Method for adjusting the sound characteristics during the playback of successive audio tracks and audio playback device

Abstract

Method for adjusting the sound characteristics during the playback of successive audio pieces, wherein the playback is carried out according to a first operating mode or a second operating mode and wherein, - at the beginning of a new audio piece, a genre of the audio piece is determined (11) by evaluating the additional data available in the first operating mode which specifies the genre of the respective audio piece and by analyzing the audio signal in the second operating mode to determine the genre of the respective audio piece; - a sound characteristic is selected depending on the specific genre (12); - the frequency response of the audio signal is automatically adjusted for playback depending on the selected sound characteristic (13); and - in the second operating mode, the end of the audio piece is additionally determined in order to then determine the genre of a subsequent audio piece at the beginning of that subsequent audio piece.

Description

[0001] The present invention relates to a method for adjusting the sound characteristics during the playback of successive audio tracks. The invention further relates to an audio playback device in which such a method according to the invention is used.

[0002] Audio playback devices often allow the sound characteristics to be influenced by varying the amplification or attenuation of different frequency ranges of the input signal. For this purpose, the input signal can be divided into a multitude of frequency bands using suitable filters, but often it is simply divided into high, mid, and low frequencies.

[0003] Depending on the implementation, the frequency ranges can be adjusted manually and independently, or they can be set by selecting presets such as "Dynamic," "Neutral," or "Acoustic," which have predefined frequency responses. Such adjustment of the sound characteristics during audio playback is also typically possible with car radios or infotainment systems installed in vehicles. In this case, automatic adjustment is desirable so that the driver is not unnecessarily distracted by manual input and can instead focus their attention on driving.

[0004] For example, DE 198 48 491 A1 describes a method for influencing the sound characteristics of an audio signal to be played back in a radio receiver, in particular an RDS car radio. In this method, a frequency response is assigned to each of the various program type identifiers in a memory, which is considered ideal for playing back an audio signal identified by the assigned program type identifier. For the playback of a received audio signal, the assigned sound characteristic is assigned to an equalizer depending on the currently received program type identifier, thus enabling automatic adjustment of the sound characteristics to the program type of the received program.The program type identifier corresponds in particular to the additional information PTY (program type) specified in the RDS standard, which indicates a classification of analog FM radio stations according to genres such as pop music, news, classical music or jazz.

[0005] Similarly, DE 198 54 125 A1 discloses a playback device for audio signals stored on audio signal carriers, in particular a car radio with an attached CD changer, in which various audio signal carrier identifiers and sound characteristics assigned to the audio signal carriers or the stored identifiers are stored in a memory. The sound characteristics of an audio signal to be played back are influenced by an equalizer depending on the sound characteristics assigned in the memory, so that when an audio signal carrier is selected, it is automatically played back with a sound characteristic optimally adapted to the user's listening habits.

[0006] Similarly, WO 2004 / 114718 A1 proposes processing an audio signal in a car radio before playback according to a predefined sound spectrum, whereby the appropriate sound spectrum is determined from a multitude of different sound spectra by means of a sound selection device. The sound selection device automatically selects the sound spectrum after a change in the input signal, for example, by selecting a different data signal source or a different radio program, depending on additional information assigned to the audio signal. For this purpose, various sound spectra are assigned to the additional information in a memory, whereby the additional information can include, in particular, a program type identifier, station identifier, text information, or information about the type of signal source from which the audio signal is output. The additional information can also be obtained by frequency and / or dynamic analysis of the audio signal.

[0007] Furthermore, DE 10 2015 005 007 A1 discloses a method for improving the sound quality of an audio file, in which metadata is evaluated and a default setting is activated if no metadata is present. DE 10 2015 008 070 A1 describes a method for adjusting the sound of an audio signal, in which the audio signal is automatically analyzed with regard to its audio content, such as music and / or speech, and a sound adjustment and / or improvement is automatically performed depending on this music analysis. Finally, US 2010 / 0 286 806 A1 discloses a method for data analysis for an audio player, which includes analyzing at least a portion of the audio data, selecting a sound profile based on the analysis of the audio data, adjusting the sound field settings according to the sound profile, and outputting at least a portion of the audio data according to the sound field settings.

[0008] It is an object of the present invention to provide an improved method for automatically adjusting the sound characteristics during audio playback, which can be used particularly in a motor vehicle.

[0009] This problem is solved by a method having the features of claim 1. Preferred embodiments of the invention are the subject of the dependent claims.

[0010] In the inventive method for adapting the sound characteristics during the playback of successive audio pieces, the playback takes place according to a first operating mode or a second operating mode, wherein - at the beginning of a new audio piece, a genre of the audio piece is determined by evaluating additional data present in the first operating mode, which specifies the genre of the respective audio piece, and by analyzing the audio signal in the second operating mode to determine the genre of the respective audio piece; - a sound characteristic is selected depending on the specific genre; - the frequency response of the audio signal is automatically adjusted for playback depending on the selected sound characteristic; and - in the second operating mode, the end of the audio piece is additionally determined in order to then determine the genre of a subsequent audio piece at the beginning of that subsequent audio piece.

[0011] Unlike the aforementioned state of the art, this method optimizes the sound characteristics not only when the program type changes due to a station change, CD change, or signal source change. Rather, optimization also occurs when no such change takes place, but the genre or musical style of successive audio tracks nevertheless changes frequently. Because the second operating mode analyzes the audio signal to determine the genre of the audio track, automatic adjustment of the sound characteristics is possible even for audio tracks for which no genre information is available. In this way, the individual audio tracks can be optimized for playback, in particular... - received via analog or digital radio transmission; - as digital audio files read from a local storage device or loaded from an external storage device; or - as digital audio data streamed from an external storage device.

[0012] Advantageously, in the first operating mode, the additional data is included in the audio track.

[0013] The audio track can be in MP3 format, with additional data contained in an ID3 tag. Depending on the genre specified in the ID3 tag, one of several sound characteristics is selected. Since the MP3 format is widely used for digital audio data, this method allows for automatic adjustment of the sound characteristics to a large number of audio tracks.

[0014] It is also advantageous to send the audio signal to an external computer system for analysis. This external system can then analyze the transmitted audio signal to determine the genre of the audio piece and receive additional data specifying the genre. This allows for the rapid execution of even computationally intensive analyses. Furthermore, it enables the highly reliable identification of an audio piece, allowing access, if necessary, to databases containing additional data for that identified audio piece.

[0015] The adjustment of the sound characteristics and the playback of audio tracks can be particularly advantageous in a vehicle.

[0016] An audio playback device according to the invention is configured to carry out a method for adjusting the sound characteristics during the playback of successive audio pieces according to one of the preceding claims.

[0017] Further features of the present invention will become apparent from the following description and the claims in conjunction with the figures. Fig. Figure 1 schematically shows a flowchart for a method according to the invention for adjusting the sound characteristics; Fig. Figure 2 schematically shows a flowchart for a method according to the invention with two different operating modes.

[0018] To better understand the principles of the present invention, embodiments of the invention are explained in more detail below with reference to the figures. It is understood that the invention is not limited to these embodiments and that the described features can also be combined or modified without departing from the scope of protection of the invention as defined in the claims.

[0019] Fig. Figure 1 schematically illustrates a method for adjusting the sound characteristics, which is performed for each successive audio track during playback. The audio tracks can be any time-limited audio contributions, such as musical pieces or spoken word recordings.

[0020] In the first step (10), the audio track is received by an audio playback device or a computer program for playing audio data. The audio track can be in the form of digital audio data, which may be stored on a local storage device, such as a hard drive or flash memory, and read from it for playback. Alternatively, the digital audio data can be downloaded as an audio file from an external storage device or an online service, or continuously received and played back from a music streaming service. Furthermore, the digital audio data can also be received by a digital radio, such as a DAB or DAB+ receiver.Typically, digital audio data is encoded according to an audio compression standard, such as MP3 or AAC, and must first be decoded before further processing. This process can also separate additional data or metadata contained within the digital audio data.

[0021] For example, an MP3 file can contain additional information in so-called ID3 tags. This additional information can include the genre of the audio track, as well as other metadata such as the title, the name of the artist or performer, the album name on which the audio track is included, the year of release, or a comment. Depending on the version of the ID3 tags used, the additional information can be located in a block before or after the actual audio data in the MP3 file.

[0022] The genre of the current audio track is then determined in a second step, for example, by extracting the corresponding additional information from the ID3 tag of an MP3 file. The genre of the track is initially encoded as a numerical value. A list then indicates which value corresponds to which genre. This list was already relatively detailed in the first version of ID3 tags, with 80 different genre definitions, and was later expanded to include even more genres.

[0023] In the subsequent third step (12), the sound characteristics of the current audio track are selected based on its identified genre. For this, the audio playback device or computer program can, for example, access another list or table in which different frequency responses are assigned to the various styles of audio tracks, for instance, for setting an equalizer.

[0024] The adjustment of the audio track's frequency response then takes place in a fourth step, specifically using an equalizer composed of several filters that can manipulate the frequency spectrum of the input signal. The equalizer is integrated into the audio playback device or software, or interacts with it, and can access frequency responses tailored to different genres, allowing it to be adjusted according to the style of the audio being played. For example, a neutral frequency response can be selected for classical music, a dynamic frequency response with boosted bass for rock music, and boosted treble for speech. For this purpose, the audio signal can be divided into a multitude of frequency bands, each of which can be adjusted independently.

[0025] Frequency responses can be predefined for different genres or entered by the user. It is also possible for users to customize predefined frequency responses to their personal preferences. Furthermore, the frequency responses, especially in combination with the respective genre, can be stored locally from the outset or received from an online service, either along with an audio track or separately.

[0026] It is also conceivable that an audio track is assigned to more than one genre. In this case, one of the frequency response curves assigned to each genre can be selected, or a new frequency response curve can be generated. Similarly, it is possible that while no metadata exists for the genre of the current audio track, there is metadata for other information associated with the track, such as the artist's name. Since artists often rarely or never change their style, this additional information can then be used to predict and apply the genre of the current audio track.

[0027] However, even if no additional information is available for the current audio piece, for example because some of the audio pieces do not contain such additional information or radio operation takes place according to a transmission standard in which no additional information is transmitted, an automatic equalizer setting can be implemented.

[0028] For this purpose, the current audio track is analyzed at the start of playback. This can be done locally by the audio playback device or computer program, or online using specially designed software applications. By comparing the audio signal, or even watermarks embedded in the audio signal, with corresponding data in an online database, the currently playing audio track, and thus its genre, can be identified and used to select the appropriate frequency response.

[0029] However, even if the current audio track cannot be identified, a rough automatic equalizer setting is still possible. This is done in connection with Fig. Section 2 further clarifies this. In step 20, a distinction is first made between whether a radio playback mode or a different MP3 playback mode is currently active. In the example shown, no additional data specifying the genre of the audio track is present during radio playback, whereas this data may be present during MP3 playback. These two modes are purely illustrative; other modes, or even more than two modes, can also be distinguished.

[0030] To enable at least a rough frequency adjustment for the received radio signal despite the lack of additional data, the frequency pattern of the current audio track is analyzed in step 21. In step 22, a distinction is then made between whether the current audio track is a speech or music track. Based on this, an equalizer can be switched between the two playback types as needed. Thus, when a music track is detected in step 23, the playback can be adjusted accordingly, and when a speech track is detected in step 24, the playback can be adjusted accordingly. For example, when listening to a music station that primarily plays rock music, the user experience can be optimized by, on the one hand, strong bass during music playback and, on the other hand, boosted treble for better intelligibility during speech segments, such as news or traffic reports.

[0031] In the second operating mode, the example shown involves playing back MP3 audio files. As described above, these files can contain metadata in the form of ID3 tags. In step 25, the system checks whether an ID3 tag containing information about the genre of the current audio track is present. If so, the genre of the current audio track is read in step 26. Using this genre, the optimal equalizer setting for that genre is determined in step 27, and the audio signal is adjusted accordingly in step 28. If, however, the check in step 25 reveals that no ID3 tag is present or that it does not contain any genre information, a preset equalizer setting is selected that is generally well-suited for playing music from various genres.

[0032] According to the invention, genre determination is performed regularly, particularly at the beginning of each new audio track, in order to optimally adapt the frequency response for each played audio track. The end of one audio track and the beginning of the next can be calculated during playback of the current audio track if information about the track's length is available. This information can be transmitted along with the audio data of the current audio track. For example, an ID3 tag containing the audio file's length, such as in milliseconds, can be provided. Alternatively, the length of an audio track can be retrieved from a database if the audio track has been uniquely identified. If such information is unavailable, the transition from one audio track to the next can be achieved by analyzing the amplitude response.If the audio signal exhibits only a very low amplitude for a certain period of time, it can be assumed with a high degree of probability that this is a transition from one audio piece to the next.

[0033] Ideally, the audio track following the current one is already known in advance via a playlist, which defines a specific playback order for a compilation of digital music tracks. This makes it possible to determine the genre of the following audio track before it begins and to adjust its frequency response accordingly immediately upon its commencement.

[0034] The method according to the invention can be particularly advantageously used for audio playback in a motor vehicle and in particular can be integrated into an infotainment system that has a local media database, a radio receiver unit and / or a communication unit for a wireless connection to an online server.

[0035] The procedure can also be carried out partially or completely on a mobile device that is coupled to the vehicle's infotainment system, with audio playback via the vehicle's speakers, but the audio data originating from an internal memory of the mobile device.

[0036] Furthermore, the method according to the invention can also be used independently of a coupling with a motor vehicle for audio playback from mobile devices or other user terminal devices such as tablets, portable computer systems or stereo systems, etc. Reference symbol list 10 Receiving an audio piece 11 Determining the genre of the currently received audio track 12. Selection of sound characteristics based on genre 13. Adjusting the frequency response of the current audio track 20 Query of the operating mode 21 Analysis of the frequency response of the currently received audio track 22 Genre query 23, 29 Adjustment of the frequency response according to the preset “Music” 24 Adjusting the frequency response according to the "Language" preset 25 Query genre in ID3 tag 26 Select Genre 27 Determining the equalizer setting for the selected genre 28 Adjusting the frequency response according to genre

Claims

[1] Method for adjusting the sound characteristics during the playback of successive audio pieces, wherein the playback is carried out according to a first operating mode or a second operating mode and wherein, - at the beginning of a new audio piece, a genre of the audio piece is determined (11) by evaluating the additional data available in the first operating mode which specifies the genre of the respective audio piece and by analyzing the audio signal in the second operating mode to determine the genre of the respective audio piece; - a sound characteristic is selected depending on the specific genre (12); - the frequency response of the audio signal is automatically adjusted for playback depending on the selected sound characteristic (13); and - in the second operating mode, the end of the audio piece is additionally determined in order to then determine the genre of a subsequent audio piece at the beginning of that subsequent audio piece. [2] Method according to claim 1, wherein the individual audio pieces are selected for playback - received via analog or digital radio transmission (10); - as digital audio files read from a local storage device or loaded from an external storage device; or - as digital audio data streamed from an external storage device. [3] Method according to claim 1 or 2, wherein in the first operating mode the additional data is contained in the audio piece. [4] Method according to claim 3, wherein the audio piece is in MP3 format and the additional data is contained in an ID3 tag and one of several sound characteristics is selected depending on a genre specified in the ID3 tag. [5] Method according to one of the preceding claims, wherein the audio signal is sent to an external computer system for analysis, the transmitted audio signal is analyzed by the external computer system to determine the genre of the audio piece, and additional data specifying the determined genre is received from the external computer system. [6] Method according to one of the preceding claims, wherein the adjustment of the sound characteristics and the playback of the audio pieces takes place in a vehicle. [7] Audio playback device, configured to carry out a method for adjusting the sound characteristics when playing back successive audio pieces according to one of the preceding claims.

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