IP multicast wireless transmission system and encapsulation device

Abstract

It enables IP multicast from a transmitting device to a receiving device via wireless communication, providing stable transmission quality. [Solution] The IP multicast wireless transmission system transmits IP multicast packets from a transmitting device to one or more receiving devices via unidirectional communication. The transmitting device and receiving device are equipped with wireless communication units using a WHDI transmission method or WirelessHD transmission method for transmitting and receiving video signals using radio waves. The system includes a first control device that encapsulates IP multicast packets into a video signal format that can be transmitted using the WHDI transmission method or WirelessHD transmission method and outputs it to the transmitting device, and a second control device that extracts IP multicast packets from the video signals output from the receiving device. Data transmission is performed using an FEC method in which errors occurring in the transmission path between the transmitting device and the receiving device are corrected on the receiving device side.

Description

Technical Field

[0001] The present invention relates to wireless transmission technology for IP multicast packets.

Background Art

[0002] For example, IP multicast packets provided by an IP multicast broadcaster are sent through an IP network to a line termination device (such as an ONU, home gateway (HGW), CATV modem, ADSL modem, CTU, etc.) on the viewer side. There is an application form in which the line termination device transmits the IP multicast packet to a set-top box (STB), and the STB displays an image on a display such as a liquid crystal display device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] For example, in order to view video provided by an IP multicast broadcaster, it is necessary to connect and configure equipment such as a line termination device and a set-top box (STB) using HDMI cables or LAN cables. While IP broadcasting has mainly relied on wired communication-based connection environments, in recent years efforts have been made to build wireless communication-based connection environments. As described in Non-Patent Literature 1, attempts are being made to create a one-to-many wireless communication environment between the line termination device and the STB, which allows viewers to view IP broadcasts on multiple display devices.

[0006] However, when transmitting IP multicast packets wirelessly from a transmitting device to a receiving device, Wi-Fi® standard wireless communication cannot maintain the required transmission quality, posing a challenge in IP multicast communication of video signals (for example, Patent Document 1).

[0007] Various approaches have been taken to address this challenge. For example, attempts have been made to maintain transmission quality by improving FEC error correction technology while using Wi-Fi wireless communication standards, or by converting multicast packets to unicast packets for transmission within Wi-Fi wireless communication standards. There have also been attempts to use multiple bidirectional transmission paths and employ ARQ (Automatic Repeat reQuest) error correction technology to achieve high quality. However, these technical approaches have not provided a fundamental solution.

[0008] Wi-Fi-based one-to-one or one-to-many communication (IP-based wireless communication) is capable of low transmission rates and short distances, but high transmission rates and medium distances are difficult, and it cannot provide stable transmission quality. Furthermore, when converting multicast packets to unicast packets for transmission in Wi-Fi, ARQ error correction is used, making the use of a bidirectional transmission path essential. Regardless of whether it is Wi-Fi wireless communication or not, when employing ARQ error correction methods, it cannot be applied to the transmission of data in unidirectional communication.

[0009] The present invention aims to provide an IP multicast wireless transmission system that enables IP multicast from a transmitting device to a receiving device via wireless communication with stable transmission quality. [Means for solving the problem]

[0010] (1) The present invention is an IP multicast wireless transmission system that transmits IP multicast packets from a transmitting device to one or more receiving devices by unidirectional communication, wherein the transmitting device and the receiving device are equipped with wireless communication units that use a WHDI transmission method or a WirelessHD transmission method to send and receive video signals using radio waves.

[0011] The IP multicast wireless transmission system comprises a first control device that encapsulates IP multicast packets into a video signal format that can be transmitted using the WHDI transmission method or the WirelessHD transmission method and outputs it to a transmitting device, and a second control device that extracts IP multicast packets from the video signal output from a receiving device. The system can also be configured to transmit data using an FEC method, in which errors occurring in the transmission path between the transmitting device and the receiving device are corrected on the receiving device side.

[0012] (2) In (1) above, the first control device includes the following configuration: An external encoding unit divides an IP multicast packet into predetermined fixed-length byte data, generates multiple fixed-length data, applies external encoding processing to each of these data to generate external code parity bits, and concatenates the fixed-length data with the external code parity bits corresponding to the fixed-length data to generate externally encoded data. An interleaving unit performs interleaving, which rearranges each of the externally encoded data packets, which are arranged in the transmission order of the IP multicast packets, in a direction orthogonal to the scan lines of the video signal frame, and assigns the externally encoded data as pixels of the video signal. An internal encoding unit that extracts externally encoded data rearranged in a direction perpendicular to the scan lines in the direction of the scan lines, applies internal encoding processing to the extracted data to generate internal encoding parity bits, and adds the internal encoding parity bits to the extracted data to generate internally encoded data, and An output unit that converts internally encoded data into a video signal to be transmitted using the WHDI transmission method or WirelessHD transmission method and outputs it to the transmitting device.

[0013] (3) In (2) above, the first control device may further include a data control unit that divides an IP multicast packet into predetermined fixed-length byte data to generate a plurality of fixed-length data, and adds a synchronization pattern indicating the delimiter of an IP multicast packet to each fixed-length data. At this time, the external encoding unit can generate an external code parity bit by performing an external code encoding process on each fixed-length data to which the synchronization pattern has been added, and generate externally encoded data by concatenating the fixed-length data to which the synchronization pattern has been added with the external code parity bit corresponding to the fixed-length data to which the synchronization pattern has been added.

[0014] Furthermore, the first control device may include a backup unit that performs backup processing to swap the vertical and horizontal bit order of the internally encoded data, and the output unit may be configured to convert the data sequence after backup processing into a video signal that is transmitted using the WHDI transmission method or the WirelessHD transmission method and output it to the transmitting device.

[0015] (4) In (2) above, the second control device includes the following configuration: An internal code decoding unit performs error correction processing based on the internal code parity bit contained in the internal code data and generates data extracted in the scan line direction. A deinterleaving unit performs a deinterleaving process that rearranges the data extracted in the direction of the scan lines in a direction perpendicular to the scan lines, thereby generating externally encoded data arranged in the transmission order of IP multicast packets. An external code decoding unit performs error correction processing based on the external code parity bit contained in the external code encoded data after deinterleaving, and generates fixed-length data that constitutes an IP multicast packet. A concatenation unit for concatenating decoded fixed-length data, and A packet control unit that extracts IP multicast packets based on a concatenated set of fixed-length data.

[0016] (5) In (1) above, the first control device includes the following configuration: A data control unit divides an IP multicast packet into predetermined fixed-length byte data to generate multiple fixed-length data, divides each of these fixed-length data into multiple byte-length data, and assigns each of the divided byte-length data to a different partition area. An external encoding unit performs an external encoding process on each divided region to which byte-length data is allocated. This external encoding process generates an external code parity bit by applying external code encoding to byte-length data, and then concatenates the byte-length data with the external code parity bit corresponding to that byte-length data to generate externally encoded data. An interleaving unit performs interleaving, where, for each divided region, the externally encoded data, arranged in the transmission order of IP multicast packets, is rearranged in a direction orthogonal to the scan lines of the video signal frame, and the externally encoded data is assigned as pixels of the video signal. An internal encoding unit generates a data sequence by cutting out externally encoded data in the direction of the scan line, rearranged in a direction orthogonal to the scan line for each divided region, and applies internal encoding processing to the data sequence group formed by concatenating the data sequences corresponding to each of the multiple divided regions to generate internally encoded parity bits, and assigns the generated internally encoded parity bits to a divided region other than the divided region to which byte-length data is allocated, and An output unit that converts each data sequence and internal parity bit generated for each divided region into a video signal to be transmitted using the WHDI transmission method or WirelessHD transmission method and outputs it to the transmitting device.

[0017] (6) In the above (5), the data control unit divides the IP multicast packet into byte data of a predetermined fixed length to generate a plurality of fixed-length data, adds a synchronization pattern indicating the delimiter of the IP multicast packet to each fixed-length data, divides the fixed-length data with the synchronization pattern added into a plurality of byte-length data, and can be configured to allocate each of the divided byte-length data to different divided areas.

[0018] Further, the first control device can be configured to include a retreat unit that performs a retreat process for swapping the vertical and horizontal bit order of data on the data sequence of each divided area generated in the inner encoding unit and the inner encoding parity bits of another divided area, and the output unit can be configured to convert each data sequence and the inner encoding parity bits after the retreat process into a video signal transmitted by the WHDI transmission method or the WirelessHD transmission method and output it to the transmission device.

[0019] (7) In the above (5), the second control device includes the following configuration. An inner code decoding unit that performs error correction processing based on the inner code parity bits assigned to another divided area and generates a data sequence group in which data sequences corresponding to a plurality of each divided area are concatenated; An deinterleaving unit that assigns the inner code decoded data sequence to the corresponding divided area, and for each divided area, performs a deinterleaving process of rearranging the data sequence cut out in the scanning line direction in a direction orthogonal to the scanning line to generate outer encoded data arranged in the transmission order of the IP multicast packet; An outer code decoding unit that performs error correction processing based on the outer code parity bits included in the outer encoded data after deinterleaving for each divided area to generate byte-length data; A combining unit that integrates the corresponding byte-length data assigned to each divided area to generate fixed-length data; A connecting unit that concatenates the synthesized fixed-length data; and A packet control unit that extracts an IP multicast packet based on the concatenated fixed-length data group.

[0020] (8) The present invention relates to an encapsulation device that receives an IP multicast packet provided from a data source and encapsulates the IP multicast packet in a video signal format that can be transmitted using a WHDI transmission method or a WirelessHD transmission method.

[0021] The encapsulation device divides an IP multicast packet into predetermined fixed-length byte data, and for each of the multiple fixed-length data generated, it performs external code encoding to generate an external code parity bit, and then concatenates the fixed-length data with the external code parity bit corresponding to the fixed-length data to generate externally encoded data. An interleaving unit performs interleaving, which rearranges each of the externally encoded data packets, which are arranged in the transmission order of the IP multicast packets, in a direction orthogonal to the scan lines of the video signal frame, and assigns the externally encoded data as pixels of the video signal. An internal encoding unit that extracts externally encoded data rearranged in a direction perpendicular to the scan lines in the direction of the scan lines, applies internal encoding processing to the extracted data to generate internal encoding parity bits, and adds the internal encoding parity bits to the extracted data to generate internally encoded data, and It includes an output unit that converts internally encoded data into a video signal transmitted using the WHDI transmission method or the WirelessHD transmission method and outputs it. [Effects of the Invention]

[0022] According to the present invention, in IP multicast from a transmitting device to one or more receiving devices via unidirectional communication, the wireless communication between the transmitting device and the receiving device is configured using a WHDI transmission method or a WirelessHD transmission method that transmits and receives video signals using radio waves, and the IP multicast packets are encapsulated in the video signals before transmission. This enables high transmission rates and medium-distance transmission, and because data is transmitted using an FEC (Forward Error Correction) method, transmission errors can be corrected at the receiving end without retransmitting the data, and the data can be received without delay. Therefore, wireless communication from the transmitting device to one or more receiving devices can be performed with stable transmission quality. [Brief explanation of the drawing]

[0023] [Figure 1] This is a schematic diagram of the IP multicast wireless transmission system according to the first embodiment. [Figure 2] This is a functional block diagram of the first control device (transmitter side) of the first embodiment. [Figure 3] This figure illustrates various processes of the first control device (transmitter side) of the first embodiment, including fixed-length division, synchronization pattern addition, external coding, interleaving, and internal coding. [Figure 4] This diagram illustrates the bit interleaving process of the first control device (transmitter side) in the first embodiment. [Figure 5] This is a functional block diagram of the second control device (receiving side) of the first embodiment. [Figure 6] This is a functional block diagram of the first control device (receiving side) that encapsulates IP multicast packets in video signals corresponding to multiple data areas according to the first embodiment. [Figure 7] This diagram illustrates the various processes involved in encapsulating IP multicast packets in video signals corresponding to multiple data areas in the first embodiment. [Figure 8] This figure illustrates the internal encoding process when encapsulating an IP multicast packet in a video signal corresponding to multiple data areas in the first embodiment. [Figure 9] This is a functional block diagram of a second control device (receiving side) that supports encapsulating IP multicast packets in video signals corresponding to multiple data areas in the first embodiment. [Best Mode for Carrying Out the Invention]

[0024] The embodiments will be described below with reference to the drawings.

[0025] (First Embodiment) Figures 1 to 9 are diagrams illustrating the first embodiment. Figure 1 is a schematic diagram of the IP multicast wireless transmission system of this embodiment.

[0026] The IP multicast wireless transmission system of this embodiment realizes IP multicast by wireless communication from a transmitting device T to one or more receiving devices R via unidirectional communication. It comprises a first control device 10 to which IP multicast packets distributed from a sender (data source) such as a distribution carrier are input, a transmitting device T connected to the first control device 10, a plurality of receiving devices R paired with the transmitting device T, and a plurality of second control devices 20 (20A to 20C) connected to each receiving device R. Equipment D is connected to each second control device 20.

[0027] The following description will use a configuration in which a signal is transmitted from one transmitting device T to multiple receiving devices R via unidirectional communication as an example, but it is not limited to this configuration, and a configuration in which a signal is transmitted from one transmitting device T to one receiving device R is also possible. In other words, the IP multicast wireless transmission system of this embodiment can realize one-to-one or one-to-many IP multicast via wireless communication. Unidirectional communication (Simplex Communication) is a communication channel or communication method in which signals or data can only be sent in a specific one direction.

[0028] The transmitting device T and the receiving device R are equipped with wireless communication units Tt and Rt that transmit and receive video signals using WHDI transmission or WirelessHD transmission, and a non-IP wireless transmission path is formed between the transmitting device T and the receiving device R. Hereinafter, the WHDI transmission or WirelessHD transmission method will be referred to as the non-IP wireless transmission method.

[0029] The wireless communication unit Tt of the transmitting device T has a transmission function that sends video signals to the wireless communication unit Rt of the receiving device R using a non-IP wireless transmission method, and the wireless communication unit Rt of the receiving device R has a reception function that receives video signals sent from the transmitting device T.

[0030] Non-IP wireless transmission methods, such as the WirelessHD transmission method, can transmit uncompressed or compressed data to the receiving side using the HRP (High-rate physical layer) communication method. HRP is a unidirectional communication method and is suitable for transmitting large amounts of data. The wireless communication unit Tt of the transmitting device T performs communication compliant with the WirelessHD transmission method, for example, by establishing a communication channel using HRP and transmitting data through the communication channel. The same applies to the WHDI transmission method, where a communication channel is established using a predetermined communication method and uncompressed or compressed data is transmitted to the receiving side.

[0031] Furthermore, the communication methods for WHDI transmission or WirelessHD transmission can be appropriately adapted from known technologies. Also, WHDI transmission or WirelessHD transmission is a transmission method based on the premise of transmitting video signal streams (non-IP wireless communication) and cannot transmit IP packets.

[0032] IP multicast is a communication format that delivers the same data (IP packets) to multiple recipients (devices belonging to a specific group) in a single transmission. The sender can pre-manage a group of multiple users (destinations) to whom IP multicast packets will be distributed.

[0033] Use cases for IP multicast include, for example, content distribution (video streaming, live video streaming, etc.) and IP broadcasting. In content distribution and IP broadcasting, IP multicast packets containing video data are distributed. On the other hand, software (program) distribution can also be done using IP multicast. In this case, IP multicast packets containing programs and modules that make up the software are multicast. The IP multicast wireless transmission system of this embodiment can be applied to IP multicast containing not only video data but also any information depending on the IP multicast use case.

[0034] Non-IP wireless transmission methods can transmit radio waves conforming to video signal standards such as HDMI signals (HDMI is a registered trademark) and SDI signals (SD-SDI, MD-SDI). They encapsulate IP multicast packets using video signal standards that can be transmitted by non-IP wireless transmission methods (for example, embedding the byte sequence constituting the IP multicast packet into a Full HD (1920 x 1080 pixels) video frame), and wirelessly transmit the video signal with the IP multicast packets embedded as pixels from the transmitting device T to each of the multiple receiving devices R.

[0035] The IP multicast wireless transmission system of this embodiment is not particularly limited in terms of the type of information contained in the encapsulated IP multicast packets; it may be an IP multicast containing video data or an IP multicast packet containing information other than video data. Furthermore, the format of the video signal that can be transmitted by a non-IP wireless transmission system can be arbitrarily set.

[0036] In the case of content distribution or IP broadcasting, the device D connected to the second control device 20 is, for example, a device that connects to a display device such as a set-top box (STB) to display content such as videos. A computer device can also view videos and can be configured as device D. The same applies to software distribution; an STB, display device, or computer device that runs on an operating system, applications, and various programs can be configured as device D.

[0037] As mentioned above, the Wi-Fi® standard, a representative IP communication protocol, has the challenge of not being able to maintain the transmission quality of one-to-one or one-to-many IP multicast packets. Various approaches have been attempted to address this challenge, but high transmission rates and medium-distance transmission have been difficult, and stable transmission quality has not been provided.

[0038] As shown in Figure 1, the IP multicast wireless transmission system of this embodiment is configured such that communication between the transmitting device T and the receiving device R is performed using a non-IP wireless transmission method that transmits and receives video signals using radio waves, and the system includes a first control device 10 that encapsulates IP multicast packets in the format of video signals for the transmitting device T, and a second control device 20 that extracts IP multicast packets from the video signals input from the receiving device R.

[0039] In other words, the wireless transmission path from the transmitting device T to the receiving device R is not an IP-based wireless communication method such as Wi-Fi, but rather a non-IP-based wireless transmission path, and the video signal is encapsulated with IP multicast packets. The non-IP-based wireless transmission method enables high transmission rates and medium-distance transmission (e.g., 30m, 3Gbps), and in IP multicast, it can perform wireless transmission from one transmitting device T to one or more receiving devices R with stable transmission quality.

[0040] Furthermore, it employs FEC (Forward Error Correction), which corrects errors occurring in the non-IP wireless transmission path between the transmitter T and the receiver R on the receiver R side. This allows the receiver to correct transmission errors without retransmitting the data, ensuring that data is received without delay.

[0041] As described above, the IP multicast wireless transmission system of this embodiment includes wireless communication units Tt and Rt that transmit and receive video signals using WHDI transmission or WirelessHD transmission methods, with the transmitting device T and the receiving device R transmitting IP multicast packets from the transmitting device T to the receiving device R via unidirectional communication. The system also includes a first control device 10 that encapsulates the IP multicast packets into a video signal format that can be transmitted using the WHDI transmission or WirelessHD transmission method and outputs it to the transmitting device T, and a second control device 20 that extracts IP multicast packets from the video signal output from the receiving device R. Furthermore, the system is configured to transmit data using an FEC method in which errors occurring in the transmission path between the transmitting device T and the receiving device R are corrected on the receiving device R side.

[0042] In this embodiment, the configuration in which the first control device 10 and the transmitting device T are separate devices has been described as an example, but the first control device 10 and the transmitting device T may be configured as an integrated device. The same applies to the second control device 20 and the receiving device R; the second control device 20 and the receiving device R may be configured as an integrated device.

[0043] <Description of the first control device> Figure 2 is a functional block diagram of the first control device 10 of this embodiment. The input side of the first control device 10 is connected to the data source, and the output side is connected to the transmitting device T. IP multicast packets are input from the data source to the first control device 10. The transmission paths between the data source and the first control device 10, and between the first control device 10 and the transmitting device T, can be wired or wireless.

[0044] As shown in Figure 2, the first control device 10 is configured to include a data control unit 101, an external encoding unit 102, an interleaving unit 103, an internal encoding unit 104, a storage unit 105, and an output unit 106.

[0045] Figures 3 and 4 are diagrams illustrating the various processes of the first control device 10. The first control device 10 is an encapsulation device that generates a video signal in which IP multicast packets are encapsulated by executing processes in the following order: fixed-length division, synchronization pattern addition, external coding, interleaving, internal coding, and saving.

[0046] As shown in Figure 3, the data control unit 101 performs fixed-length segmentation processing and synchronization pattern addition processing. The input IP multicast packet is divided into predetermined fixed-length byte data to generate multiple fixed-length data. At this time, a synchronization pattern indicating the delimiter of the IP multicast packet is added to each fixed-length data. The remaining space after segmentation can be filled with NULL. The fixed length is arbitrary.

[0047] Next, the external encoding unit 102 performs external encoding processing. For each fixed-length data to which a synchronization pattern is attached, it performs external encoding processing to generate an external code parity bit, and then concatenates the fixed-length data to which the synchronization pattern is attached with the external code parity bit corresponding to that fixed-length data to which the synchronization pattern is attached to generate externally encoded data.

[0048] The interleaving unit 103 rearranges each of the externally encoded data, which are arranged in the transmission order of the IP multicast packets, in a direction orthogonal to the scan lines of a frame based on a predetermined video signal format that can be transmitted by a non-IP wireless transmission method, and performs interleaving by assigning the externally encoded data as pixels of the video signal.

[0049] The internal encoding unit 104 extracts the externally encoded data, which has been rearranged in a direction orthogonal to the scan lines, in the direction of the scan lines, and applies internal encoding processing to the extracted data to generate internal code parity bits. The generated internal code parity bits are added to the extracted data to generate internally encoded data.

[0050] The backup unit 105 performs a backup process that swaps the vertical and horizontal bit order of the internally encoded data along the data transmission direction (direction of wireless transmission). This backup process is bit interleaving. For example, as shown in Figure 4, the internally encoded data is associated with each pixel that makes up the frame of the video signal. If one pixel is, for example, one byte, then the information contained in one pixel is 8 bits. The 8-bit data sequence is arranged in order from the most significant bit (MSB) to the least significant bit (LSB).

[0051] The backup unit 105 performs bit interleaving on each pixel of the internally encoded data arranged in the data transmission direction. In the example in Figure 4, the vertical and horizontal orientations of a data sequence for one pixel (8 bits) are transposed. At this time, it is possible to set how many bits from the MSB are transposed in the 8-bit data sequence after vertical and horizontal transposition. For example, if the placement position N from the MBS is set to 5, in the example data for one pixel after transposition, the transposed bits of the internally encoded data will be placed up to the 5th position from the MBS, and the 6th to 8th positions can be filled with NULL or any numerical value. Although a data sequence of 8 bits per pixel has been explained as an example, for example, a data sequence of 24 bits per pixel may also be used, and the data capacity corresponding to one pixel can be set as appropriate.

[0052] The output unit 106 converts the data stream after the backup process into a video signal for a non-IP wireless communication method and outputs the video signal (video stream) in which the IP multicast packets are encapsulated to the transmitting device T.

[0053] As described above, since the wireless communication between the transmitting device T and each of the multiple receiving devices R is configured using a non-IP wireless transmission method and the IP multicast packets are encapsulated in a predetermined video signal format, even in one-to-many IP multicast, wireless communication from one transmitting device T to each of the multiple receiving devices R can be performed with stable transmission quality.

[0054] On the other hand, while WHDI and WirelessHD transmission methods tolerate a certain degree of data loss to prevent a significant degradation of the bit error rate (BER), data loss due to uncorrectable transmission errors affects transmission quality, so it is always better to minimize uncorrectable transmission errors.

[0055] Forward Error Correction (FEC) allows the receiver to correct transmission errors without retransmitting data and extract data without delay, but it still introduces a certain degree of bit error rate (BER). Therefore, minimizing the degradation of transmission quality due to data loss is a crucial aspect of wireless communication technology. For example, in IP multicast communication including video data, data loss can cause video distortion or interruptions, making the suppression of transmission quality degradation due to data loss even more important.

[0056] Therefore, as a mechanism to suppress the deterioration of transmission quality due to information loss, the first control device 10 of this embodiment is configured to perform interleaving between the external coding and internal coding processes to suppress information loss due to burst errors. In addition, the effects of discarding several bits of information on the LSB (least significant bit) side are avoided by the saving process.

[0057] In this embodiment, interleaving rearranges each of the externally encoded data, which are arranged in the transmission order of the IP multicast packets, in a direction orthogonal to the scan lines of the frame based on a predetermined video signal format that can be transmitted by a non-IP wireless transmission system, and assigns the externally encoded data as pixels of the video signal. Therefore, for example, even if an entire scan line is lost due to a burst error, only one byte of the externally encoded data, which is arranged in a direction orthogonal to the scan lines of the frame, will be lost, and it can be properly (effectively) decoded by error correction processing based on the external code parity bit. As will be described later, for example, in a 1920 x 1080 pixel video signal, with 120 bytes of externally encoded data, it is possible to effectively correct the loss of up to 54 scan lines.

[0058] Furthermore, while non-IP wireless transmission methods can transmit uncompressed video signals, WHDI transmission methods and WirelessHD transmission methods can also transmit video signals after compression (lossy compression). Lossy compression can reduce data size while maintaining quality and shorten processing time, thus enabling efficient data processing. During the video signal compression process (lossy compression), a few bits of information on the LSB (least significant bit) side are discarded. Therefore, in this embodiment, a data saving process is performed as a mechanism to avoid the effects of discarding a few bits of information on the LSB side during the video signal compression process (lossy compression).

[0059] Furthermore, since the retraction process is applied when the transmitting device T transmits to the receiving device R, taking into consideration the process of video signal compression (lossy compression), for example, if the transmitting device T transmits the video signal uncompressed without performing video signal compression, the retraction process (retraction unit 105) can be omitted.

[0060] <Description of the second control device> Figure 5 is a functional block diagram of the second control device 20 in this embodiment. The input side of the second control device 20 is connected to the receiving device R, and the output side is connected to the device D. A video signal (an IP multicast packet encapsulated with a video signal) is input to the second control device 20 from the receiving device R. The transmission paths between the receiving device R and the second control device 20, and between the second control device 20 and the device D, can be wired or wireless.

[0061] As shown in Figure 5, the second control device 20 is configured to include an input unit 201, a restoration unit 202, an internal code decoding unit 203, a deinterleaving unit 204, an external code decoding unit 205, a coupling unit 206, and a packet control unit 207. The second control device 20 corresponds to each process sequentially performed by the first control device 10 shown in Figures 3 and 4, and processes the data in the order of decoding, internal code decoding, deinterleaving, external code decoding, and coupling for the backup process, thereby extracting the IP multicast packet.

[0062] The input unit 201 is the input interface for the video signal transmitted from the receiving device R, and outputs the video signal to the restoration unit 202. The restoration unit 202 performs the process of restoring the internally encoded data from the video signal that has been bit-interleaved by the saving process on the transmitting side.

[0063] The internal code decoding unit 203 performs error correction processing based on the internal code parity bit included in the internal code data and generates data extracted in the scan line direction.

[0064] The deinterleaving unit 204 performs a deinterleaving process that rearranges the data extracted in the scan line direction in a direction perpendicular to the scan line, thereby generating externally encoded data arranged in the transmission order of the IP multicast packets.

[0065] The external code decoding unit 205 performs error correction processing based on the external code parity bit included in the external code encoded data after deinterleaving, and generates fixed-length data that constitutes an IP multicast packet.

[0066] The coupling unit 206 concatenates the decoded fixed-length data based on a synchronization pattern, and the packet control unit 207 extracts an IP multicast packet based on the concatenated fixed-length data group and outputs the IP multicast packet to device D.

[0067] <Specific example of encapsulating IP multicast packets with video signals> As described above, the IP multicast wireless transmission system of this embodiment encapsulates IP multicast packets provided by a data source (distribution provider) into a video signal format that can be transmitted using a non-IP wireless transmission method, and transmits them to the receiving side via the transmitting device T.

[0068] The format in which the video signal is encapsulated is arbitrary, but video signal standards such as HDMI and SDI (SD-SDI, MD-SDI) can be used. These video signals, for example, in the case of HDMI signals, use the TMDS (Transition Minimized Differential Signal) method, which is divided into four areas, with one area used as the clock storage area and the other three areas used as data storage areas.

[0069] In other words, a video frame that constitutes a video signal includes each region corresponding to multiple data storage areas. Taking an HDMI signal as an example, it has three regions: "TMDS DaTa 0 (B side)", "TMDS DaTa 1 (G side)", and "TMDS DaTa 2 (R side)". Thus, a video frame embedding an IP multicast packet can include multiple different data storage areas (data storage layers), and the IP multicast wireless transmission system of this embodiment utilizes these multiple data areas to encapsulate the IP multicast packet in a video signal.

[0070] In the following explanation, we will use an HDMI signal as an example and describe an example of utilizing three data areas corresponding to "TMDS DaTa 0 (B-side)", "TMDS DaTa 1 (G-side)", and "TMDS DaTa 2 (R-side)". However, encapsulation can be performed using multiple data areas conforming to the video signal standard, and this is not the only option. Also, while specific byte lengths are given as examples in the following explanation, these are not the only possible lengths. The lengths of various data, such as the byte length of IP multicast packets and fixed-length byte lengths, are arbitrary.

[0071] Figure 6 is a functional block diagram of the first control device 10, which encapsulates IP multicast packets in video signals corresponding to multiple data areas. Compared to the example in Figure 2, the data control unit 101 includes an area control unit 101a. The other components are the same as those in Figure 2 and are denoted by the same reference numerals.

[0072] Figure 7 illustrates the various processes involved in encapsulating IP multicast packets in a video signal that supports multiple data domains, and Figure 8 illustrates the internal encoding process involved in encapsulating IP multicast packets in a video signal that supports multiple data domains.

[0073] This explanation will describe an example of encapsulating an IP multicast packet in a 1920 x 1080 pixel video frame (frame rate of 60fps or 30fps, chroma subsampling of 4:4:4 or 4:2:2). First, if the IP multicast packet to be transmitted is 600 bytes long, the data control unit 101 divides it into three fixed-length data packets of 212 bytes each. In this example, it is divided into three fixed-length data packets, but it may also be divided into two or four or more fixed-length data packets. If there is any remainder in the divided fixed-length data packets, it is filled with NULL. Next, the data control unit 101 adds a synchronization pattern (4 bytes) to each fixed-length data packet to generate a fixed-length data packet of 216 bytes. Up to this point, the process is the same as the fixed-length division and synchronization pattern addition shown in Figure 3.

[0074] On the other hand, the region control unit 101a sets up multiple divided regions corresponding to the data storage area based on the format of the video signal that can be transmitted by a non-IP wireless transmission method. In the case of an HDMI signal, since it includes three data storage areas, three divided regions (first divided region (R side), second divided region (G side), and third divided region (B side)) are set up for these three data storage areas. The data control unit 101 divides each 216-byte fixed-length data into multiple parts. For example, one fixed-length data is divided in half, into a 108-byte first half-byte length data and a 108-byte second half-byte length data. Then, the data control unit 101 assigns each of the divided byte-length data to different divided regions.

[0075] Specifically, the first half of the fixed-length data is allocated to the first partitioned area, and the second half of the fixed-length data is allocated to the second partitioned area. This allocation process to partitioned areas is performed for each of the multiple fixed-length data, and the first half of the data from each of the multiple fixed-length data is aggregated in the first partitioned area, while the second half of the data is aggregated in the second partitioned area.

[0076] The external encoding unit 102 performs external encoding processing on each of the multiple byte-length data assigned to each divided region to generate an external code parity bit, and then concatenates the byte-length data with the external code parity bit corresponding to that byte-length data to generate externally encoded data. For example, RS encoding (120,108) processing is performed on 108-byte byte-length data to generate 12 bytes of external code parity bits, and 120-byte externally encoded data is generated for each byte-length data. The external encoding unit 102 performs this for each divided region (performing the external encoding processing shown in Figure 3 for each divided region).

[0077] The interleaving unit 103 operates similarly, performing the interleaving process shown in Figure 3 for each divided region. It rearranges the externally encoded data, which is arranged in the transmission order of the IP multicast packets, in a direction perpendicular to the scan lines of the video signal frame (vertical direction), and assigns the externally encoded data as pixels of the video signal. In this case, nine 120-byte-long externally encoded data files can be placed vertically from the left edge in a 1920x1080 resolution. Any number of these nine vertically arranged 120-byte-long externally encoded data files can be placed within the frame.

[0078] As described above, the interleaving unit 103 ensures that even if an entire scan line is lost due to a burst error, only one byte is lost in the 120-byte length of externally encoded data arranged perpendicular to the frame's scan lines. Therefore, it can be properly decoded by error correction processing based on the external code parity bit. In the case of 120-byte length of externally encoded data, a maximum of 54 scan line losses can be tolerated (effectively corrected) (((120-108)÷2)×(1080÷120)=54).

[0079] As shown in Figure 8, the internal encoding unit 104 generates a data sequence for each divided region by cutting out the externally encoded data, which has been rearranged in a direction orthogonal to the scan lines, in the direction of the scan lines. At this time, the data sequences corresponding to each of the multiple divided regions are concatenated, and the concatenated data sequence group is subjected to internal encoding processing (LDPC: encoding rate 2 / 3) to generate an internal code parity bit. After generating the internal code parity bit, the internal encoding unit 104 rearranges each data sequence to the corresponding divided region and assigns the generated internal code parity bit to a divided region (third divided region) different from the divided regions (first divided region, second divided region) to which byte-length data is allocated.

[0080] The backup unit 105 performs a backup process that swaps the vertical and horizontal order of the bits of the data for each divided region generated by the internal encoding unit 104, as well as for the internal encoding parity bit (the backup process shown in Figure 4 is performed for each divided region).

[0081] The output unit 106 converts each data sequence and the internal parity bit after the saving process into a video signal to be transmitted using the WHDI transmission method or the WirelessHD transmission method, and outputs it to the transmitting device T.

[0082] Figure 9 is a functional block diagram of a second control device 20 that encapsulates IP multicast packets in video signals corresponding to multiple data areas. Compared to the example in Figure 5, a synthesis unit 206a is provided between the external code decoding unit 205 and the coupling unit 206. The other components are the same as those in Figure 5 and are denoted by the same reference numerals.

[0083] The second control device 20 corresponds to each process sequentially performed by the first control device 10 shown in Figures 7 and 8, and performs decoding, internal code decoding, deinterleaving, and external code decoding for each of the multiple divided regions, and combines the byte length data assigned to the multiple divided regions in the combining unit 206a (combining the multiple divided regions to which byte length data is assigned).

[0084] The input unit 201 is the input interface for the video signal transmitted from the receiving device R, and outputs the video signal to the restoration unit 202. The restoration unit 202 performs a process to restore the video signal, which has been bit-interleaved by the saving process on the transmitting side, for each divided region.

[0085] The internal code decoding unit 203 performs error correction processing based on the internal code parity bit assigned to a partitioned area separate from the partitioned area to which the byte-length data is assigned, and generates a data sequence group by concatenating the data sequences corresponding to each partitioned area.

[0086] The deinterleaving unit 204 assigns the internally coded and decoded data sequence to the corresponding partitioned region, and for each partitioned region, performs a deinterleaving process to rearrange the data sequence cut out in the scan line direction in a direction orthogonal to the scan line, thereby generating the externally coded data arranged in the transmission order of the IP multicast packet.

[0087] The external code decoding unit 205 performs error correction processing based on the external code parity bit included in the external code encoded data after deinterleaving for each divided region, and generates byte length data.

[0088] The synthesis unit 206a integrates the byte-length data assigned to each divided region to generate fixed-length data. The joining unit 206 concatenates the synthesized fixed-length data. Then, the packet control unit 207 extracts an IP multicast packet based on the concatenated fixed-length data group and outputs the IP multicast packet to device D.

[0089] Although we have described the number of data storage areas in a video frame that constitutes a video signal in three ways, using an HDMI signal as an example, it is also possible to configure the system to allocate byte-length data to multiple divided areas in accordance with any video signal format (video signal standard) that can be transmitted by a non-IP wireless transmission system. In this case, since one divided area is used for the internal code parity bit, the fixed-length data can be divided into multiple byte-length data according to the number of remaining divided areas, and each divided byte-length data can be allocated to the remaining divided areas. [Explanation of Symbols]

[0090] 10. First control device (capsule device) 101 Data Control Unit 101a Region Control Unit 102 Outer encoding section 103 Interleaving Section 104 Inner encoder 105 Evacuation Area 106 Output section 20 (20A, 20B, 20C) Second control unit 201 Input section 202 Restoration Department 203 Internal code decoding unit 204 Deinterleaving Section 205 External code decoding unit 206a Synthesis Department 206 Joint 207 Packet Control Unit T Transmitter R Receiver Tt,Rt Wireless Communication Department D equipment

Claims

1. An IP multicast wireless transmission system that transmits IP multicast packets from a transmitting device to one or more receiving devices via unidirectional communication, The transmitting device and the receiving device are equipped with a wireless communication unit that transmits and receives video signals using WHDI transmission or WirelessHD transmission. A first control device that encapsulates the IP multicast packet in a video signal format that can be transmitted using the WHDI transmission method or the WirelessHD transmission method and outputs it to the transmitting device, The system includes a second control device that extracts the IP multicast packets from the video signal output from the receiving device, Data is transmitted using an FEC (Forward Error Correction) method, in which errors occurring in the transmission path between the transmitting device and the receiving device are corrected on the receiving device side. An IP multicast wireless transmission system characterized by the following features.

2. The first control device is An external encoding unit divides the IP multicast packet into predetermined fixed-length byte data, generates multiple fixed-length data, applies external encoding processing to each of these data to generate external code parity bits, and concatenates the fixed-length data with the external code parity bits corresponding to the fixed-length data to generate externally encoded data. An interleaving unit that rearranges each of the externally encoded data, which are arranged in the transmission order of the IP multicast packets, in a direction orthogonal to the scan lines of the video signal frame, and assigns the externally encoded data as pixels of the video signal, An internal encoding unit that extracts the externally encoded data, which has been rearranged in a direction perpendicular to the scan lines, in the direction of the scan lines, applies an internal encoding process to the extracted data to generate an internal encoding parity bit, and adds the internal encoding parity bit to the extracted data to generate internally encoded data, An output unit that converts the internally encoded data into a video signal to be transmitted using the WHDI transmission method or the WirelessHD transmission method and outputs it to the transmitting device, The IP multicast wireless transmission system according to claim 1, characterized by comprising the above.

3. The first control device is The data control unit divides the IP multicast packet into predetermined fixed-length byte data to generate multiple fixed-length data, and adds a synchronization pattern indicating the delimiter of the IP multicast packet to each fixed-length data, The external encoding unit generates an external code parity bit by performing an external code encoding process on each fixed-length data to which a synchronization pattern has been added, and generates the external encoded data by concatenating the fixed-length data to which the synchronization pattern has been added with the external code parity bit corresponding to the fixed-length data to which the synchronization pattern has been added. The system further includes a saving unit that performs a saving operation to swap the order of the vertical and horizontal bits of the internally encoded data. The output unit converts the data sequence after the backup process into a video signal to be transmitted using the WHDI transmission method or the WirelessHD transmission method and outputs it to the transmitting device. The IP multicast wireless transmission system according to feature 2.

4. The second control device is An internal code decoding unit performs error correction processing based on the internal code parity bit included in the internal code data and generates data extracted in the scan line direction, A deinterleaving unit performs a deinterleaving process to rearrange the data extracted in the scan line direction in a direction perpendicular to the scan line, thereby generating the externally encoded data arranged in the transmission order of the IP multicast packets. An external code decoding unit performs error correction processing based on the external code parity bit contained in the external code data after deinterleaving, and generates fixed-length data constituting the IP multicast packet. A concatenation unit that concatenates the decoded fixed-length data, A packet control unit that extracts the IP multicast packets based on a concatenated set of fixed-length data, The IP multicast wireless transmission system according to claim 2, characterized by comprising the above.

5. The first control device is A data control unit divides the IP multicast packet into predetermined fixed-length byte data to generate multiple fixed-length data, divides each of the multiple byte-length data into multiple parts, and assigns each of the divided byte-length data to a different partition area. An external encoding unit performs external encoding processing on byte-length data to generate external code parity bits, and then concatenates the byte-length data with the external code parity bits corresponding to the byte-length data to generate externally encoded data, for each divided region to which byte-length data is allocated. An interleaving unit performs interleaving for each divided region, rearranging the externally encoded data, which is arranged in the transmission order of the IP multicast packets, in a direction perpendicular to the scan lines of the video signal frame, and assigning the externally encoded data as pixels of the video signal. An internal encoding unit generates a data sequence by cutting out the externally encoded data, which has been rearranged in a direction orthogonal to the scan lines, in the direction of the scan lines for each divided region, and applies an internal encoding process to the data sequence group formed by concatenating the data sequences corresponding to each of the multiple divided regions to generate an internal encoding parity bit, and assigns the generated internal encoding parity bit to a divided region other than the divided region to which byte-length data is allocated, An output unit that converts each data sequence generated for each divided region and the internal code parity bit into a video signal to be transmitted using the WHDI transmission method or the WirelessHD transmission method and outputs it to the transmitting device, The IP multicast wireless transmission system according to claim 1, characterized by comprising the above.

6. The data control unit divides the IP multicast packet into predetermined fixed-length byte data to generate a plurality of fixed-length data, adds a synchronization pattern indicating the delimiter of the IP multicast packet to each fixed-length data, divides the fixed-length data with the synchronization pattern added into a plurality of byte-length data, and assigns each of the divided byte-length data to a different partition area. The first control device further includes a saving unit that performs a saving process to swap the vertical and horizontal order of the bits of the data for the data sequence of each divided region generated in the internal encoding unit and for the internal code parity bit of another divided region. The output unit converts each data sequence after the saving process and the internal code parity bit into a video signal to be transmitted using the WHDI transmission method or the WirelessHD transmission method, and outputs it to the transmitting device. The IP multicast wireless transmission system according to feature 5.

7. The second control device is An internal code decoding unit performs error correction processing based on the internal code parity bit assigned to another divided region and generates a data sequence group by concatenating data sequences corresponding to each of the multiple divided regions. A deinterleaving unit that assigns the internally coded and decoded data sequence to a corresponding partitioned region, performs a deinterleaving process for each partitioned region to rearrange the data sequence cut out in the scan line direction in a direction orthogonal to the scan line, and generates the externally coded data arranged in the transmission order of the IP multicast packet, An external code decoding unit performs error correction processing based on the external code parity bits included in the external code encoded data after deinterleaving for each divided region, and generates byte length data. A merging unit that integrates the corresponding byte-length data assigned to each divided region and generates fixed-length data, A coupling section that concatenates the synthesized fixed-length data, A packet control unit that extracts the IP multicast packets based on a concatenated set of fixed-length data, The IP multicast wireless transmission system according to claim 5, characterized by comprising the above.

8. An encapsulation device that receives IP multicast packets provided from a data source and encapsulates the IP multicast packets into a video signal format that can be transmitted using the WHDI transmission method or the WirelessHD transmission method, An external encoding unit divides the IP multicast packet into predetermined fixed-length byte data, generates multiple fixed-length data, applies external encoding processing to each of these data to generate external code parity bits, and concatenates the fixed-length data with the external code parity bits corresponding to the fixed-length data to generate externally encoded data. An interleaving unit that rearranges each of the externally encoded data, which are arranged in the transmission order of the IP multicast packets, in a direction orthogonal to the scan lines of the video signal frame, and assigns the externally encoded data as pixels of the video signal, An internal encoding unit that extracts the externally encoded data, which has been rearranged in a direction perpendicular to the scan lines, in the direction of the scan lines, applies an internal encoding process to the extracted data to generate an internal encoding parity bit, and adds the internal encoding parity bit to the extracted data to generate internally encoded data, An output unit that converts the internally encoded data into a video signal to be transmitted using the WHDI transmission method or the WirelessHD transmission method and outputs it, A capsule device characterized by being equipped with the following features.

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