JP2005102161A - Transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems that a transmission system is disadvantageous in costs and miniaturization when a digital HD video signal and a digital audio signal are transmitted while being optically multiplexed by an HDMI standard, and audio signals and control signals are superimposed in a blanking period but they are frequently useless in a transmission system of the HDMI standard. <P>SOLUTION: The transmission system omits blanking signals from vertical and horizontal synchronizing signals for video data while securing synchronized transmission between a transmission side and a reception side. To achieve this, the transmission system transmits first synchronizing data (HV) 2 of a partition identification signal for identifying vertical synchronization, second synchronizing data (HDp) 4 for identifying and synchronizing an effective video line, pixel data 11 for the effective video line, irreducibly required digital audio signals 9, 10, and digital auxiliary data 6, 8. Thus, the transmission system can reduce a transmission capacity, optimize a transmission format for optical wireless transmission, and decrease a transmission speed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a transmission system, and in particular, by combining and multiplexing an uncompressed baseband digital HD (High-Definition) video signal and a digital audio signal, a video signal format and a digital auxiliary control signal of the audio signal format, After serial transmission using wireless transmission means or optical signal transmission cable means and receiving the optical signal, it is possible to separate the video signal, audio signal / auxiliary control signal, and reproduce each video signal and audio signal The present invention relates to a transmission system in a video / audio optical wireless transmission apparatus or optical signal cable transmission apparatus.

  Conventionally, a transmission system that converts an uncompressed baseband digital HD video signal into an optical signal and serially transmits the signal is known (see, for example, Patent Document 1). Further, as a conventional transmission system for transmitting an uncompressed baseband digital HD video signal, there is a DVI (Digital Visual Interface) standard by wired cable transmission. The DVI standard is a standard mainly for digital video signal transmission in a personal computer, can handle only the three primary color signals of red (R), green (G) and blue (B), and transmits audio signals separately. There is a need. Therefore, in the DVI standard, it is necessary to connect an audio cable in addition to the video cable in order to be applied to AV equipment.

  As a connection method for solving this problem, there is a HDMI (High-Definition Multimedia Interface) standard as a new standard for AV. This HDMI standard is a standard that can handle component video signals and simultaneously transmit uncompressed audio signals.

  In this HDMI standard, for example, as shown in FIG. 4, the entire video signal 46 including the blanking interval of the horizontal synchronizing signal and the vertical synchronizing signal is transmitted, and the effective pixel number is 720 pixels and the effective line number is 480 lines. Data such as an audio signal and an auxiliary control signal is superimposed and transmitted in an area of a blanking section (horizontal direction 139 pixels, vertical direction 45 lines) 48 excluding the effective video signal area 47.

A transmission system that compresses and transmits an image signal and an audio signal in an optical transmission system is also known (see, for example, Patent Document 2). The conventional transmission system described in Patent Document 2 includes a transmission device that transmits supplied data such as images and sounds, and a reception device that is provided apart from the transmission device and receives the transmitted data. The data transmission apparatus is a data transmission apparatus, wherein the transmission apparatus shifts the transmission time by a predetermined amount in correspondence with a preset hierarchy and transmits the data in duplicate, and the reception apparatus transmits the data in duplicate. By receiving the generated data and layering the compressed data for each predetermined amount and storing it in the data storage means, even if the transmission path is interrupted, the layered data can be continuously combined by appropriately combining them. Output as data.
JP 2000-209622 A Japanese Patent No. 3329927 (second page)

  However, in the conventional transmission system described in Patent Document 1, the data transmission network is a computer network or an asynchronous transfer mode (ATM) network that conforms to IEEE 1394, and is a fiber transmission and cannot perform spatial transmission. The DVI standard is limited to wired cable transmission, and a separate audio cable is required in addition to the video cable to be applied to AV equipment.

  In addition, the conventional transmission system described in Patent Document 2 prevents transmission of video and audio signals from being interrupted when the transmission path is interrupted in a relatively short time. To transmit uncompressed baseband digital HD video signal and digital audio signal because data of block amount K (K is a real number larger than 1) times is compressed at regular intervals and transmitted intermittently. First, first in first out (FIFO) having a capacity K times the transmission block amount is required, the transmission clock is also required to be K times faster, and several Gbps is required, which is difficult to realize (however, In the case of a digital video signal or digital audio signal compressed by MPEG or the like, the capacity of the FIFO can be reduced, and the transmission speed can be kept low. That).

  On the other hand, the HDMI standard described above is a standard that can transmit component video signals and uncompressed audio signals at the same time, but TMDS (Transition Minimized Differential Signaling) technology is used as a common transmission technology adopted in the DVI standard. In this technology, all video signals including vertical synchronization and horizontal synchronization blanking signals are transmitted using 3 channel lines for transmission of video signals, audio signals and control signals. A single channel line is used for signal transmission, and a total of four channels are used to achieve high density and high speed transmission capacity.

  When this transmission signal is simply transmitted using an optical wireless transmission device, four optical wireless transmission lines must be secured or optically multiplexed and transmitted, which reduces costs and reduces the size of the device. Is disadvantageous. In addition, in order to realize high-speed transmission with a single light, it is necessary to increase the power of the transmitted radiation light in consideration of the conditions for ensuring the transmission distance at least the HDMI standard (10 m or more). This is disadvantageous in terms of downsizing the device.

  In addition, as shown in FIG. 4, the transmission system in the HDMI standard transmits all the vertical synchronization and horizontal synchronization including the blanking period, so that the audio signal and the control signal are superimposed on the blanking period. There is a lot of waste. In addition, as described above, in order to secure a transmission distance of 10 m or more by cable, all four channels are transmitted by the differential drive system using two signal lines, and one cable is used. Although they are collected, it is necessary to wire up to the display unit, which may be complicated.

  The present invention has been made in view of the above points, and an object thereof is to provide a transmission system capable of transmitting at least a digital HD video signal and a digital audio signal by a single light without transmitting unnecessary signals as much as possible. And

  Another object of the present invention is to provide a transmission system capable of transmitting at least a digital HD video signal and a digital audio signal using an inexpensive and small device.

  In order to achieve the above object, the present invention multiplexes a digital auxiliary signal containing auxiliary information related to a video format, an audio format, etc. together with a digital video signal and a digital audio signal at an uncompressed baseband level and serially transmits them. A first storage means for storing pixel data of a digital video signal for each predetermined unit section, and an audio sample unit with a sampling frequency synchronized with a master clock oscillator for transmission processing. Second storage means for storing predetermined unit sections, third storage means for storing digital auxiliary signals, first synchronization data defined as vertical synchronization signal synchronization data for digital video signals, Second synchronization data defined as synchronization data for valid line identification of a digital video signal; A plurality of lines in which a digital video signal read from the first storage means, a digital audio signal read from the second storage means, and a digital auxiliary signal read from the third storage means are synthesized in time series in a predetermined order. The transmission signal generating means for generating the transmission signal comprising the above and the output means for serially transmitting and outputting the transmission signal output from the transmission signal generating means.

  Here, the transmission signal generation means reads a predetermined number of bits of the digital auxiliary signal from the third storage means following the first synchronization data, and synthesizes the signal in time series as the transmission signal of the first line. Subsequently to the second synchronization data, a signal obtained by reading out a predetermined number of bits of the digital auxiliary signal from the third storage means and synthesizing in a time series is used as a transmission signal of the second line, and from the third line to the predetermined line. Each of the transmission signals of the plurality of lines includes, following the second synchronization data, a digital audio signal sample data amount M (M: natural number) of the digital audio signal that needs to be transmitted per field from the second storage means. After sequentially reading the data section L (L: natural number) obtained by dividing by the effective line number N (N: natural number), the effective pixel data in each line of the digital video signal from the first storage means Sequentially read out chronologically synthesized, characterized in that the signals which eliminated the blanking signal.

  In the present invention, the transmission of the blanking signal in the vertical synchronizing signal and the horizontal synchronizing signal of the video is eliminated, and at least the synchronizing transmission between transmission and reception is ensured. And transmitting the second synchronization data, which is a separation identification signal that enables identification of the effective line synchronization of the video, and the digital auxiliary data including the pixel data of the effective line section and the minimum necessary digital audio signal. The transmission rate can be reduced by reducing the capacity and optimizing the transmission format for optical wireless transmission.

  As an example, the above-mentioned digital video signal is a 750p signal (number of effective video signal lines 768), and 24 bits / 2ch per field at the time of component video signal, the maximum number of samples that can be handled as an audio signal 420 (= 56 bytes × 45 lines / (3 bytes × 2ch)), horizontal code is 8 bytes of error correction generation code by Reed-Solomon, horizontal block is 48 lines / 64 bytes (including ECC 8 bytes), error detection code by vertical code is 3 bytes , If 2 blocks are transmitted as 64/3 bytes, the sample data amount M is 6144 bytes = ({(56 + 8) bytes × 45 lines + 64 × 3 bytes} × 2 blocks), and the digital video signal Since the number of effective lines N is 768 lines, the data section L is 8 (= 6 44/768) and a.

  In order to achieve the above object, the present invention provides a digital video signal that is to be displayed by a progressive scanning method, and the digital audio signal is composed of a plurality of lines from the third line of the transmission signal to a predetermined line. Data classification obtained by dividing the amount of sample data obtained by dividing the amount of sample data obtained by adding an error correction code to a digital audio signal that needs to be transmitted per field by one-half the number of effective lines L is sequentially transmitted. According to the present invention, the reproduction delay of the digital audio signal generated due to the error correction calculation using the error correction code on the receiving side can be made within two fields.

  In order to achieve the above object, according to the present invention, a digital video signal is a video signal to be displayed by an interlace scanning method, and a digital audio signal in a plurality of lines from the third line to a predetermined line of a transmission signal. Is obtained by dividing the amount of sample data obtained by dividing an amount of sample data obtained by adding an error correction code into a digital audio signal that needs to be transmitted per field by one-half the number of effective lines. The first half data section and the second half data section are combined and transmitted on each line. According to the present invention, the reproduction delay of the digital audio signal generated due to the error correction calculation using the error correction code on the receiving side can be made within 3 fields.

  In order to achieve the above object, according to the present invention, the transmission signal generator adds time-series special data for identifying whether the field is an even field or an odd field after the first synchronization data, A transmission signal of the first line to which the auxiliary signal is added is generated, and after the second synchronization signal, the special data which is the third auxiliary synchronization data is added in time series, and then the digital auxiliary signal or the digital audio signal In addition, a transmission signal from the second line to which a digital video signal is added is generated.

  In order to achieve the above object, according to the present invention, the transmission signal generating means includes a sample data amount of a digital audio signal that needs to be transmitted per field and a read data amount of effective pixel data in a plurality of lines of the digital video signal. On the other hand, the deficient data amount is padded with null data. In this invention, the video signal format that can be transmitted is fixed as the maximum transmission format, and in the case of a video signal corresponding to the transmission capacity below that, the video signal and the audio signal are subjected to padding processing by null data. It is.

  In order to achieve the above-mentioned object, the present invention provides a transmission signal generating means from the greatest common divisor satisfying the condition of an integral multiple of the sampling frequency of the digital audio signal and satisfying the number of effective transmission lines of the digital video signal. A transmission signal is generated using the calculated frequency as a master clock frequency.

In order to achieve the above object, according to the present invention, the output means performs 8-bit / 10-bit parallel conversion on the transmission signal output from the transmission signal generation means, and then performs parallel / serial conversion to transmit serially. It is characterized by that.
Further, the present invention is characterized in that a plurality of special codes are assigned to at least one of the first and second synchronization data, and each special code represents bit data.
Furthermore, the present invention assigns a plurality of special codes to at least one of special data for identifying whether the field is an even field or an odd field and the special data that is the third auxiliary synchronization data, and each special code represents bit data indicating information. It is characterized by that.

  According to the present invention, it is possible to identify vertical synchronization in order to eliminate transmission of a blanking signal in a vertical synchronization signal and a horizontal synchronization signal of video and to ensure synchronization transmission between transmission and reception at a minimum. Synchronization data, second synchronization data that is a segment identification signal that enables identification of video effective line synchronization, pixel data in an effective line section, sample data of a digital audio signal that needs to be transmitted per field, and at least The transmission capacity can be reduced by transmitting digital auxiliary data relating to limited video signals and audio signals, and the transmission rate can be reduced by optimizing the transmission format for optical wireless transmission.

  As a result, for example, 750p and 1080i component video (4: 2: 2) quality class uncompressed baseband digital HD video transmission can be optically transmitted at about 1.27 Gbps (for reference, a 750p component including a blanking interval). In the case of direct optical transmission of video, a transmission speed of about 1.49 Gbps is required), considering the current optical wireless transmission capability with single light and deployment to general AV equipment, and the transmission distance is In realizing reliable transmission of 10m or more, this transmission speed is greatly reduced, and it is possible to secure a margin for optical wireless transmission without increasing the circuit scale of transmission and reception, and realization of optical wireless transmission using a single light. Is possible.

  In addition, according to the present invention, the format of a video signal that can be transmitted is fixed as the maximum transmission format, and in the case of a video signal corresponding to a transmission capacity lower than that, both the video signal and the audio signal are subjected to padding processing using null data. Thus, if the vertical synchronization signal is the same, it can be transmitted in the same transmission format without changing the system, and synchronized reproduction of the video signal and the audio signal can be guaranteed.

Furthermore, according to the present invention, the frequency master clock calculated from the greatest common divisor satisfying the condition that the master clock frequency for transmission processing satisfies an integer multiple of the sampling frequency of the audio signal and the number of effective transmission lines of the video signal. Therefore, it is possible to simplify the synchronous reproduction process of the video signal and the audio signal, and the synchronous reproduction circuit of the video signal and the audio signal can be realized on a small scale.
Furthermore, according to the present invention, a plurality of special codes are allocated to at least one of the first and second synchronization data and the special code, and each special code represents bit data indicating information, so that the transmission band is widened. New information can be added and transmitted.

<First Embodiment>
Next, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows a signal format transmitted in the first embodiment of the transmission system according to the present invention. The signal format 1 of the first embodiment shown in FIG. 1 relates to a transmission format equivalent to 750p, which is a typical digital HD video signal by the progressive scanning method. Here, the number of effective pixels in the horizontal direction is 1366 pixels, A signal format with 768 effective lines is shown.

  That is, assuming that the frequency of the vertical synchronization signal is 59.94 Hz (= 60 Hz × 1000/1001), the number of effective lines of the video is 768, the number of effective pixels per effective line is 1366 pixels, and the configuration data word of one pixel. A signal that superimposes and transmits audio data with a sampling frequency of 48 kHz, level resolution of 24 bits, and 2ch (L / R) on a digital component video signal (4: 2: 2) of 2 bytes (16-bit word). Indicates the format.

  In the signal format of this embodiment, it is assumed that 8-bit / 10-bit parallel / serial conversion on the transmission side and serial / parallel conversion on the reception side are handled in units of 16-bit words, and parallel data is written to the memory. A clock 20 times (= 16 bits × 10B / 8B) of the master clock used for reading is used for serial transmission.

  In addition, at the beginning of the line transmission, always have one vertical synchronization identification synchronization data (hereinafter also referred to simply as synchronization data) (HV) 2 and one special data (HF) 3 character. To transmit. Special data (HF) 3 is special data for identifying even and odd fields.

  The first line is an area for transmitting auxiliary control data (CTL1) 6 such as an image format, and the vertical of predefined synchronization data (HV) 2 for ensuring vertical synchronization between transmission and reception first. Synchronous identification characters are serially transmitted, and then either one of the two types of special data (HF) 3 defined in the even field (“HFe”) / odd field (“HFo”) identification special data is serially transmitted. Thereafter, 8-bit word string data of auxiliary control data (CTL1) 6 stored and set in advance in the memory is read in units of 16-bit words, and serially transmitted after 8B / 10B conversion.

  At the end, CRCC 16-bit word data 7, which is a data transmission error detection code, is added to the data string calculated when the auxiliary control data (CTL1) 6 is read, and serial transmission is performed after 8B / 10B conversion. The special data (HF) 3 needs to be transmitted alternately between the even field (“HFe”) and the odd field (“HFo”) according to the transmission image information when transmitting the interlaced video format signal.

  The second line is an area for transmitting the same auxiliary control data (CTL2) 8 as that of the first line. First, effective line identification synchronization data (defined in order to ensure synchronization of effective lines between transmission and reception) ( (Hereinafter simply referred to as synchronization data) (HDp) 4 effective line identification characters are serially transmitted, and then two types of predefined special data for auxiliary synchronization data (hereinafter also simply referred to as special data) (HDs) After serial transmission of 5, the same data as in the first line is synthesized in time series. The second line here is the same auxiliary control data as the first line, and may be omitted.

In FIG. 1, area 9 is a half field of the first half of the audio signal transmission block, area 10 is a half field of the latter half of the audio signal transmission block, and area 11 is an effective data transmission area of the video signal. In addition, including these areas, the areas and the signals in them may be indicated by the same reference numerals.
From the third line, the audio signal 9 and the video signal 11 are transmitted. First, the synchronization data (HDp) 4 and the special data (HDs) 5 are sequentially synthesized in time series in the same manner as in the second line, and then the half of the first half of the 2ch audio signal transmission block having a sampling frequency of 48 kHz and a level resolution of 24 bits. After the audio signals 9 for fields are synthesized in time series for 8 bytes, the digital component video signal (YUV (4: 2: 2)) 11 in which the number of data words of one pixel is 2 bytes (16-bit words) 11 The effective pixels of 1366 × 2 bytes are synthesized, and further, the CRCC 7 for data transmission error detection for the transmission data sequence calculated at the time of reading the audio signal and the video signal is synthesized in a 2-byte time series. Here, the CRCC calculation coping range may be limited to video signals only.

  The 383 lines from the 4th line to the 386th line repeatedly synthesize the audio signal 9 and the video signal 11 in the same manner as the 3rd line. Subsequently, from 387 lines to 770 lines, as in the 3rd to 386 lines, the time series composition of 8 bytes of the audio signal 10 and 1366 × 2 bytes of the video signal 11 per line is repeated for 384 lines. Synthesize. However, the audio signal 10 of 384 lines from the 387th line to the 770th line is an audio signal corresponding to ½ field in the latter half of the 2-channel audio signal transmission block having a sampling frequency of 48 kHz and a level resolution of 24 bits.

  Note that error correction processing for audio signals requires error correction code calculation processing in a certain block data unit in advance at the time of transmission, and the error correction calculation processing can be performed for the first time after receiving the block data unit on the receiving side. Become. As a result, the occurrence of signal reproduction delay is inevitable. Also, the block data unit cannot be made too small considering the error correction capability.

  For this reason, in this embodiment, the audio signal in one field is divided into two parts, the audio signal transmission block 9 for the first half of the field and the audio signal transmission block 10 for the second half of the field. The goal is to reduce the playback delay due to transmission and reception within 2 fields. Further, in the audio signal transmission blocks 9 and 10, an extra data transmission area is padded with null data and transmitted in consideration of video signal transmission.

  The transmission line of the last 771 line satisfies the condition that the master clock frequency for transmission processing is an integral multiple of the sampling frequency of the audio signal, and simplifies the synchronous reproduction processing of the video signal and the audio signal. This is an extra data transmission amount that occurs when the frequency is calculated from the greatest common divisor satisfying the number of effective transmission lines. For this reason, since the transmission line is an invalid data area, after synthesizing the synchronization data (HDp) 4 and the special data (HDs) 5 in time series, the null data obtained by padding the extra data transmission is 616 × 2 The bytes are synthesized. CRCC arithmetic processing data is not added to the null data.

  The audio signal format to be transmitted is set to have a sampling frequency of 48 kHz, a level resolution of 24 bits, and a transmission capacity of 2 ch (L / R). However, by setting the sampling frequency to 48 kHz and the level resolution of 16 bits, the transmission format is set. It is also possible to transmit a 3ch (L / R / Center) signal without changing.

  The transmission signal format of the present invention in FIG. 1 is illustrated with 8 bits (1 byte) as a minimum unit. However, as described later, when transmitting a transmission signal as an optical signal, 1 byte is changed to 10 bits. Convert and transmit. Therefore, in the case of an optical signal, the synchronous data (HV) 2, special data (HF) 3, synchronous data (HDp) 4 and special data (HDs) 5 are shown as 1 byte. Each is converted into 10 bits and transmitted. The same applies to video signals and audio signals.

  8B / 10B (8 bits / 10 bits) conversion for converting 1 byte into 10 bits is considered as code conversion that avoids DC offset at the time of reception in transmission signal quality, and is widely known. In addition, 256 types of 8-bit data combinations are defined and transmitted out of 1024 types in 10-bit conversion, and several types of data other than 256 types are defined as special characters. Stable reception is possible by specifically defining the clock generation character.

  Next, a first embodiment of the transmission system of the present invention that transmits and receives signals of the above signal format will be described. FIG. 2 shows a block diagram of a first embodiment of a transmission system according to the present invention. In this embodiment, an optical transmission processing block 20 that generates an optical signal having the signal format shown in FIG. 1 from the input digital video signal and digital audio signal and optically transmits the optical signal, and an optical signal having the signal format described above is transmitted. It comprises an optical reception processing block 30 that receives and restores the original digital video signal and digital audio signal.

  In this embodiment, the 750p signal, which is an uncompressed baseband digital video signal by the progressive scanning method in the signal format of FIG. 1 described above, is transmitted and received together with the audio signal, and the interlace scanning is performed in the signal format of FIG. 3 to be described later. In some cases, a 1080i signal, which is an uncompressed baseband digital video signal according to a method, is transmitted and received together with an audio signal. In this case, either the progressive scanning video signal transmission or the interlace scanning video signal transmission may be uniquely determined in advance according to the display specifications of the system, or the system switches the switch. It is also possible to incorporate information and transmission side video processing information in the auxiliary control data 6 and 8 (CTL1, CTL2) and transmit them.

  Next, the operation of this embodiment when transmitting / receiving a signal of the signal format of FIG. 1 will be described. A digital video signal input terminal (hereinafter also simply referred to as an input terminal) 17 is a vertical synchronizing signal of 59.94 Hz, with 768 effective lines and 1366 effective pixels per effective line. An uncompressed baseband level digital component video signal (YUV (4: 2: 2)) having a word number of 2 bytes (16-bit word) is input in 8-bit parallel and a video memory 21 configured by FIFO, video The signals are supplied to the memory writing / reading control unit 22 and the audio memory 24, respectively, and are written into the video memory 21 line by line based on a control signal from the video memory writing / reading control unit 22.

  On the other hand, a digital audio signal input terminal (hereinafter also referred to simply as an input terminal) 18 receives a digital audio signal having a sampling frequency of 48 kHz, a level resolution of 24 bits, and 2ch (L / R), and is configured by a FIFO. The audio signal is supplied to the audio memory 24 in a 24-bit parallel manner, and sequentially written in synchronization with the sampling frequency of the audio signal synchronized with the transmission processing master clock oscillator output from the audio signal clock oscillator 23.

  The written digital audio signal is divided and managed into two blocks (audio signals 9 and 10) shown in FIG. 1 for each field of the digital video signal input from the input terminal 17, and the audio signal sample for each block is recorded. The number is written to the audio memory 24. Further, for each block, a digital audio signal is read from the audio memory 24 and supplied to the error correction code generation processing unit 25, where a transmission error detection code and an error correction code are generated and written to the audio memory 24. It is.

  At the time of transmission of the first optical signal on the first line, as shown in FIG. 1, synchronization data 2 for vertical synchronization identification of predefined synchronization data (HV) for ensuring vertical synchronization between transmission and reception, and FIG. As shown in FIG. 4, any one of the special data for identification 3 of the even field (“HFe”) / odd field (“HFo”) of two types of special data (HF) defined in advance is the special data addition control unit 2A. Is converted to 10-bit parallel data by the 8-bit / 10-bit conversion unit 2B and further supplied to the parallel / serial conversion unit 2C, where it is converted into serial data, and then converted into an optical signal by the optical transmission module 2D. It is converted and transmitted to the optical wireless transmission path 41.

  Subsequently, as shown in FIG. 1, 8-bit word string data of auxiliary control data (CTL1) 6 stored and set in advance in the video / audio control auxiliary data processing unit 26 is read in units of 16-bit words. After being supplied in parallel to the 8-bit / 10-bit conversion unit 2B through the video / audio synthesis unit 28, the 16-bit word is converted into 20-bit parallel data, and further converted into serial data by the parallel / serial conversion unit 2C. Then, it is converted into an optical signal by the optical transmission module 2D and transmitted to the optical wireless transmission line 41 (however, FIG. 1 shows serial data before 8-bit / 10-bit conversion).

  At the end of the first line, based on the auxiliary data (CTL1) 1366 × 2 bytes supplied to the video / audio synthesizer 28, the CRCC generator 2E generates it and supplies it to the video / audio synthesizer 28. A 2-byte data transmission error detection code (CRCC) 7 is read in parallel from the video / audio synthesizer 28 in units of 16 bits, and an 8-bit / 10-bit converter 2B, a parallel / serial converter 2C, and an optical transmission module It is converted into an optical signal through 2D and transmitted to the optical wireless transmission line 41 as shown in FIG. 1 (however, FIG. 1 shows serial data before 8-bit / 10-bit conversion). CRCC 7 is a transmission error detection code that is completed for each line.

  In the second line, an optical signal having the same format as that of the first line is transmitted to the optical wireless transmission line 41. From the third line, the audio signal 9 and the video signal 11 are transmitted. First, the synchronization data (HDp) 4 and special data (HDs) 5 sequentially output from the special data addition control unit 2A in the same manner as the second line are serially transmitted through a path, and then predetermined in the audio memory 24. The audio signal 9 to which the error correction code is added from the data section is time-compressed in units of 16-bit words and read out, and then supplied in parallel to the 8-bit / 10-bit conversion unit 2B through the video / audio synthesis unit 28. Here, it is converted into parallel data in units of 20-bit words. This 20-bit word unit parallel data is converted into serial data by the parallel / serial converter 2C, then converted into an optical signal by the optical transmission module 2D, and transmitted to the optical wireless transmission line 41 as shown in FIG. (However, FIG. 1 shows serial data before 8-bit / 10-bit conversion).

  Further, the video signal data 11 is read out in units of 16 bits by time expansion in units of pixel data from the video memory 21 dedicated to video signals, based on the readout clock from the video memory write / read controller 22. The signal is supplied to the 8-bit / 10-bit conversion unit 2B through the video / audio synthesis unit 28. The video signal data 11 input by the 8-bit / 10-bit converter 2B is converted from 16-bit pixel data to parallel data in units of 20 bits, and further converted to serial data by the parallel / serial converter 2C. It is converted into an optical signal by the optical transmission module 2D and transmitted to the optical wireless transmission line 41 as shown in FIG. 1 (however, FIG. 1 shows serial data before 8-bit / 10-bit conversion).

  At the end of the third line, when the audio signal and the video signal are read, the data transmission error detection code for the transmission data string calculated from the 4 × 2 byte audio signal and the 1366 × 2 byte video signal data by the CRCC generator 2E is displayed. One CRCC 16-bit word data 7 is supplied to the optical transmission module 2D through the above-described path, where it is converted into an optical signal and transmitted serially to the optical wireless transmission path 41 as shown in FIG. FIG. 1 shows serial data before 8-bit / 10-bit conversion).

  From the 4th line to the 770th line, the same readout as the above 3rd line is performed, and optical signals having the same signal arrangement as the 3rd line are transmitted by optical wireless. In the last line 771, after the synchronous data (HDp) 4 converted to 10 bits and the special data (HDs) 5 converted to 10 bits are wirelessly transmitted in time series, the audio signal transmission block (9, 10) As shown in FIG. 1, 616 bytes of null data in the area 12 in which extra data transmission has been padded are transmitted serially to the optical wireless transmission line 41 as shown in FIG. The padded null data 12 is obtained by controlling whether valid data is input or null data is added according to the transmission format in the transmission timing generation circuit 29.

  Next, the operation of the optical reception processing block 30 in FIG. 2 will be described. In the optical reception processing block 30, in accordance with a vertical synchronization identification trigger signal (first synchronization data (HV) 2), a digital video signal and a digital auxiliary signal including a digital audio signal transmitted serially are respectively dedicated video memories. 3A, once stored in the audio memory 3D, the audio signal is subjected to predetermined signal processing such as error correction, and then sequentially used by the audio signal reproduction clock generated based on the sampling frequency information on the transmission side by the digital auxiliary data. Is read out and reproduced in the sampling period by time expansion. The number of samples of the audio signal to be reproduced is synchronized with the video by continuously reproducing the number of samples simultaneously transmitted for each block (9, 10).

  On the other hand, the video signal is synchronized with the rescaling clock in the vertical synchronization based on the transmitted vertical synchronization identification trigger signal, and includes the blanking interval according to the video format based on the digital auxiliary data. In addition, a horizontal synchronization signal is added, and pixel data for each effective line is sequentially read out from the video memory 3A by time compression, and synchronized reproduction is performed by rescaling to solve the above-described problem.

  That is, the optical signal in the format of FIG. 1 transmitted through the optical wireless transmission path 41 is received and photoelectrically converted by the optical reception module 31 in the optical reception processing block 30 and then converted into parallel data by the serial / parallel converter 32. And is supplied to the 10-bit / 8-bit conversion unit 33, and the input 10 bits are converted into 8 bits and output.

  The special data monitoring control unit 34 monitors the synchronization data (HV) 2 which is a single vertical synchronization identification trigger signal added to the head of the line transmission, and this synchronization data (HV). When 2 is detected, an even field and an odd field are identified from the next one special data (HF) 3 and the reception timing signal output from the reception timing generation circuit 35 is controlled. On the other hand, of the signals output from the serial / parallel converter 32, based on synchronization data (HDp) 4 which is a segment identification signal that enables identification of effective line synchronization of video allocated as predetermined synchronization data. A self clock is generated from the self clock oscillator 37. The self clock is supplied to the reception timing generation circuit 35 and the video memory write / read control unit 39, respectively. The synchronous data (HDp) 4 is also used to satisfy the self-clock correction function at the time of reception by transmitting it periodically for each effective line.

  The received signal obtained by converting 10 bits into 8 bits by the 10-bit / 8-bit converter 33 is input in parallel to the video / audio separator 36 in units of 16-bit words. Based on the reception timing signal, the video signal data 11, the audio signal data 9 and 10, and the auxiliary control data (CTL 1) 6 and (CTL 2) 8 are separated, and the video signal data 11 is a video memory 3 A configured by FIFO. The audio signal data 9, 10 are supplied to the audio memory 3D configured by FIFO, and the control auxiliary data (CTL1) 6, (CTL2) 8 are supplied to the video / audio control auxiliary data monitoring unit 3C. .

  The audio signal data 9 and 10 written in the audio memory 3D are divided and managed in two blocks for each field of the transmitted video signal data 11, and the audio signal data 9 from the audio memory 3D for each block. 10 is read out and supplied to the error correction processing unit 3E, and after error correction processing is performed using the error detection code and the error correction code, they are written back to the audio memory 3D.

  Further, the reception-side self-clock oscillator 37 synchronized with the transmission-side transmission processing master clock oscillator 27 generates a synchronized reproduction clock signal with the transmission-side sampling frequency by the audio signal reproduction clock oscillator 38, and this clock signal Based on the number of channels on the transmission side, the number of sample valid bits, etc. included in the auxiliary control signals CTL1 and CTL2 received from the video / audio control auxiliary data monitoring unit 3C, the reproduced audio after the error correction processing from the audio memory 3D The signal data 9 and 10 are time-expanded so as to have the original time axis, read out in a sampling cycle, and output to the digital audio signal output terminal 43.

  Also, based on the auxiliary control signals (CTL1) 6 and (CTL2) 8 received from the video / audio control auxiliary data monitoring unit 3C, information such as a video format and display unit setting information for setting and controlling the reproduction display unit side is stored. Based on the information from the rescaling video timing generation circuit 3B, the video memory writing / reading control unit 39 performs writing and reading control to the video memory 3A.

  Here, as shown in FIG. 4, a normal video signal is input / output in a uniquely determined format including blanking, and is treated as a signal that can be displayed if transmitted to the display unit as it is. However, in the transmission format of the present embodiment, as shown in FIG. 1, the blanking portion is omitted, and the video signal portion is time-axis compressed and transmitted to reduce the transmission capacity. An output signal to a display unit (not shown) needs to add blanking and extend the time axis of received video data. Therefore, the rescaling video timing generation circuit 3B performs rescaling for adding a vertical synchronizing signal and a horizontal synchronizing signal including a blanking signal and extending the time axis of the received video signal data.

  The vertical synchronization signal and the horizontal synchronization signal including the blanking signal output from the rescaling video timing generation circuit 3B are adjusted to the display unit in units of pixel data based on the read clock from the video memory write / read control unit 39. The pixel data of the effective line section read out from the video memory 3A line by line in units of 16 bits of one pixel on the time axis are combined and output to the digital video signal output terminal 42.

  As described above, according to the present embodiment, although a transmission section in which padding processing with extra null data is generated occurs, transmission of an unnecessary signal is not performed as much as possible by stopping transmission in the synchronous blanking section. 750p component video (4: 2: 2) quality class uncompressed baseband digital HD video transmission is reduced to about 1.27 Gbps by adding a superimposition processing section of the audio signal to the pixel data transmission of only the effective line section. Optical transmission is possible.

  Incidentally, in the case of directly optically transmitting a 750p component video including a blanking section, a transmission speed of about 1.49 Gbps is required. Considering the current optical wireless transmission capability with single light and deployment to general AV equipment, and realizing reliable transmission with a transmission distance of 10 m or more, this transmission speed is greatly reduced. The circuit scale does not increase, it is possible to secure a margin for optical wireless transmission, and optical wireless transmission using a single light can be realized.

  Further, according to the present embodiment, the frequency calculated from the greatest common divisor that satisfies the condition that the master clock frequency for transmission processing is an integral multiple of the sampling frequency of the audio signal and satisfies the number of effective transmission lines of the video signal. By using the master clock, it is possible to simplify the synchronous reproduction process of the video signal and the audio signal, and a synchronous reproduction circuit of the video signal and the audio signal can be realized on a small scale.

  Furthermore, the video signal format that can be transmitted is fixed as the maximum transmission format, and in the case of a video signal corresponding to a transmission capacity lower than that, the video signal and the audio signal are subjected to padding processing with null data, so that the vertical synchronization signal Can be transmitted in the same transmission format without changing the system, and there is an advantage that the synchronized reproduction of the video signal and the audio signal can be guaranteed. At least the digital HD video signal and the 720p or 480p video signal of 750p or less can be covered by the first embodiment.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. The present embodiment relates to transmission of 1080i, which is a typical digital HD video signal by the interlace scanning method. FIG. 3 shows a signal format transmitted in the second embodiment of the transmission system according to the present invention, and the same parts as those in FIG.

  The signal format 13 shown in FIG. 3 relates to 1080i video format transmission, assuming that the frequency of the vertical synchronization signal is 59.94 Hz (60 Hz × 1000/1001), the number of effective video lines is 540 × 2, and the effective line is one. The number of effective pixels per pixel is 1920 pixels, and the number of constituent data words per pixel is 2 bytes (16-bit words). The audio signal has a sampling frequency of 48 kHz, a level resolution of 24 bits, A format for superimposing and transmitting 2ch (L / R) audio data is shown.

  In the second embodiment, as in the first embodiment, 8-bit / 10-bit parallel / serial conversion on the transmission side and 10-bit / 8-bit serial / parallel conversion on the reception side are performed in units of 16-bit words. Therefore, a clock 20 times (= 16 bits × 10B / 8B) of a master clock used for writing / reading parallel data to / from the memory is used for serial transmission.

  In addition, since the total transmission capacity in this embodiment is smaller than the transmission capacity in the first embodiment, as shown by 14 and 15 in the signal format 13 in FIG. By performing padding processing, the total transmission capacity does not change the capacity of the first embodiment, and the block transmission including the condition for completing the necessary number of pixels per line by one line transmission and error correction of the audio signal Is realized on the condition that compatibility with the first embodiment is ensured.

  In FIG. 3, the first line shows the auxiliary control data such as the vertical synchronization identification character of the synchronization data (HV) 2, the special data (HF) 3, and the image format, as in the first embodiment. (CTL1) 6 and CRCC 16-bit word data 7 which is a transmission error detection code for the data sequence calculated at the time of reading the auxiliary control data are arranged in this order, and 8-bit / 10-bit (8B / 10B) conversion is performed on them. After that serial transmission is performed.

  Since this video signal is an interlaced scanning signal and the 1080i signal 11 and the audio signals 9 and 10 are transmitted for each field according to this signal format, the special data (HF) 3 is an even field according to the transmission image information. (HFe) and odd field (HFo) need to be transmitted alternately in field units. The second line is an area for transmitting the same auxiliary control data (CTL2) 8 as the first line, and serial transmission similar to that of the first embodiment is performed.

  From the third line, audio signal block (1/2) 9 and audio signal block (2/2) 10 and video signal data 11 are transmitted. Here, the difference from the first embodiment is that the number of effective lines that need to be transmitted per field in this video format is 543, so the effective line direction (vertical synchronization) is the same as in the first embodiment. Two audio signal blocks cannot be transmitted continuously in the line direction. For this reason, as shown in FIG. 3, the format is a format in which transmission is simultaneously performed in the effective pixel transmission direction (horizontal synchronization line direction).

  As with the second line, the synchronization data (HDp) 4 and special data (HDs) 5 are headed, and the audio signal block (1/2) 9 to which the error correction code has been added is stored in the audio signal dedicated / memory (FIFO) area. Further, 8 bytes of time-compressed data are read from a predetermined data section in units of 16-bit words, and serially transmitted after 8B / 10B conversion. Thereafter, a transmission process for 8 bytes is similarly performed on the audio signal block (2/2) 10 to which the error correction code is added.

  Further, data reading by time expansion is performed for 1920 × 2 bytes in pixel data units from the video signal dedicated memory (FIFO), and serial transmission is performed after 8B / 10B conversion. Finally, 2 bytes of 16-bit word data 7 of CRCC for transmission error detection are added to the transmission data sequence calculated when the audio signals 9 and 10 and the video signal 11 are read, and serial transmission is performed after 8B / 10B conversion. Here, the calculation coping range of CRCC 7 may be limited only to the video signal.

  Similar to the third line, the same transmission processing is performed up to the 386th line. Subsequently, from the 387th line to the 542st line, the 8 bytes of null data 14 padded per line, the 8 bytes of padded null data 15 audio signal, and 1920 × 2 bytes of video Serial transmission of the signal data 11 after 8B / 10B conversion is repeated for 156 lines.

  In the present embodiment, since the audio signal blocks 9 and 10 cannot be divided and transmitted in one field, the reproduction delay due to transmission / reception is set to be within three fields. In the audio signal blocks 9 and 10, the extra data transmission area is padded with the null data 14 and 15 and transmitted in the same manner as in the first embodiment in consideration of video signal transmission.

  The 543rd to 547th lines are the difference of the effective transmission capacity in this embodiment with respect to the total transmission capacity in the first embodiment, and are unnecessary data areas. In addition, both the audio signals 9 and 10 and the video signal 11 are padded with null data 16 and serial transmission is performed after 8B / 10B conversion. However, the CRCC 7 arithmetic processing data does not make sense and need not be added.

  The transmission of the null data 12 on the final 548th transmission line is for the same reason as in the first embodiment. In order to simplify the synchronous reproduction processing of the video signal 11 and the audio signals 9 and 10, the master clock frequency for transmission processing satisfies the condition of an integral multiple of the sampling frequency of the audio signals 9 and 10, and the video signal effective transmission line This is an extra data transmission amount generated when the frequency is calculated from the greatest common divisor satisfying the number. For this reason, since this transmission line is an invalid data area, after synchronous data (HDp) 4 and special data (HDs) 5 are serially transmitted, extra data transmission is padded with null data 12 and converted to 8B / 10B. Later, serial transmission is performed, and CRCC arithmetic processing data is not added.

  As with the first embodiment, the audio signal format to be transmitted is 3ch (L / R / Center) without changing the transmission format by setting the sampling plate number to 48 kHz and the level resolution to 16 bits. It is also possible to transmit a signal.

  As described above, according to the present embodiment, although a transmission section in which padding processing is performed with extra null data 14 and 15 occurs, transmission of unnecessary signals is not performed as much as possible by stopping transmission in the synchronous blanking section. By adding the audio signal superimposition processing section to the pixel data transmission only in the effective line section of the video signal 11, the 1080i component video (4: 2: 2) quality class uncompressed baseband digital HD video transmission is reduced. Optical transmission is possible at 1.27 Gbps.

  The present invention is not limited to the above embodiment. For example, in FIG. 2, the optical transmission module 2D and the optical reception module 31 are replaced with an optical fiber transmission / reception driver / receiver, thereby transmitting an optical fiber. It is also possible to do. Also, by adding special data 5 defined in advance after the synchronization data (HDp) 4, it is possible to obtain a key information switching signal such as scramble processing of transmission data applied for copyright protection, for example. Is possible.

<Third Embodiment>
By the way, in the formats 1 and 13 shown in FIGS. 1 and 3, respectively, the video signal 11 and the audio signals 9 and 10 are most of the transmission band. Therefore, the transmission band is widened to add new information for transmission. There is a need. Therefore, a third embodiment in which new information is added and transmitted without expanding the transmission band will be described. As shown in FIG. 5A, special codes A and C are used as synchronization data 2 and 4 representing the vertical synchronization signal Vsync and horizontal synchronization signal Hsync of the video signal 11 in the formats 1 and 13 shown in FIGS. 1 and 3, respectively. As the special codes A and C, for example, the IEEE 820.3 standard K character or comma character is used.

  The third embodiment is configured to represent the vertical synchronization signal Vsync and the horizontal synchronization signal Hsync (or either one). For example, as shown in FIG. 5B, two special codes A and B are allocated to represent the vertical synchronization signal Vsync, and each special code is defined to represent 1-bit data = 0 and 1, and the horizontal synchronization signal Hsync is defined. In order to express the two special codes C and D, each special code is defined to represent 1-bit data = 0, 1, so that new information is serial data (for example, RS232C) without expanding the transmission band. Can be transmitted. Further, if four special codes are assigned to one synchronization signal, transmission can be performed with 2-bit data = 00, 01, 10, 11 added without increasing the transmission band. Similarly, for the even field, odd field identification special data (HF) 3 and auxiliary synchronization data special data (HDs) 5, a plurality of different special codes are allocated so that each special code represents bit data. be able to.

  The present invention provides an optical wireless transmission means for combining an uncompressed baseband digital HD (High-Definition) video signal and a digital audio signal, a video signal format and a digital auxiliary control signal in an audio signal format and multiplexing them, or Serial transmission using optical signal transmission cable means, and after receiving the optical signal, the video signal, audio signal and auxiliary control signal are separated, and the video signal and audio signal can be reproduced respectively. It can be used for an optical wireless transmission device or an optical signal cable transmission device.

It is a schematic block diagram which shows the transmission format in the 1st Embodiment of this invention. It is a schematic block diagram of 1st Embodiment of the transmission system of this invention. It is a schematic block diagram which shows the transmission format in the 2nd Embodiment of this invention. It is a schematic block diagram which shows the data transmission format of an example of the conventional transmission system. It is explanatory drawing which shows the special code | symbol showing the synchronous data in the 3rd Embodiment of this invention.

Explanation of symbols

1 Signal format of 1366 pixels x 768p video 2 Vertical synchronization identification synchronization data (HV)
3 Special data for identifying even and odd fields (HF)
4 Sync data for valid line identification (HDp)
5 Special data for auxiliary synchronization data (HDs)
6, 8 Auxiliary control data (CTL1, CTL2)
7 CRCC for data transmission error detection
9 1/2 field of the first half of the audio signal transmission block 10 1/2 field of the second half of the audio signal transmission block 11 Effective data transmission area of the video signal 12 Padding processing null data transmission area 13 1920 pixels × 1080i video signal format 14 Audio signal Transmission block padding processing transmission area (null data)
15 Padding processing transmission area of audio signal transmission block (null data)
16 Padding processing area common to audio signal and video signal 17 Digital video signal input terminal 18 Digital audio signal input terminal 20 Optical transmission processing block 21, 3A Video memory 22, 39 Video memory write / read control unit 23 Audio signal clock oscillator 24 3D audio memory (FIFO)
25 Error correction code generation processing unit 26 Video / audio control auxiliary data processing unit 27 Master clock oscillator for transmission processing 28 Video / audio synthesis unit 29 Transmission timing generation circuit 2A Special data addition control unit 2B 8 bits / 10 bits (8B / 10B ) Conversion unit 2C Parallel / serial conversion unit 2D, 31 Optical transmission module 2E CRCC generator 30 Optical reception processing block 32 Serial / parallel conversion unit 33 10-bit / 8-bit (10B / 8B) conversion unit 34 Special data monitoring control unit 35 Reception timing generation circuit 36 Video / audio separation unit 37 Self clock oscillator 38 Audio signal reproduction clock oscillator 3B Rescaling video timing generation circuit 3C Video / audio control auxiliary data monitoring unit 3E Error correction processing unit 41 Optical wireless transmission line 42 Digital video signal Power terminal 43 the digital audio signal output terminal

Claims (9)

A transmission system that performs serial transmission by multiplexing digital auxiliary signals containing auxiliary information about video formats, audio formats, etc. together with digital video signals and digital audio signals at an uncompressed baseband level,
First storage means for storing pixel data of the digital video signal for each predetermined unit section;
Second storage means for storing the digital audio signal in units of audio samples with a sampling frequency synchronized with a master clock oscillator for transmission processing in units of predetermined units;
Third storage means for storing the digital auxiliary signal;
First synchronization data defined as vertical synchronization signal synchronization data for the digital video signal; second synchronization data defined as effective line identification synchronization data for the digital video signal; and the first storage means. A plurality of lines obtained by synthesizing the digital video signal read from the second storage means, the digital audio signal read from the second storage means, and the digital auxiliary signal read from the third storage means in time series in a predetermined order. Transmission signal generating means for generating a transmission signal comprising:
Output means for serially transmitting and outputting the transmission signal output from the transmission signal generating means;
The transmission signal generation means reads the digital auxiliary signal from the third storage means, following the first synchronization data, by reading out a predetermined number of bits and synthesizing the signal in a time-series manner. Then, following the second synchronization data, a signal obtained by reading out the digital auxiliary signal from the third storage means by a predetermined number of bits and synthesizing in a time series is used as a transmission signal of the second line, and the third line Thereafter, the transmission signal of each of the plurality of lines up to a predetermined line is the sample data amount M (M: M: M) of the digital audio signal that needs to be transmitted per field from the second storage means following the second synchronization data. The data section L (L: natural number) obtained by dividing the natural number) byte by the effective line number N (N: natural number) of the digital video signal is sequentially read out, and then is read from the first storage means. Transmission system chronologically synthesized, characterized in that the signals which eliminated the blanking signal sequentially reads the valid pixel data component in each line of the digital video signal. The digital video signal is a video signal to be displayed by a progressive scanning method,
The digital audio signal in a plurality of lines from the third line of the transmission signal to the predetermined line is obtained by dividing the sample data amount obtained by adding an error correction code to the digital audio signal that needs to be transmitted per field in two. 2. The transmission system according to claim 1, wherein the data sections L obtained by dividing the sampled data amount by 1/2 of the number of effective lines are sequentially transmitted. The digital video signal is a video signal to be displayed by an interlace scanning method,
The digital audio signal in a plurality of lines from the third line to the predetermined line of the transmission signal is divided into two by dividing a sample data amount obtained by adding an error correction code to the digital audio signal that needs to be transmitted per field. The first half data section and the second half data section obtained by dividing the obtained sample data amount by 1/2 of the number of effective lines are combined and transmitted on each line. 1. The transmission system according to 1.   The transmission signal generation means adds the special data for identifying whether the field is an even field or an odd field in time series following the first synchronization data, and then transmits the transmission signal of the first line to which the digital auxiliary signal is added. After the second synchronization signal, the special data that is the third auxiliary synchronization data is added in time series, and then the digital auxiliary signal or the digital audio signal and the digital video signal are added. The transmission system according to claim 1, wherein transmission signals from the second line are generated.   The transmission signal generating means generates a null data amount corresponding to a sample data amount of the digital audio signal that needs to be transmitted per field and a read data amount of effective pixel data in the plurality of lines of the digital video signal. The transmission system according to claim 1, wherein the padding process is performed by the transmitter.   The transmission signal generating means satisfies a condition of an integral multiple of the sampling frequency of the digital audio signal, and a frequency calculated from the greatest common divisor satisfying the number of effective transmission lines of the digital video signal as a master clock frequency, The transmission system according to claim 1, wherein the transmission signal is generated.   7. The output unit according to claim 1, wherein the transmission signal output from the transmission signal generation unit is subjected to 8-bit / 10-bit parallel conversion, parallel / serial conversion, and serial transmission output. The transmission system according to any one of the above.   8. A plurality of special codes are assigned to at least one of the first and second synchronization data, and each special code represents bit data indicating information. Transmission system. A plurality of special codes are allocated to at least one of special data for identifying whether the field is an even field or an odd field and special data which is third auxiliary synchronization data, and each special code represents bit data indicating information. The transmission system according to any one of claims 4, 7, and 8.

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