JP4962024B2 - Data transmission / reception system - Google Patents

Description

  The present invention relates to a data transmission / reception system using a digital interface in which video, audio, data, etc. are multiplexed, such as HDMI (High-Definition Multimedia Interface), and in particular, the HDMI is improved and the receiving side is a clock master. To achieve high sound quality by utilizing the clock purity.

  In recent years, HDMI has become widespread. This is because a single video / audio / additional data can be transmitted. This has made it easier and more convenient to connect digital devices. However, on the other hand, since it is not a pure audio device, a severe evaluation that sound quality is not good from some audiophiles who are eager for high sound quality has come to be seen. In practice, there are many problems that are due to insufficient mounting noise countermeasures, which is a problem specific to equipment, but there is still room for improvement in terms of achieving the ultimate as a system. it is conceivable that.

  The feature of HDMI is that if a video signal and an audio signal are coherently synchronized on a clock basis on the transmission side, the state can be transmitted to the reception side as it is and projected. Specifically, it has a mechanism for reproducing a coherent audio clock by transmitting a video clock (pixel clock) and additional data. Various video clocks and audio clocks are prepared so that they can be selected. In addition, transmission parameters corresponding to all combinations thereof are prepared (for example, see Patent Document 1 and Non-Patent Document 1).

  FIG. 7 is a diagram illustrating an example of a conventional data transmission / reception system using HDMI. In the figure, 10 is a transmission side device, 20 is a reception side device, and 15 is an HDMI cable. The transmission side device 10 includes a transmission side pixel clock generation unit 900, a transmission side audio clock generation unit 850, a CTS generation unit 100, a BD / DVD decoder 951 that reproduces the BD 950 and extracts a video signal and an audio signal. , An HDMI data encoder 952 that encodes the output of the BD / DVD decoder 951 and outputs the HDMI data D, and a control means 610 that controls the overall operation of the transmission-side device. The CTS generation unit 100 includes a 1 / N frequency divider 110 that divides the audio clock 85 by a value N given from the control unit 610, and a counter 120 that counts the output of the 1 / N frequency divider 110 with the pixel clock 90. Is provided. The receiving side device 20 also includes an audio clock reproduction unit 200, an AV data decoding unit 700, a DA converter 680, and a control unit 620 that controls the overall operation of the receiving side device. The audio clock reproduction means 200 includes a frequency divider 210 that divides the pixel clock (PCK) received from the transmission-side device 10 by the CTS signal received from the transmission-side device 10, a phase comparator (PD) 220, and a voltage-controlled oscillator. (VCO) 230 and a PLL configured with a 1 / N frequency divider 240.

The operation of the conventional data transmission / reception system configured as described above will be described.
In the transmission side device 10, the pixel clock 90 generated by the transmission side pixel clock generation unit 900 is supplied to the CTS generation unit 100 and transmitted to the reception side device 20 via the HDMI cable 15 as PCK 1. In the CTS generation unit 100, the audio clock 85 generated by the transmission side audio clock generation unit 850 is frequency-divided by the 1 / N frequency divider 110 to a frequency of 1 / N. Here, the parameter N of the 1 / N frequency divider 110 is given from the control means 610. The counter 120 counts the period of the frequency 128 Fs / N, which is the frequency-divided output of the 1 / N frequency divider 110, with the pixel clock PCK90. The output of the counter 120 is transmitted as CTS 1 to the receiving side device 20 via the HDMI cable 15. The parameter N is transmitted as N1 to the receiving side device 20 via the HDMI cable 15. Also, the BD / DVD decoder 951 reproduces the BD 950 to extract the video signal and the audio signal, and the HDMI data encoder 952 encodes the output of the BD / DVD decoder 951 and outputs the HDMI data D. This data D is transmitted as Data 1 to the receiving side device 20 via the HDMI cable 15.

  In the receiving device 20, the audio clock 82 is reproduced by the audio clock reproduction means 200 based on PCK 1, CTS 1, N 1 and Data 1 received via the HDMI-1 cable 15. That is, the frequency divider 210 divides PCK1 by CTS1. The frequency that becomes the PCK / CTS is multiplied by N times by a PLL that includes a phase comparator (PD) 220, a voltage controlled oscillator (VCO) 230, and a 1 / N frequency divider 240. As a result, the 128 Fs audio clock 82 is reproduced. The data is decoded by AV data decoding means 700 and taken out as audio data 70 and video data 71. The audio data 70 is supplied to the DA converter 680 and DA-converted at the timing of the audio clock 82 reproduced by the audio clock reproduction means 200.

There are two major factors that cause deterioration in sound quality in such HDMI.
First, since only the video clock (pixel clock) is transmitted and becomes a reference, if the clock purity is low, the audio clock purity is similarly lowered.

  Second is the effect of the regenerative PLL. FIG. 8 illustrates various clock spectra.

  FIG. 8A shows the spectrum of the crystal oscillation output. In this spectrum, it can be seen that the clock purity is sufficiently high with little sideband noise and minimal frequency drift.

  FIG. 5B is an example of a spectrum when a coherent clock created using HDMI is reproduced on the receiving side using PLL. In this example, the clock is slightly jittery due to the influence of the VCO constituting the PLL.

  For reference, FIG. 2C shows an example in which the influence of the system jitter inherent in the case of transmitting the clock using IEEE 1394 is present due to the asynchronous clock.

  For high sound quality, it is necessary to operate a high-precision DA converter with a clock having high clock purity. Time axis fluctuations and inaccuracies (jitter) are converted to voltage by the DA converter, and the signal is distorted and noise increases. For example, a clock such as the one shown in FIG. I can't hope. For this high sound quality, it is better that the clock purity is as shown in FIG.

  In order to solve both of these, it is preferable to place a crystal oscillation means on the receiving side and supply a high-purity clock without jitter directly to the DA converter.

  However, in order to place the crystal oscillation means on the receiving side, it is necessary to adjust the data rate to the receiving master in a long cycle. Otherwise, data deficiency will occur.

  For this purpose, there is a conventional technique in which the frequency deviation information is returned from the receiving side to the transmitting side, and the asynchronous packet data is sent finely or loosely so as to match it (see, for example, Patent Document 2).

Next, the case where this prior art is solved in combination with HDMI will be described.
In order to directly supply a DA converter with a high-purity clock without jitter by placing a crystal oscillation means on the reception side, a conventional data transmission / reception system 9000 comprising a crystal transmission means on the reception side using HDMI is used. An example is shown in FIG.

In FIG. 9, 10 is a transmission side device, 20 is a reception side device, and 15 is an HDMI cable.
In FIG. 9, reference numeral 100 denotes a part of the HDMI audio clock reproduction system, but here, data obtained by counting 128 times the audio clock period by the pixel clock PCK1 is transmitted as CTS1 by HDMI together with the N parameter. . Similarly, 200 is a part of an HDMI audio clock reproduction system. With the PLL configuration, the same frequency 82 as the 128-times audio clock on the transmission side is reproduced. Normally, this HDMI audio clock reproduction system is used.

  Reference numeral 800 denotes crystal oscillation means. The output 80 of the crystal oscillation means 800 can be used as a high-purity audio clock in the high sound quality mode. However, when the receiving side is set as a master, it is independent of the clock on the transmitting side, so that a frequency difference inevitably occurs. This frequency difference causes an excess or deficiency of data with time. Here, even if there is an excess or deficiency of data, it is necessary to keep the amount of data within a certain range of the buffer capacity. Therefore, ARC_CONT is fed back to the transmitting-side device 10 via CEC1 under the control of the control unit 620 that manages the data flow in the buffer 690. Based on this, the control means 610 switches the three crystal oscillation means on the transmission side. Of these, 850 is the center frequency, 860 is the center + 0.1% deviation, and 870 is the center -0.1% deviation. The concept of control is shown in FIG.

  In FIG. 2A, first, a higher crystal is used so that the buffer size becomes the center. Thereafter, the center frequency is restored. Even at the center frequency, there is a slight frequency difference, so that the buffer storage size is a predetermined ref1. In this case, the crystal on the + side is selected so as to avoid underflow. Then, the storage size of the buffer reaches a predetermined ref2, and this time, the buffer is returned to the center frequency in order to avoid overflow. This is repeated thereafter. In this way, the buffer is managed and the data rate matches the rate of the receiving crystal as an average value. FIG. 5B shows the case where the transmission / reception center frequency shift is opposite, but a detailed description is omitted for simplicity. Returning to FIG. 9, these operations will be described. In this way, data rate flow control at the receiving crystal can be achieved.

  However, this system has challenges. In other words, since the clock frequency on the transmission side is greatly varied, not only on the reception side but also on the transmission side, the sound clock fluctuates greatly and the pitch always shifts to either high or low when reproducing the sound simultaneously. is there. Such pitch and pitch deviations are unacceptable for Hi-Fi enthusiasts.

  Another problem is the difference between the audio clock and the video clock. The sound is rate-controlled on the receiving side, while the video is rate-controlled on the transmitting side, so the time difference between the image and the sound increases with time.

  FIG. 11 is a graph showing this situation. The relative frequency deviations are ± 30 ppm and ± 100 ppm. It can be seen that at +100 ppm, a time difference of +100 ms occurs within 30 minutes. In the case of lip sync experienced in movies and the like, there is an investigation that when the sound is delayed from the picture, it feels strange about +100 ms (see FIG. 12).

On the other hand, when the sound advances from the image, the detection limit becomes -20 ms, which becomes even stricter. Therefore, the fact that the video clock and the audio clock are asynchronous becomes a big problem in AV contents.
Japanese Patent Laid-Open No. 2004-23187 JP 2002-57636 A HDMI (High-Definition Multimedia Interface) Specification V1.3

  In order to give the highest priority to the playback sound quality on the receiving side, when the crystal oscillation means is placed on the receiving side, when the method using data flow control is used, the clock fluctuation on the transmitting side is large, and the sound quality on the transmitting side is There is a problem of sacrificing, and there is a problem that lip sync is shifted due to a frequency deviation between the video clock and the audio clock.

  The present invention has been made in view of the above-described conventional problems. Data transmission / transmission that can secure sound quality not only on the reception side but also on the transmission side, and can also solve the problem of lip sync. It aims to provide a receiving system.

  In order to solve the above problems, a data transmission / reception system according to the present invention transmits video data 1, audio data 1, additional data 1, and video clock 1 from a first device to a second device. And a second mode for transmitting the video clock 2 from the second device to the first device, and having a basic mode for transmitting the video clock 1 generated by the first device to the second device. And a second mode for transmitting the video clock 2 generated by the second device to the first device. In the second mode, the first device has the second mode The video clock 2 generated by the device and transmitted to the first device is used to adjust the data rate of either the video data 1 or the audio data 1 sent from the first device or one of them. is there.

  As a result, the data rate of video and audio data transmitted from the transmission side can be adjusted on a clock basis without causing large fluctuations in the clock on the transmission side, thereby ensuring sound quality on the transmission side. The problem of lip sync due to frequency deviation between the video clock and the audio clock can also be suppressed.

  The data transmission / reception system according to the present invention includes transmission means for transmitting the video data 1, the audio data 1, the additional data 1, and the video clock 1 from the first device to the second device. A basic mode for transmitting the video clock 1 generated by the second device to the second device, and transmission means for transmitting the additional data 2 and the video clock 2 from the second device to the first device. The second device further has a second mode for transmitting the video clock 2 from the second device to the first device, and the second device receives the video clock 1 transmitted from the first device in the second mode. The video clock 2 is transmitted to the first device as it is, and the first device uses the additional data 2 transmitted from the second device to reproduce the audio clock, and the sound clock PLL. A video clock PLL for reproducing a video clock based on an audio clock reproduced by the clock PLL is provided, and in the second mode, the inside of the first device is operated by the video clock reproduced by the video clock PLL. It is something to be made.

  As a result, the data rate of video and audio data transmitted from the transmission side can be adjusted on a clock basis without causing large fluctuations in the clock on the transmission side, thereby ensuring sound quality on the transmission side. The problem of lip sync due to frequency deviation between the video clock and the audio clock can also be suppressed.

  The data transmission / reception system according to the present invention includes transmission means for transmitting the video data 1, the audio data 1, the additional data 1, and the video clock 1 from the first device to the second device. A basic mode for transmitting the video clock 1 generated by the second device to the second device, and a transmission means for transmitting the additional data 2 from the second device to the first device. A second mode for transmitting the additional data 2 to be transmitted to the first device, wherein the second device uses the audio clock generated by the second device in the second mode, and Audio data is converted to analog by the DA converter provided in the second device, and the audio clock generated by the second device is divided by the same predetermined frequency division ratio N used in the basic mode. The cycle The data counted by the clock 1 is transmitted as the additional data 2, and the first device reproduces the audio clock by using the additional data 2 transmitted from the second device, and the audio clock PLL. A video clock PLL for reproducing a video clock based on an audio clock reproduced by the clock PLL is provided, and in the second mode, the inside of the first device is operated by the video clock reproduced by the video clock PLL. In addition, the additional data 2 may be obtained by further multiplying the audio clock generated by the second device by M times the same predetermined frequency division ratio N as that used in the basic mode (M is an integer of 2 or more). ) Is divided into longer periods.

  As a result, the data rate of video and audio data sent from the transmission side can be adjusted on a clock basis without causing large fluctuations in the clock on the transmission side, while taking a configuration that obtains extremely high sound quality on the reception side. As a result, the sound quality on the transmission side can be ensured, the problem of lip sync due to the frequency deviation between the video clock and the audio clock can be suppressed, and the number of HDMI cables connecting the transmission side and the reception side can be reduced to one. can do.

  Moreover, it is preferable that a DA converter for converting audio data into analog is provided on the receiving side on the receiving side where the crystal oscillation means is placed.

  In addition, since the video clock is reproduced by the phase-locked loop based on the audio clock, the AV lip sync problem can be solved.

  Also, inquiries about whether or not the above-mentioned special configuration can be taken between devices, and the operation is performed only when the device has the function, thereby avoiding problems associated with lack of mutual compatibility. Can do.

  Also, depending on the system, content that cannot be rate-controlled may be handled, and in such a case, the configuration can be prevented by using the conventional mode.

  As described above, according to the present invention, the video clock 2 is generated on the reception side and transmitted to the transmission side, and both video data and audio data sent from the transmission side using the video clock 2 are transmitted on the transmission side. Or any one of the data rates is adjusted so that the data rate of video and audio data sent from the transmission side can be adjusted on a clock basis without causing a large fluctuation in the clock on the transmission side. Thus, the sound quality on the transmission side can be ensured, and the problem of lip sync due to the frequency deviation between the video clock and the audio clock can also be suppressed.

  According to the present invention, the receiving side transmits the video clock 2 and the additional data 2 to the transmitting side, and the transmitting side reproduces the audio clock using the additional data 2 transmitted from the receiving side, Since the video clock PLL for reproducing the video clock based on the audio clock reproduced by the audio clock PLL is provided, and the transmission side is operated by the video clock reproduced by the video clock PLL. The data rate of the video and audio data sent from the transmission side can be adjusted on a clock basis, so that the sound quality on the transmission side can be secured, and the problem of lip sync caused by the frequency deviation between the video clock and the audio clock is eliminated. Can also be suppressed.

  According to the present invention, the receiving side includes crystal oscillation means for generating an audio clock, converts audio data to analog using the audio clock generated by the crystal oscillation means, and converts the audio clock to a predetermined amount. Data obtained by counting the frequency divided by the frequency ratio with the video clock 1 is transmitted as additional data 2 to the transmission side, and the transmission side reproduces the audio clock using the additional data 2 transmitted from the reception side. A configuration comprising a clock PLL and a video clock PLL for reproducing a video clock based on the audio clock reproduced by the audio clock PLL, and operating the transmission side with the video clock reproduced by the video clock PLL As a result, extremely high sound quality can be obtained on the receiving side, and the data rate of video and audio data sent from the transmitting side can be It can be adjusted on the basis of this, so that the sound quality on the transmission side can be secured, the problem of lip sync due to the frequency deviation between the video clock and the audio clock can be suppressed, and the transmission side and the reception side can be further controlled. The number of HDMI cables to be connected can be one.

The best mode for carrying out the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 shows a configuration of a data transmission / reception system 1000 according to Embodiment 1 of the present invention.
In FIG. 1, a transmission-side device 10 is a DVD / BD (Blu-ray Disc) player / recorder, an HDD built-in television broadcast receiver, a personal computer with a television broadcast reception function, an HDD recorder, or the like. The receiving side device 20 is an AV receiver amplifier, an AV theater system, a digital television, or the like. In addition, data or the like is transmitted from the transmission-side device 10 to the reception-side device 20 via the HDMI-1 cable 15. Further, the HDMI-2 cable 35 transmits additional data, a clock, and the like in the reverse direction.

  The transmission side device 10 has a function of reproducing the BD 950 to extract a video signal and an audio signal, and a monitor function (not shown) for reproducing the video signal and the audio signal relatively easily.

  In addition, basically, means 100 for generating clock parameters N and CTS is provided as part of the HDMI transmission unit. Further, it has functions of a control unit 610 for controlling the whole, a pixel clock selection unit 631, and an audio clock selection unit 633 in accordance with the internal operation state and mode. At the same time, as a partial function of the HDMI receiving unit, means 400 for reproducing the audio clock 2 from the second N and CTS parameters is provided as an extended function.

  The receiving-side device 20 is an amplifier for a theater system, and basically, as part of the HDMI-1 receiving unit, an audio clock reproducing means 200, an AV data decoding means 700, and a DA converter 680 for reproducing an audio signal. Is provided. Further, it has functions of a control means 620 for controlling the whole and an audio clock selection means 640 corresponding to the internal operation state and mode. At the same time, the receiving side independent crystal oscillator for audio clock 800, the PLL 500 for generating the pixel clock from the audio clock, and the means 300 for generating the transmission parameters N2 and CTS2 are provided as extended functions.

Next, the operation of the data transmission / reception system 1000 according to the first embodiment will be described with reference to FIG.
First, the basic mode among the operation modes of this system will be described.
This basic mode is the same as the conventional operation mode, and in the initial state, the connection partner, that is, the data transmission device 10 and the data reception device 20 can both perform the operation of the first embodiment of the present invention. This is used when it is not known whether or not.

  In the conventional operation mode, the transmission side device 10 becomes all the clock masters. In PC content and the like, A (audio) and V (video) may be asynchronous, but in general AV content, A and V are synchronized, and an audio clock and a video clock However, it is often coherent. In this case, although the transmission side pixel clock generation unit 900 and the transmission side audio clock generation unit 850 are drawn separately in the drawing, they are actually coherent states in which the synchronization relationship is maintained and are mutually dependent. It is in.

  The control unit 610 supplies the selection instruction data SL11 to the pixel clock selection unit 631. Thus, the pixel clock selection unit 631 outputs the output 90 of the transmission side pixel clock generation unit 900 as the clock 92. The clock 92 is supplied to the means 100 for generating N and CTS, and is transmitted as PCK1 to the receiving-side device 20 via the HDMI-1 cable 15. In the N, CTS generation means 100, N supplied from the control means 610 is given, and the frequency divider 110 divides the audio clock 83 to 1 / N frequency. The counter 120 counts the period of the frequency 128 Fs / N with the clock 92, that is, PCK, and outputs it as CTS1.

  Further, the control unit 610 provides the selection instruction data SL12 to the audio clock selection unit 633, whereby the audio clock selection unit 633 outputs the output 85 of the transmission side audio clock generation unit 850 as the clock 83. This clock 83 is supplied to the N, CTS generator 100. In synchronization with these clocks, AV content data is transmitted to the receiving-side device 20 through Data 1 of the HDMI-1 cable 15. N and CTS generated by the N and CTS generation means 100 are constants in the case of AV coherent, and are transmitted to the receiving side device 20 as N1 and CTS1 through the HDMI-1 cable 15.

  In one receiving side device 20, the audio clock 82 is reproduced by the audio clock reproducing means 200 based on PCK 1, CTS 1, N 1, and Data 1 received via the HDMI-1 cable 15. Details are as follows.

  That is, the frequency divider 210 divides PCK1 by CTS1. The frequency which becomes this PCK / CTS is multiplied N times by PLL. The PLL has a loop configuration including a phase comparison circuit 220, a voltage controlled oscillator 230, and a local frequency divider 240. As a result, the 128 Fs audio clock 82 is reproduced.

  The data is decoded by AV data decoding means 700 and taken out as audio data 70 and video data 71. The audio data 70 is supplied to the DA converter 680. The audio clock selection unit 640 selects the audio clock 82 based on the control signal SL2 of the control unit 620 and supplies the clock to the DA converter 680.

  As described above, in the basic operation mode, which is the conventional mode, the audio clock of the DA converter 680 is the output of the audio clock reproduction means 200 generated by the PLL, which is transmitted through the pixel clock PCK1, The transmission side audio clock generation means 850 in FIG. As described above, the purity of the clock generated by the PLL is not so high, and the purity is further lowered when another clock is mediated.

  In addition to the basic operation mode, which is the conventional mode described above, the system according to the first embodiment has a second mode. Next, the operation in the second mode will be described.

  In the second mode, the receiving side device 20 becomes the audio clock master. That is, a clock system is formed based on the crystal audio clock 80 of the crystal oscillation means 800.

  In the receiving device 20, the clock 80 is supplied to the PLL 500 that generates the pixel clock from the audio clock, and the pixel clock 91 that is synchronized with the crystal audio clock 80, that is, coherent with the crystal audio clock 80, is generated. Details are as follows.

  That is, the crystal audio clock 80 is frequency-divided by 1 / N by the frequency divider 510, and is composed of a voltage control oscillator 530, a local frequency divider 540, and a phase comparison circuit 520, and includes a video mode and an audio sampling frequency mode. Corresponding to the frequency, the frequency is multiplied by the frequency of Nominal CTS, which is a predetermined CTS value defined by the HDMI standard. This Nominal CTS is supplied from the control means 620. Thus, the frequency of the clock is CTS / N times that of the crystal audio clock 80, and becomes the pixel clock 91 (= PCK2).

  Next, the crystal sound clock 80 and the pixel clock 91 are input to the means 300 for generating the transmission parameters N2 and CTS2, and the transmission parameters N2 and CTS2 are generated. The means 300 for generating the transmission parameters N2 and CTS2 has the same configuration as that of the means 100 for generating N and CTS described above, and the operation is also the same.

  Through the HDMI-2 cable 35, the pixel clock 91 is transmitted to the transmission side device 10 as PCK2 together with CTS2 and N2.

  The transmitting-side device 10 receives the clock and parameters from the HDMI-2 cable 35 and reproduces the audio clock 81 by means 400 for reproducing the audio clock 2 from the second N, CTS parameters N2 and CTS2. To do. Under the control of the control means 610, the SL 12 is supplied to the audio clock selection means 633, and the audio clock 81 is selected and output as the clock 83. The means 400 for reproducing the audio clock 2 from the second N, CTS parameter is reverse in the direction of the drawing, but is the same as the configuration of the audio clock reproducing means 200 and the operation is also the same. Omitted.

  On the other hand, PCK2 supplied from the HDMI-2 cable 35 to the transmission-side device 10 is selected by the pixel clock selection unit 631 under the control of the control unit 610 and output as the clock 92. The transmission side device 10 operates as a whole in synchronism with these two clocks. That is, data reading from BD, AV monitor output from decoding, and the like. Of course, the output to the HDMI-1 cable 15 is also based on these two clocks. That is, this is supplied to the means 100 for generating N and CTS, and at the same time, the clock 92 is output as PCK1.

  In one receiving-side apparatus 20, the audio clock 82 is reproduced by the audio clock reproduction means 200 based on PCK 1, CTS 1, N 1, and Data 1 received via the HDMI-1 cable 15. The audio clock 82 is once transmitted to the transmitting device 10 with reference to the crystal audio clock 80 as a source, and then returned to the receiving device 20 again. Although it seems to be meaningless at first glance, it is not so. In each part of the circuit, data reproduction is performed in the transmission side device 10 synchronized with the respective clocks, and the data transmission of the HDMI-1 cable 15 is determined and operated in synchronization with the data transmission. There is. However, since the spectrum purity of the clock 82 itself that has made a round is lowered, it is not suitable for the clock of the DA converter 680, and the original high-purity crystal audio clock 80 is used. That is, the control unit SL 620 controls the audio clock selection unit 640 to supply the output clock 80 of the crystal oscillation unit 800 as the audio clock of the DA converter 680.

  As is apparent from the above description, in the second mode, the receiving side device 20 becomes the audio clock master, and the entire system including the transmitting side device 10 can be completely AV-synchronized.

  With the above configuration, while taking a configuration that obtains extremely high sound quality on the receiving side, there is no clock fluctuation on the transmitting side and no frequency deviation from the video clock, so not only the receiving side but also the sound quality on the transmitting side Can be obtained, and a specific effect that the problem of lip sync does not occur can be obtained.

Next, the operation of the system according to the first embodiment will be described with reference to the general operation flow shown in FIG.
First, a sequence for transitioning from the basic operation mode to the second mode, which is a feature of the first embodiment of the present invention, will be described.
In FIG. 2, the operation of the transmission side device 10 is shown in the left dotted line, and the operation state of the reception side device 20 is shown in the right dotted line.

  First, the transmission-side device 10 inquires of the reception-side device 20 about “possibility” of the second mode (S101).

  The receiving side device 20 answers “Yes” to this (S201).

  When it is a reply that it has the function of the second mode, the transmission side device 10 changes the internal operation mode to the second mode, and simultaneously generates a pixel clock from the audio clock in the reception side device 20. Queries the stability / unstableness of the output of the PLL 500 (ie, PCK2 = clock 91).

  The receiving side device 20 self-determines whether the output of the PLL 500 is stable or not and responds to this (S203).

  Next, the transmission side device 10 self-determines whether the output of the means 400 for reproducing the audio clock 2 (audio clock 2 = clock 81) is stable or unstable from the second N and CTS parameters (S104).

  If OK, the audio clock selection means 633 and the pixel clock selection means 631 are controlled by the control means 610, and the audio clock 2 is reproduced from the second N, CTS parameters as the audio clock and the pixel clock 400. And PCK2 are selected (S105, S106).

  The transmission side device 10 reports to the reception side device 20 that it has completely shifted to the second mode (S107).

  In response to this, the receiving side device 20 controls the audio clock selection unit 640 with the control signal SL2 of the control unit 620, and supplies the output clock 80 of the crystal oscillation unit 800 as the audio clock of the DA converter 680 (S208). ).

  Finally, the receiving side device 20 reports to the transmitting side device 10 that the transition to the second mode has been completed (S209).

  Upon receiving this, the transmission side device 10 completes the transition sequence to the second mode (S110).

  In this way, by inquiring whether or not a special configuration in the second mode can be taken between the devices, it is possible to perform the operation only when the device has the function. Problems associated with incompatibility can be prevented.

  Also, depending on the system, content that cannot be rate controlled, such as broadcast reception and repeat transmission of external input signals, may also be handled. In this case, the basic operation mode, which is the conventional mode, is used. By doing so, it is possible to prevent problems such as data flow over / under.

  The data transmission / reception system of the first embodiment as described above includes transmission means for transmitting the video data 1, the audio data 1, the additional data 1, and the video clock 1 from the transmission side device to the reception side device. In addition, a transmission means for transmitting the additional data 2 and the video clock 2 from the receiving device to the transmitting device is further provided, and the video clock 2 generated by the second device and transmitted to the first device is used. Since the data rate of the video data 1 and / or the audio data 1 sent from the transmission side device is adjusted, the crystal oscillation means for generating the audio clock is provided on the reception side. By transmitting the video clock 2 to be transmitted and the additional data 2 to the transmitting side, in addition to the conventional mode, the receiving side is configured to obtain extremely high sound quality while the transmitting side clock The data rate of video and audio data sent from the transmission side can be adjusted on a clock basis without causing any significant fluctuations, thereby ensuring the sound quality of the transmission side. A system that can suppress the problem of lip sync due to frequency deviation can be obtained.

(Embodiment 2)
FIG. 3 shows a configuration of a data transmission / data reception system according to the second embodiment of the present invention.
In FIG. 3, the same means as in FIG.
In the second embodiment, the configuration in which the crystal oscillation means 800 is placed in the receiving-side device 20 and a high-purity clock is directly supplied to the DA converter 680 is the same as in the first embodiment. In the second embodiment, the function of generating the pixel clock with reference to the crystal audio clock 80 is moved to the transmitting device 10 side.

Next, the operation of the data transmission / reception system 1000 of the second embodiment will be described with reference to FIG.
The operation in the basic mode is the same as that in the first embodiment, and the operation in the second mode will be described below.
In the receiving-side device 20, a clock system is formed with reference to the crystal audio clock 80 of the crystal oscillation means 800. In the receiving side device 20, the clock 80 is supplied to the means 300 for generating the transmission parameters N <b> 2 and CTS <b> 2, the parameters are generated, and transmitted to the transmitting side device 10 via the HDMI-2 cable 35. At this time, the PCK supplies the PCK1 received from the transmission side device 10. PCK2 supplied to the HDMI-2 cable 35 also returns PCK1.

  The transmitting-side device 10 receives the clock and parameters from the HDMI-2 cable 35 and reproduces the audio clock 81 by means 400 for reproducing the audio clock 2 from the second N and CTS parameters N2 and CTS2. . This audio clock 81 is synchronized with the audio clock 80. At this time, the frequency of the PCK is indefinite, but as long as it is common to the transmission side device 10 and the reception side device 20, there is no major problem, and the synchronization relationship between the audio clocks operates correctly. Under the control of the control means 610, the SL 12 is supplied to the audio clock selection means 633, and the audio clock 81 is selected and output as the clock 83.

  Next, the clock 83 is supplied from the audio clock on the transmission side device 10 side to the PLL 500 that generates the pixel clock. Thus, the pixel clock 91 that outputs the pixel clock 91 synchronized with the clock 83 is selected by the pixel clock selection unit 631 under the control of the control unit 610 and is output as the clock 92. The transmission-side device 10 operates as a whole in synchronization with these two clocks. That is, data reading from BD, AV monitor output from decoding, and the like. Of course, the output to the HDMI-1 cable 15 is also based on these two clocks. That is, this is supplied to the means 100 for generating N and CTS, and at the same time, the clock 92 is output as PCK1.

  In the receiving device 20, the audio clock 82 is reproduced by the audio clock reproducing means 200 based on PCK 1, CTS 1, N 1, and Data 1 received via the HDMI-1 cable 15. Since the clock 82 itself that has made a round has degraded spectrum purity, it is not suitable for the clock of the DA converter 680, and the original high-purity crystal audio clock 80 is used. That is, the control unit SL 620 controls the audio clock selection unit 640 to supply the output clock 80 of the crystal oscillation unit 800 as the audio clock of the DA converter 680.

  As is clear from the above description, also in the second embodiment, as in the first embodiment, in the second mode, the receiving side device 20 becomes the audio clock master, and the transmitting side device 10 is The system including the entire system can be completely AV-synchronized.

  In addition, while taking a configuration that obtains extremely high sound quality on the receiving side, there is no clock fluctuation on the transmitting side and no frequency deviation from the video clock, so not only on the receiving side but also on the transmitting side It is possible to obtain the specific effect of ensuring that there is no problem of lip sync.

Next, the operation of the system according to the second embodiment will be described with reference to the general operation flow shown in FIG.
In FIG. 4, the operation of the transmission side device 10 is shown in the left dotted line, and the operation state of the reception side device 20 is shown in the right dotted line.

  First, the transmission-side device 10 inquires of the reception-side device 20 about “possibility” of the second mode (S101).

  The receiving side device 20 answers “Yes” to this (S201).

  When it is a reply that it has the second mode function, the transmitting-side device 10 changes the internal operation mode to the second mode (S102).

  Next, the transmission side device 10 self-determines whether the output of the means 400 for reproducing the audio clock 2 (audio clock 2 = clock 81) is stable or unstable from the second N and CTS parameters (S103).

  If OK, the audio clock selection means 633 and the pixel clock selection means 631 are controlled by the control means 610, and the clock 81 is selected as the audio clock (S104).

  Next, whether the output of the PLL 500 that generates the pixel clock from the audio clock (that is, PCK2 = clock 91) is stable or unstable is determined (S105).

  If OK, the pixel clock selection means 631 is controlled by the control means 610, and the output of the means 400 for reproducing the audio clock 2 from the second N, CTS parameters, PCK2 (pixel clock 91), as the pixel clock, Select (S106).

  The transmission side device 10 reports to the reception side device 20 that it has completely shifted to the second mode (S107).

  In response to this, the receiving side device 20 controls the audio clock selection unit 640 with the control signal SL2 of the control unit 620, and supplies the output clock 80 of the crystal oscillation unit 800 as the audio clock of the DA converter 680 (S208). .

  Finally, the transmission side device 10 is notified that the reception side device 20 has completed the transition to the second mode (S209).

  Upon receiving this, the transmission side device 10 completes the transition sequence to the second mode (S110).

  In this way, as in the first embodiment, the devices are inquired as to whether or not they can take a special configuration in the second mode, and the operation is performed only when the device has the function. By doing so, it is possible to prevent problems associated with lack of intercompatibility.

  In addition, depending on the system, content that cannot be rate-controlled, such as broadcast reception and repeat transmission of an external input signal, may be handled. In this case, the basic operation mode, which is the conventional mode, is used. Thus, it is the same as in the first embodiment that the problem can be prevented beforehand.

  Further, with the configuration different from that of the first embodiment, functions can be concentrated on the transmission side device 10 side, so that the configuration of the reception side device 20 is simplified, and the effect of simplifying the mode transition sequence is also produced.

  In the data transmission / reception system of the second embodiment as described above, in the second mode, the receiving side device turns the video clock 1 transmitted from the transmitting side device back to the transmitting side device as it is in the second mode. And the audio clock PLL 400 for reproducing the audio clock using the additional data 2 transmitted from the receiving device, and the video clock based on the audio clock reproduced by the audio clock PLL 400 In the second mode, the transmission side is operated by the video clock reproduced by the video clock PLL 500, so that there is no significant fluctuation of the transmission side clock. Adjust the data rate of video and audio data sent from the transmission side on a clock basis. Things can, thereby secured the sound quality of the transmission side, also, it is possible to obtain a system which can also suppress the lip-sync by a frequency deviation of the video clock and the audio clock problem.

(Embodiment 3)
5 and 6 show a configuration of a data transmission / reception system according to the third embodiment of the present invention.
5 and FIG. 6, the same means as those in FIG.
In the third embodiment, the HDMI-2 cable 35 used in the second embodiment is eliminated, and a bidirectional bus of the HDMI-1 cable 15 is used instead.

Next, the operation of the data transmission / reception system 3000 according to the third embodiment will be described with reference to FIG.
The operation in the basic mode is the same as that in the first embodiment, and the operation in the second mode will be described below.

  In the receiving device 20, the PCK globally uses PCK1 received from the transmitting device 10. Similarly, the transmitting device 10 uses PCK1 globally. Since parameter N is a common parameter for transmission and reception, it is sufficient to transmit in the conventional mode.

  Only the CTS that is returned from the receiving device 20 to the transmitting device 10 is an additional parameter in the system, so the CEC line of the HDMI-1 cable 15 is used for this purpose. CEC is a bi-directional bus for mutual control. By putting a CTS parameter (RCTS) returned from the receiving side device 20 to the transmitting side device 10 in this control data, the operation can be performed as in FIG.

  That is, there is an advantage that the HDMI cable can be used in both directions, and a total of two cables can be simplified to one.

  However, the bandwidth that can be transmitted on the CEC bus line is narrow, and there is a possibility that RCTS cannot be transmitted frequently. That is, the margin is insufficient for the required transmission period of 0.7 ms to 3.0 ms.

  FIG. 6 shows a configuration in which the required transmission cycle is multiplied by 1024 in order to solve the shortage of bandwidth margin, which was a problem in FIG.

  In FIG. 6, the configuration of the means 300 for generating the transmission parameter RCTS is changed. Further, in the transmission side device 10, the configuration of the means 400 for reproducing the audio clock 2 is changed from the RCTS parameter. Specifically, the PLL comparison cycle is extended by 1024 times the frequency division number. Such PLL operation tends to increase jitter. In general, this is not preferable because the jitter increases. However, in this third embodiment, this is a configuration using the crystal audio clock 80 having no jitter on the receiving side, and this problem has already been solved. Even if the PLL is used for controlling the data rate, the problem of increased jitter does not occur. That is, by using the PLL having the above configuration, the merit of obtaining the effect of being able to use one HDMI cable is much greater, and an economic effect is achieved.

  In the data transmission / reception system of the third embodiment as described above, in the second mode, the receiving side device uses the audio clock generated by the receiving side device and uses the DA converter provided in the receiving side device. In addition to converting the audio data to analog, the data obtained by counting the period obtained by dividing the audio clock generated by the receiving-side device by the same predetermined frequency division ratio N used in the basic mode with the video clock 1, Based on the audio clock PLL 400 that is transmitted as the additional data 2 and the transmission side device reproduces the audio clock by using the additional data 2 transmitted from the reception side device, and the audio clock reproduced by the audio clock PLL 400 A video clock PLL 500 that reproduces the video clock, and a video reproduced by the video clock PLL 500 in the second mode The transmission side is configured to operate inside the lock, or, in addition, the additional data 2 is further M times the same predetermined frequency division ratio N as that used in the basic mode for the audio clock generated by the second device. (M is an integer greater than or equal to 2) is divided into a longer period, so that the receiving side can be configured to obtain extremely high sound quality without causing large fluctuations in the transmitting side clock. The data rate of video and audio data sent from the network can be adjusted on a clock basis, so that the sound quality on the transmission side can be secured, and the problem of lip sync caused by the frequency deviation between the video clock and the audio clock is also suppressed. In addition, it is possible to obtain a system in which the number of HDMI cables connecting the transmission side and the reception side can be one.

  In each of the above embodiments, the configuration of the apparatus has been described. However, this may be a method using a software process using a program. Moreover, it is convenient for the AV synchronization relationship to be coherent in order to increase the effect, but the original purpose can be achieved even if it is not necessarily coherent.

  The data transmission method, the data reception method, the data transmission device, and the data reception device according to the present invention are useful for a consumer or business use transmission / reception separation type theater system that emphasizes high image quality and high sound quality.

It is a block diagram of the data transmission / reception system 1000 by Embodiment 1 of this invention. It is an operation | movement flowchart of the system in the said Embodiment 1. It is a block diagram of the data transmission / reception system 2000 by Embodiment 2 of this invention. It is an operation | movement flowchart of the system by the said Embodiment 2. FIG. It is a block diagram of the data transmission / reception system 3000 by Embodiment 3 of this invention. FIG. 10 is a configuration diagram of a data transmission / reception system 3010 according to a modification of the third embodiment. It is a block diagram of the conventional data transmission / reception system 7000. FIG. It is a figure which shows the spectrum of various clocks. It is a block diagram of the conventional data transmission / reception system 9000. It is explanatory drawing of the conventional data signal flow control. It is explanatory drawing of the time shift by the deviation of AV clock. It is evaluation explanatory drawing of the time gap by the deviation of AV clock.

Explanation of symbols

1000 data transmission / reception system 2000 data transmission / reception system 3000 data transmission / reception system 3010 data transmission / reception system 10 transmission side device 20 reception side device 15 HDMI-1 cable 35 HDMI-2 cable 100 N, means for generating CTS 200 audio clock reproduction means 300 means for generating transmission parameters N2, CTS2 400 means for reproducing audio clock 2 from second N, CTS parameters 500 PLL for generating pixel clock from audio clock
700 AV data decoding means 800 Crystal oscillation means 850 Transmission side audio clock generation means 900 Transmission side pixel clock generation means

Claims (13)

First transmission means is provided for transmitting video data 1, audio data 1, additional data 1, and video clock 1 from the first device to the second device, and the video clock 1 generated by the first device is the first. It has a basic mode to transmit to 2 devices,
A second mode of transmitting a video clock 2 generated by the second device to the first device, further comprising a second transmission means for transmitting the video clock 2 from the second device to the first device; Have
In the second mode, the first device uses the video clock 2 generated by the second device and transmitted to the first device to transmit video data 1 or audio data 1 transmitted from the first device. Adjust both or one of the data rates ,
When using the video clock 2, the first device transmits the video clock 2 to the second device instead of the video clock generated in the first device,
The first device transmits additional data derived based on the video clock 2 to the second device;
The second device is an audio clock transmitted from the first device, and uses an audio clock generated in the second device instead of an audio clock generated from the additional data. A data transmission / reception system that outputs data. The data transmission / reception system according to claim 1,
The second device includes a DA converter that converts audio data to analog using an audio clock generated by the second device in the second mode.
A data transmission / reception system. The data transmission / reception system according to claim 1,
In the second mode, the second device reproduces the video clock 2 by a phase-locked loop based on an audio clock generated by the second device.
A data transmission / reception system. The data transmission / reception system according to claim 1,
The first device inquires whether or not the second device has the function of the second mode by the control unit of the first device, and determines that the first device has the function when the first device has the function of the second mode. Switch to the second mode and notify the second device that the mode has been switched to the second mode.
A data transmission / reception system. The data transmission / reception system according to claim 1,
The second device inquires whether or not the first device has the function of the second mode by the control unit of the second device, and determines that the second device has the function when the second device has the function of the second mode. Switch to the second mode and notify the first device that the mode has been switched to the second mode.
A data transmission / reception system. The data transmission / reception system according to claim 1,
The first device inquires whether or not the second device has the function of the second mode by the control unit of the first device, and determines that the first device has the function when the first device has the function. If the content data selected on the device cannot change its data rate, leave the operation mode in the basic mode.
A data transmission / reception system. A transmission means for transmitting video data 1, audio data 1, additional data 1, and video clock 1 from the first device to the second device, wherein the video clock 1 generated by the first device is the second device And has a basic mode to transmit to
A transmission means for transmitting the additional data 2 and the video clock 2 from the second device to the first device, and a second mode for transmitting the video clock 2 from the second device to the first device; Have
In the second mode, the second device transmits the video clock 1 transmitted from the first device to the first device as the video clock 2 as it is,
The first device reproduces the video clock based on the audio clock PLL that reproduces the audio clock using the additional data 2 transmitted from the second device, and the audio clock reproduced by the audio clock PLL. A video clock PLL, and in the second mode, operating the first device with the video clock reproduced by the video clock PLL;
When the first device uses the video clock 2, the first device transmits additional data derived based on the video clock 2 to the second device,
The second device is an audio clock transmitted from the first device, and uses an audio clock generated in the second device instead of an audio clock generated from the additional data. A data transmission / reception system that outputs data. The data transmission / reception system according to claim 7,
The second device includes a DA converter that converts audio data to analog using an audio clock generated by the second device in the second mode.
A data transmission / reception system. The data transmission / reception system according to claim 7,
The first device inquires whether or not the second device has the function of the second mode by the control unit of the first device, and determines that the first device has the function when the first device has the function of the second mode. Switch to the second mode, and notify the second device that the mode has been switched to the second mode.
A data transmission / reception system. The data transmission / reception system according to claim 7,
The second device inquires whether or not the first device has the function of the second mode by the control unit of the second device, and determines that the second device has the function when the second device has the function of the second mode. Switch to the second mode and notify the first device that the mode has been switched to the second mode.
A data transmission / reception system. The data transmission / reception system according to claim 7,
The first device inquires whether or not the second device has the function of the second mode by the control unit of the first device, and determines that the first device has the function when the first device has the function. If the content data selected on the device cannot change its data rate, leave the operation mode in the basic mode.
A data transmission / reception system. A transmission means for transmitting video data 1, audio data 1, additional data 1, and video clock 1 from the first device to the second device, wherein the video clock 1 generated by the first device is the second device And has a basic mode to transmit to
A transmission means for transmitting the additional data 2 from the second device to the first device, further comprising a second mode for transmitting the additional data 2 generated by the second device to the first device;
In the second mode, the second device uses the audio clock generated by the second device to convert the audio data into analog by the DA converter provided in the second device, and The data obtained by dividing the audio clock generated by the device 2 with the same predetermined frequency dividing ratio N used in the basic mode and counting with the video clock 1 is transmitted as the additional data 2.
The first device reproduces the video clock based on the audio clock PLL that reproduces the audio clock using the additional data 2 transmitted from the second device, and the audio clock reproduced by the audio clock PLL. A video clock PLL, and in the second mode, operating the first device with the video clock reproduced by the video clock PLL;
When the first device uses the additional data 2, the second device is an audio clock transmitted from the first device and is generated based on the additional data 2. Instead, a data transmission / reception system that outputs audio data using an audio clock generated in the second device . The data transmission / reception system according to claim 12,
The additional data 2 is longer when the audio clock generated by the second device is further divided by M times (M is an integer of 2 or more) the same predetermined frequency division ratio N used in the basic mode. A data transmission / reception system characterized by a period.

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