / second.

[0070] Therefore, the theoretical data transmission volume of this audio stream endpoint is: 1024 × 8000 = 8192000 bytes / second.

[0071] When the endpoint polling interval is two, the endpoint service interval is 250 microseconds, and the data transmission frequency per second is 4000 times. For USB full-speed isochronous endpoints, a one-millisecond bus frame is used as the time unit; the endpoint service interval is determined according to 2 raised to the power of "endpoint polling interval - one" bus frames, and the data transmission frequency per unit time is calculated based on the endpoint service interval. The above calculation applies to USB full-speed or high-speed isochronous endpoints; for SuperSpeed ​​endpoints, the data capacity of a single service interval should be determined in conjunction with the endpoint accompanying description information.

[0072] Step S203: Calculate the mono data requirements and stereo device data requirements for each DSD capability level.

[0073] The DSD64 mono data rate is 2,822,400 bits per second, and each byte contains eight bits. Therefore, its mono data requirement is: 2,822,400 ÷ 8 = 352,800 bytes per second.

[0074] The data requirement for native DSD64 in two channels is: 352800 × 2 = 705600 bytes / second.

[0075] The DSD128 has a mono data rate of 5,644,800 bits / second, a mono data requirement of 705,600 bytes / second, and a stereo data requirement of 1,411,200 bytes / second.

[0076] The DSD256 has a mono data rate of 11,289,600 bits / second, a mono data requirement of 1,411,200 bytes / second, and a stereo data requirement of 2,822,400 bytes / second.

[0077] When using DoP transmission, each 24-bit audio sample contains 16 bits of valid DSD data and 8 bits of format markers. The corresponding PCM frame rate for DSD64 is: 2,822,400 ÷ 16 = 176,400 frames per second.

[0078] When the sub-timeslot length of one channel is three bytes, the data requirement of dual-channel DoP DSD64 is: 176400×3×2=1058400 bytes / second.

[0079] Correspondingly, the data requirements for the dual-channel DoP DSD128 and DoP DSD256 are 2,116,800 bytes / second and 4,233,600 bytes / second, respectively.

[0080] The audio stream interface in this embodiment uses a four-byte sub-timeslot, with each audio sample from each channel transmitted in four-byte increments. The data requirement for dual-channel DoP DSD64 is: 176400 × 4 × 2 = 1411200 bytes / second.

[0081] The data requirement of the dual-channel DoP DSD128 is: 352800 × 4 × 2 = 2822400 bytes / second.

[0082] The data requirement of the dual-channel DoP DSD256 is: 705600 × 4 × 2 = 5644800 bytes / second.

[0083] The testing host compared the device data requirements of each DSD capability level under both native DSD and DoP transmission modes with 8,192,000 bytes / second. Since DSD64, DSD128, and DSD256 all have at least one audio data encapsulation method where the device data requirement does not exceed the theoretical transmission data volume, the three DSD capability levels were added to the candidate capability sequence and arranged in the order of DSD256, DSD128, and DSD64. DSD256 was determined as the current candidate capability for initial verification.

[0084] Step S204: The detection host generates a test transmission strategy based on DSD256.

[0085] The audio stream interface refers to the interface in a USB audio device used to carry continuous audio data. In this embodiment, the native DSD interface with interface number two and alternative setting two is selected first, and the output endpoint 0x01 corresponding to this interface is used as the target audio stream endpoint. The target audio stream endpoint refers to the USB endpoint to which the current test audio data is actually submitted.

[0086] The audio data encapsulation method refers to the arrangement of test audio data in the USB audio sample. The test host first organizes the test audio data according to the native DSD transmission method, while reserving the DoP transmission configuration with interface number two and alternative setting three as a backup transmission method for format adjustment.

[0087] The native dual-channel DSD256 requires 2,822,400 bytes to be transmitted per second, and the endpoint receives 8,000 services per second. Therefore, the average data volume per service interval is: 2,822,400 ÷ 8,000 = 352.8 bytes.

[0088] Native DSD data is arranged in data units consisting of one byte for each of the two channels, with each data unit being two bytes. Therefore, each service interval transmits 176 or 177 data units, which is 352 or 354 bytes. A total of 352.8 × 5 = 1764 bytes need to be transmitted over five consecutive service intervals.

[0089] The detection host schedules three 352-byte data packets and two 354-byte data packets across five service intervals, resulting in a total data volume of 1764 bytes across the five service intervals. The detection host continuously determines the data packet length for each service interval using a remainder accumulation method, ensuring that the cumulative transmission volume over a long period matches the data requirements of DSD256.

[0090] The verification duration is set to two seconds. The target data volume of native DSD256 within two seconds is: 2822400×2=5644800 bytes.

[0091] The initial buffer duration is set to 10 milliseconds, and the initial buffer capacity of the native DSD256 is: 2822400×10÷1000=28224 bytes.

[0092] Before starting the target audio stream endpoint, the detection host first writes 28224 bytes of test audio data to the data buffer, and then continuously replenishes the data according to the endpoint service interval.

[0093] When the transmission mode is switched to DoP DSD256 with four-byte sub-slots, each dual-channel PCM data frame occupies eight bytes, and the PCM frame rate is 705,600 frames / second. The average number of frames per endpoint service interval is: 705,600 ÷ 8,000 = 88.2 frames.

[0094] The detection host submitted 88 frames (704 bytes) in each of the first four service intervals, and 89 frames (712 bytes) in the fifth service interval. The total data volume across the five service intervals is 704 × 4 + 712 = 3528 bytes. This value is consistent with the calculation result of 5644800÷8000×5.

[0095] Step S205: The detection host configures the audio stream interface according to the test transmission strategy, starts the target audio stream endpoint and transmits test audio data, and collects verification status data at the same time.

[0096] The interface configuration status refers to whether the audio stream interface has entered the candidate settings corresponding to the current candidate capability. The detection host determines the interface configuration status based on the execution result of the interface candidate setting request and the interface status reading result.

[0097] Endpoint startup status refers to whether the target audio stream endpoint has completed initialization and started receiving continuous transmission requests. The detection host makes this judgment based on the endpoint initialization result and the transmission request completion status.

[0098] Data transmission continuity refers to whether the test audio data is continuously submitted within the verification period, corresponding to the endpoint service interval. The two-second verification period includes 8000 × 2 = 16000 endpoint service intervals.

[0099] The detection host checks whether the data corresponding to the above 16,000 service intervals has been submitted, and checks whether any unplanned stops occurred during transmission.

[0100] The effective data transmission volume refers to the total amount of audio payload that was successfully transmitted within the verification period. Let Li be the actual audio payload of the i-th successful transmission, and there be n successful transmissions. The effective data transmission volume is obtained by adding L1 to Ln sequentially. USB protocol headers, data from execution errors, and incomplete data are not included in the effective data transmission volume.

[0101] The data buffer status indicates the real-time occupancy, minimum occupancy, maximum occupancy, and whether underloading or overflow has occurred after the target audio stream endpoint begins transmission. Let the data buffer capacity be M, the preset lower limit ratio be α, and the preset upper limit ratio be β. Then the preset working range of the data buffer is [αM, βM], where 0 < α < β < 1.

[0102] In this embodiment, α is 0.1 and β is 0.9. After the target audio stream endpoint enters continuous transmission state, if the real-time occupancy of the data buffer is lower than 0.1M or higher than 0.9M, or if an underload flag or an overflow flag is generated, it is determined that the data buffer state is not within the preset working range; otherwise, it is determined that the data buffer state is within the preset working range.

[0103] Audio format preservation status refers to whether the audio data maintains the data organization format corresponding to the current candidate capability during transmission. For native DSD, the detection host checks whether the data submitted to the endpoint maintains the native DSD data arrangement and confirms this in conjunction with the current audio format status returned by the device. For DoP, the detection host checks whether the format markers 0x05 and 0xFA alternate according to adjacent audio frames and checks whether the two channels use the same format marker in the same audio frame.

[0104] The audio format retention status indicates that the test audio data retains the data organization format corresponding to the current candidate capability in the USB data path. Without obtaining device-side format status, feedback endpoint data, or actual audio output confirmation information, the verified capability determined based on the aforementioned verification status data represents the verified data path transmission capability of the USB audio device under test under the current host, interface, and transmission configuration conditions. It does not directly indicate that the device has completed the decoding or audio processing of the corresponding audio format internally.

[0105] When the audio stream interface is configured, the target audio stream endpoint enters the transmission state, the test audio data is continuously transmitted, the effective transmission data volume reaches the data requirement of the current candidate capability during the verification period, and the audio format remains consistent, the current candidate capability is determined to meet the verification conditions.

[0106] Step S206: The detection host adjusts the test transmission strategy based on the verification status data generated during the initial verification of DSD256.

[0107] If the audio stream interface is not selected as a target alternative setting, the detection host selects another alternative setting capable of handling DSD256 data volume and re-executes the interface configuration. If the target audio stream endpoint is not started or stops during transmission, the detection host terminates the current transmission task, reinitializes the target audio stream endpoint, and resubmits the test audio data.

[0108] When data transmission is interrupted or the data buffer becomes underloaded, the detection host adjusts the data submission rhythm and data buffer capacity. Taking DoP DSD256 as an example, the buffer capacity for 10 milliseconds is: 5644800 × 10 ÷ 1000 = 56448 bytes.

[0109] After adjusting the buffer duration to 20 milliseconds, the buffer capacity is: 5644800×20÷1000=112896 bytes.

[0110] The testing host first writes 112,896 bytes of test audio data, and then starts endpoint transmission, so that the data writing end has the corresponding data reserve during the continuous reading of the endpoint.

[0111] When the native DSD data does not maintain the corresponding format, the detection host switches the audio stream interface to the alternative setting corresponding to DoP, sets the format marker alternately according to 0x05 and 0xFA, and keeps DSD256 as the current candidate capability for re-verification.

[0112] In this embodiment, when the DSD256 uses native DSD transmission, the current audio format status returned by the device is inconsistent with that of native DSD. The detection host switches to DoP transmission mode and re-verifies. During the re-verification, the target audio stream endpoint experiences a transmission interruption. The detection host reinitializes the target audio stream endpoint and adjusts the buffer capacity to 112896 bytes. After adjustment, the DSD256 still fails to generate verification status data that satisfies all verification conditions within the two-second verification period; therefore, it is determined that the DSD256 has failed the transmission verification.

[0113] In step S207, the detection host identifies DSD128 in the candidate capability sequence as the new current candidate capability.

[0114] The data requirement for a four-byte sub-slot dual-channel DoP DSD128 is 2,822,400 bytes / second. The data requirement for a two-second verification period is 2,822,400 × 2 = 5,644,800 bytes.

[0115] The PCM frame rate corresponding to DoP DSD128 is 352,800 frames / second, and the average number of frames per endpoint service interval is: 352,800 ÷ 8,000 = 44.1 frames.

[0116] Every ten service intervals require the transmission of 441 frames. The detection host submits 44 frames (352 bytes) in each of nine service intervals and 45 frames (360 bytes) in one service interval. The total data volume for ten service intervals is: 352 × 9 + 360 = 3528 bytes.

[0117] The testing host completes the two-second verification according to the above data submission rhythm. The audio stream interface enters the target candidate setting, the target audio stream endpoint works normally, the test audio data is continuously transmitted, the effective data transmission volume reaches 5,644,800 bytes, and the DoP format markers remain alternately arranged. Therefore, it is determined that DSD128 meets the verification conditions.

[0118] Since the candidate capability sequence is arranged from high to low according to data requirements, DSD128 is the first capability level that meets the verification conditions, and the detection host identifies DSD128 as the verification capability. If DSD128 still does not meet the verification conditions, then DSD64 is verified; if DSD64 also does not meet the verification conditions, the audio capability record is corrected to show that DSD transmission capability has not been verified.

[0119] In this embodiment, the target audio format is recorded as DSD, the verification capability is recorded as DSD128, and the DoP transmission method used during verification is written into the audio capability record corresponding to the USB audio device under test.

[0120] In step S208, the detection host determines the equalization processing verification items based on the corrected audio capability record, and obtains the input audio data and output audio data within the same audio processing time period according to the verified sampling configuration.

[0121] Input audio data refers to the audio data before entering the equalization processing unit, and output audio data refers to the audio data after being processed by the equalization processing unit. Equalization processing parameters refer to the gain, center frequency, and bandwidth parameters corresponding to each frequency range. In this embodiment, the equalization processing parameters are: increase the gain by 6 dB in the low-frequency range, maintain 0 dB in the mid-frequency range, and decrease the gain by 3 dB in the high-frequency range.

[0122] The detection host collects one second of input audio data and one second of output audio data at a sampling frequency of 96,000 Hz, with each set of data containing 96,000 sampling points. The detection host determines the processing delay based on the correlation between the input and output audio data, and aligns the two sets of data in time according to the sampling point offset corresponding to the maximum correlation, so that they correspond to the same audio processing period.

[0123] The input frequency domain characteristics and output frequency domain characteristics represent the energy or amplitude of the input and output audio data in each frequency range, respectively. This embodiment uses a 4096-point Fast Fourier Transform, with 2048 sampling points overlapping between adjacent analysis segments. The frequency corresponding to the Nth frequency point is calculated according to the following formula: Frequency = N × 96000 ÷ 4096.

[0124] The detection host calculates the input and output spectra for each analysis segment, and then averages the power of frequency points belonging to the same frequency range. Suppose there are N frequency points in a certain frequency range, and the average power is P. Then the frequency domain characteristics of this frequency range are calculated according to 10lg(P+ε), where ε is taken as 10^-12 to handle the case where the power is zero.

[0125] In this embodiment, 20 Hz to 200 Hz is defined as the low-frequency range, 200 Hz to 2000 Hz as the mid-frequency range, and 2000 Hz to 20000 Hz as the high-frequency range. The output frequency domain characteristics are subtracted from the input frequency domain characteristics for each frequency range to form the spectral change distribution before and after equalization processing.

[0126] For example, if the input frequency domain characteristics of the three frequency ranges are -20 dB, -18 dB, and -22 dB, and the output frequency domain characteristics are -14.3 dB, -17.8 dB, and -24.7 dB, respectively, then the spectrum variation distribution is as follows: Low frequency range: -14.3 - (-20) = 5.7 dB; Mid frequency range: -17.8 - (-18) = 0.2 dB; High frequency range: -24.7 - (-22) = -2.7 dB.

[0127] The preset spectral variation characteristics refer to the target gain for each frequency range predetermined based on the equalization processing parameters. In this embodiment, these are 6 dB, 0 dB, and -3 dB. Subtracting the actual spectral variation from the corresponding target gain and taking the absolute value yields deviations of 0.3 dB, 0.2 dB, and 0.3 dB for the three frequency ranges, respectively. The preset allowable deviation is 1 dB. Since all three deviations are within the allowable range, the equalization processing result is determined to meet the preset processing requirements.

[0128] Step S209: The testing host determines the device function test items based on the calibrated audio capability record.

[0129] When the calibrated audio capability record includes an audio input channel, microphone input detection is initiated. Microphone input data refers to the sampled data uploaded by the USB audio device under test to the testing host via the audio input channel. Microphone input status refers to whether the audio input channel can generate continuous amplitude changes corresponding to external sounds.

[0130] In this embodiment, microphone input data was continuously acquired for two seconds at a sampling frequency of 48,000 Hz, resulting in a total of 96,000 sampling points. The detection host divides the data into an analysis frame every 20 milliseconds, and each frame contains: 48,000 × 20 ÷ 1000 = 960 sampling points.

[0131] Let the normalized sample values ​​within a frame be s1 to s960. The root mean square amplitude of this frame is calculated by taking the square root of the sum of the squares of each sample value divided by 960, and then converted to a decibel value using 20lg(root mean square amplitude + ε). The detection host uses the average amplitude of the first 0.5 seconds as the environmental reference amplitude, and subtracts the average amplitude of the subsequent test sound period from the environmental reference amplitude. In this embodiment, the environmental reference amplitude is -52 dB, and the average amplitude of the test sound period is -24 dB, with an amplitude increment of 28 dB, meeting the preset 10 dB change requirement. Therefore, the microphone input status is determined to be normal.

[0132] The testing host determines the channel output testing items based on the number of output channels in the calibrated audio capability record. Channel test data refers to audio data where the test signal is set in only one target channel, and the remaining channels are muted. Test confirmation information refers to information obtained from the audio acquisition component, equipment status information, or the testing confirmation terminal, which indicates the actual output channels of the test signal.

[0133] For dual-channel devices, the testing host first sends a 1000 Hz test signal to the left channel and mutes the right channel. Then, it sends the same test signal to the right channel and mutes the left channel. The testing host calculates the root mean square amplitude of the target channel and the non-target channel respectively. When the amplitude of the target channel reaches the preset output range and is more than 30 dB higher than the amplitude of the non-target channel, the output status of the corresponding channel is determined to be normal.

[0134] When the USB audio device under test has interactive input functionality, the detection host receives button information reported by the device in response to physical button operations. This button information includes the button identifier, pressed state, released state, and reporting time. The detection host compares the actually reported button identifier and state changes with preset button events; if they match, the button response is considered normal.

[0135] Reference device parameters refer to the device identification parameters, audio interface parameters, and audio capability parameters obtained from standard USB audio devices with confirmed functionality. The testing host compares the supplier identification, product identification, number of interfaces, endpoint configuration, number of channels, and calibrated DSD capability data of the USB audio device under test with the reference device parameters item by item to form a device parameter comparison result.

[0136] The testing host generates device function test results based on at least one of the following: microphone input status, channel output status, button response status, and device parameter comparison results. It also writes the tested items, test data, and status of each item into the corresponding device's test record.

[0137] Example 3: The above detection method is performed by a detection system 100 based on a USB audio playback device, which includes a data acquisition module 110, a storage module 120, and a processing module 130.

[0138] The above detection method is performed by a detection system 100 based on a USB audio playback device, which includes a data acquisition module 110, a storage module 120, and a processing module 130.

[0139] The data acquisition module 110 includes a USB communication interface for connecting to the USB audio device under test, acquiring capability description data, transmission configuration data, channel configuration data, and verification status data of the USB audio device under test, and transmitting test audio data to the USB audio device under test.

[0140] Storage module 120 is used to store device data requirements for different capability levels, test audio data, test transmission strategies, audio capability records, and computer programs.

[0141] The processing module 130 runs the computer program in the storage module 120 to execute the above-described detection method for USB audio playback devices. The processing module 130 establishes a candidate capability sequence based on capability description data, transmission configuration data, and channel configuration data; controls the USB audio device under test to perform transmission verification; adjusts the test transmission strategy based on the verification status data; and determines the verification capability and corrected audio capability records based on the verification results.

[0142] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A detection method for a USB audio playback device, characterized in that, include: Obtain the capability description data, transmission configuration data, and channel configuration data of the USB audio device under test; When the capability description data lacks valid capability information for the target audio format, the theoretical transmission capability is determined by the transmission configuration data, the device data requirements are determined according to the capability levels of the target audio format and the channel configuration data, the two are compared and a candidate capability sequence is established. Select the current candidate capability, generate a test transmission strategy, and control the USB audio device under test to transmit test audio data; Determine whether the current candidate capability has passed verification based on the verification status data; If the test fails, adjust the test transmission strategy based on the verification status data and re-verify the current candidate capability; if it still fails, verify the next candidate capability. The verification capability is determined based on the verification results, and the audio capability record of the USB audio device under test is corrected.

2. The detection method for a USB audio playback device according to claim 1, characterized in that, The target audio format is DSD audio format, the capability description data includes USB device descriptor, audio control interface description information and audio stream interface description information, and the effective capability information includes DSD transmission mode and DSD capability level; If the DSD transmission method is not obtained, the DSD capability level is not obtained, or the obtained DSD transmission method does not correspond to the DSD capability level, it is determined that the capability description data lacks the valid capability information.

3. The detection method for a USB audio playback device according to claim 2, characterized in that, The USB bus speed is full speed or high speed, the transmission configuration data includes the maximum packet information of the audio stream endpoint, the endpoint polling interval and the USB bus speed, and the channel configuration data includes the number of audio channels; The data carrying capacity of the audio stream endpoint in a single transmission cycle is determined based on the endpoint maximum packet information. The data transmission frequency per unit time is determined based on the endpoint polling interval and the USB bus speed. The theoretical data transmission volume is determined based on the data carrying capacity and the data transmission frequency, and the theoretical data transmission volume is used as the theoretical transmission capacity.

4. The detection method for a USB audio playback device according to claim 3, characterized in that, Based on the effective data requirements of each channel of different DSD capability levels, the number of audio channels, and the encapsulation overhead corresponding to the available audio data encapsulation methods, the device data requirements of each DSD capability level under each available audio data encapsulation method are determined respectively. DSD capability levels with at least one device data requirement not exceeding the theoretical data transmission volume are added to the candidate capability sequence and arranged from high to low according to the DSD capability level. The DSD capability level at the top of the candidate capability sequence is determined as the current candidate capability for the first verification.

5. The detection method for a USB audio playback device according to claim 4, characterized in that, The test transmission strategy includes the audio stream interface corresponding to the current candidate capability, interface alternative settings, target audio stream endpoint, audio data encapsulation method, data submission rhythm, data buffer capacity, and preset verification duration. The verification status data includes interface configuration status, endpoint startup status, data transmission continuity status, effective data transmission volume, data cache status, and audio format preservation status. When the audio stream interface is configured, the target audio stream endpoint enters the transmission state, the test audio data is continuously transmitted within the preset verification duration, the effective transmission data volume is not less than the product of the device data requirement of the current candidate capability under the currently adopted audio data encapsulation method and the preset verification duration, the data cache state is within the preset working range, and the test audio data maintains the corresponding audio format, it is determined that the current candidate capability meets the verification conditions.

6. The detection method for a USB audio playback device according to claim 5, characterized in that, Adjusting the test transmission strategy based on the verification status data includes: When the interface configuration status is abnormal, switch the alternative interface settings for the audio stream interface and reconfigure the audio stream interface; If the endpoint startup state is abnormal, the target audio stream endpoint will be reinitialized. When the data transmission continuity is abnormal or the data buffer state is not within the preset working range, adjust the data submission rhythm and / or the data buffer capacity. When the audio format preservation state is abnormal, the audio data encapsulation method is switched; The current candidate capability is maintained according to the adjusted test transmission strategy, and transmission verification is performed again.

7. The detection method for a USB audio playback device according to claim 6, characterized in that, If the current candidate capability still does not meet the verification conditions after the test transmission strategy is adjusted, the next DSD capability level in the candidate capability sequence is determined as the new current candidate capability, and transmission verification is performed in descending order of the candidate capability sequence. The first DSD capability level that meets the verification conditions is determined as the verified capability. If none of the DSD capability levels meet the verification conditions, the audio capability record is corrected to show that the DSD transmission capability has not been verified.

8. The detection method for a USB audio playback device according to claim 1, characterized in that, Based on the corrected audio capability record, determine the equalization processing verification items, obtain the input audio data before equalization processing and the output audio data after equalization processing within the same audio processing time period, extract the frequency domain features of the input audio data and the output audio data in multiple frequency ranges respectively, form the spectral change distribution before and after equalization processing, and compare the spectral change distribution with the preset spectral change features corresponding to the equalization processing parameters to determine the equalization processing result.

9. The detection method for a USB audio playback device according to claim 1, characterized in that, The device function testing items are determined based on the corrected audio capability records. These items include: When the audio capability record includes an audio input channel, the microphone input status is determined based on the microphone input data corresponding to the audio input channel. The channel output detection items are determined based on the number of output channels in the audio capability record, channel test data is transmitted to different audio output channels respectively, and the channel output status is determined based on the test confirmation information. When the USB audio device under test has interactive input function, the button response state is determined based on the button information reported by the USB audio device under test in response to physical button operation. The device parameters of the USB audio device under test are compared with the reference device parameters of a standard USB audio device to form a device parameter comparison result. The device function test result is generated based on the microphone input status, the channel output status, the button response status, and the device parameter comparison result.

10. A detection system based on a USB audio playback device, characterized in that, It includes a data acquisition module, a storage module, and a processing module; The data acquisition module includes a USB communication interface for connecting to the USB audio device under test, acquiring the capability description data, transmission configuration data, channel configuration data and verification status data of the USB audio device under test, and transmitting test audio data to the USB audio device under test. The storage module is used to store device data requirements, test audio data, audio capability records, and computer programs at different capability levels. The processing module is used to run the computer program to perform the detection method for a USB sound playback device according to any one of claims 1 to 9.

Images