JP3159224B2 - Video / audio multiplexed signal playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reproducing a video / audio time division multiplexed signal.

[0002]

2. Description of the Related Art The current standard television system is NTSC.
As a television system having a higher quality, a so-called high-vision system has been developed. When using the HDTV system, the amount of information is about five times that when using the NTSC system.
It cannot be transmitted by satellite broadcasting, video disc, VTR, etc. For this reason, a video signal according to the Hi-Vision system is transmitted after being subjected to data compression so as to have a baseband width of, for example, about 8 MHz by a multiplex sub-sampling system.

The multiplex sub-sampling method is basically dot interlace transmission, and a sampling pattern is repeated at an offset between frames, between fields, and between lines at a period of four fields, and a resample clock rate is a line sampling rate. 16.2 MHz for 480 dots
It is said. The scanning format is 1125 lines, 60 fields, and 2: 1 interlace, as in the HDTV system.

Further, in the multiplex sub-sampling method, a video signal (luminance signal Y, chrominance signal C), audio data, and an independent additional information signal are formed on a time axis in a format shown in FIG. Multiplexed. In this case, the audio data is obtained by encoding the audio signal by the quasi-instantaneous compression / expansion DPCM method. An audio synchronization code is added to the audio data, and the audio data having the audio synchronization code is added to the additional information signal. Is multiplexed together with the time axis compression.

References Ninomiya: Journal of the Institute of Television Engineers of Japan, No.
Vol. 42, No. 8, 1988

[0006]

When the above-described multiplex sub-sampling method is applied to, for example, a video disk, the video disk player generally outputs the time-division multiplexed video as shown in FIG. The signal and the audio data are output as multiplexed. This is because a decoder for separating and decoding the original video signal and audio signal from the time-division multiplexed signal is expensive, and the user can share the decoder with a video disc player or a satellite broadcast receiver. This is in order to reduce the economic burden.

However, for example, in the still image reproduction mode,
The same audio data is repeatedly reproduced, and in the high-speed reproduction mode, the audio data is reproduced intermittently. That is, in the reproduction modes of special reproduction (variable reproduction) such as still image reproduction, forward and reverse slow reproduction, and high-speed reproduction, audio data is not reproduced in the same state as at the time of recording, and the continuity of the audio data is lost. I will be.

When the audio data whose continuity has been lost is supplied to a decoder of the multiplex sub-sampling method and decoded, the audio data is synchronized or desynchronized by an audio synchronization code included in the audio data. As a result, the decoded output becomes a noise signal, and this noise signal is output as a reproduced audio signal as it is.

In view of the foregoing, the present invention is to prevent a noise signal from being output in a special playback mode in a playback apparatus that outputs a video / audio time division multiplexed signal as it is.

[0010]

Therefore, according to the present invention, when the reference numerals of the respective parts correspond to the embodiments described later, the audio data including the audio synchronizing code is multiplexed in a time-division manner, and is multiplexed together with the video signal. A frame synchronization separation circuit 31 for separating a frame synchronization signal S31 in the output signal S11 in a playback device 10 configured to reproduce the recorded recording medium VD and obtain a video / audio time-division multiplexed signal as an output signal S11; A line synchronization separation circuit 34 for separating the line synchronization signal S34 in the output signal S11, and a gate signal S39 corresponding to the section of the audio data in the output signal S11 based on the separated frame synchronization signal S31 and line synchronization signal S34. And a gate signal forming circuit 30 for forming the same. And
In the special reproduction mode, the output signal S is determined by the gate signal S39.
Only the section of the audio data in 11 is fixed to an arbitrary signal not including the audio synchronization code, for example, a predetermined potential.

[0011]

In the special reproduction mode, during the period of the audio data in the video / audio time-division multiplexed signal S11, the audio signal of the decoder 50 is muted to prevent the output of the noise signal as the reproduced audio signal. To

[0012]

FIG. 1 shows an example in which the present invention is applied to an optical video disk player of a multiplex sub-sampling system, and FIGS. 2 and 3 are waveform diagrams thereof. However,
In this waveform diagram, the right side of FIG. 2 is followed by the left side of FIG.

In FIG. 1, VD is an optical video disk on which a video signal and audio data including an audio synchronization code are subjected to multiple sub-sampling and time division multiplexing and recorded in the format shown in FIG. Numeral 10 is a video disk player and numeral 50 is a multiplex subsampling decoder.

Further, in the player 10, reference numeral 11 denotes a reproduction circuit thereof, reference numeral 21 denotes a system controller constituted by a microcomputer, and the reproduction circuit 11 includes an optical pickup, an equalizer circuit, a demodulation circuit, a frame memory, and the like. Controls the operation mode. In the normal reproduction mode, the reproduction circuit 1
1 reproduces and takes out the video / audio time-division multiplexed signal S11 recorded on the video disk VD, and supplies this signal S11 to the switch circuit 12.

Further, a signal S21 which becomes "H" in the normal reproduction mode is extracted from the system controller 21, and this signal S21 is supplied to the switch circuit 12 through the OR circuit 22 as a control signal thereof. Connected to. Thus, in the normal reproduction mode, the signal S11 is taken out to the output terminal 14 through the switch circuit 12.

The signal S11 taken out of the terminal 14 is supplied to a decoder 50, where the original video signal and audio signal are separated and decoded from the signal S11. Respectively.

On the other hand, in the special reproduction mode, the system controller 2
The control signal S21 from “1” becomes “L”, and the switch circuit 12 is controlled by the gate signal S39 from the gate signal forming circuit 30.

That is, the signal S11 from the reproducing circuit 11
Is supplied to the frame synchronization separation circuit 31, and as shown in FIG. 2A, a frame synchronization signal S31 is taken out. This signal S31 is supplied to the line counter 32 as a load input, and the count value of the counter 32 becomes "2". Is set.
Further, the signal S11 from the reproduction circuit 11 is supplied to a line synchronization separation circuit 34, and as shown in FIG. 2B, a line synchronization signal S34 is extracted, and this signal S34 is supplied to the counter 32 as its count input. Note that the counter 3
The count value of 2 is set to “2” because the frame synchronization signal S31 rises at the start of the period of the line number 2.

Therefore, for each frame period, the counter 32 counts the number of lines in that frame period from "2".

Then, the count value of the counter 32 is supplied to the decoder 33, and the decoder 33 outputs the count value shown in FIG.
As shown in FIG. 2, the signal S1 which becomes "H" during the period of the line number of 3-46 and the period of 565-608 of each frame is taken out, and as shown in FIG. 2D, the line number of each frame becomes The signal S2 which becomes "H" during the periods 43 to 46 and 605 to 608 is taken out. And the signal S
1 is supplied to the NAND circuit 39, and the signal S2 is supplied to the AND circuit 38.

The signal S34 from the separation circuit 34 is supplied to the sample counter 35 as a reset input. Further, the signal S34 is supplied to the PLL 37 to form a clock synchronized with the signal S34 and having a frequency equal to the resample clock frequency (16.2 MHz) of the signal S11. This clock is supplied to the counter 35 as a count input. You.

Therefore, the counter 35 counts the number of samples in the line period from "0" for each line period.

The count output of the counter 35 is supplied to a decoder 36, and the decoder 36 outputs a sample number of 12 to 10 for each line as shown in FIG.
The signal S3 which becomes "H" during the period of 5 is extracted, and the signal S4 which becomes "H" during the period of the sample numbers 1 to 11 of each line is extracted as shown in FIG. 2F.
Then, the signal S3 is supplied to the AND circuit 38, and the signal S3
4 is supplied to the inverting input of the NAND circuit 39,
The output signal S38 of the AND circuit 38 is supplied to the inverted input of the NAND circuit 39.

Therefore, the output signal S of the AND circuit 38
38 becomes "H" in the cycle shown in FIG. 2G, the output signal S39 of the NAND circuit 39 becomes "H" in the cycle shown in FIG. 2H. That is, the signal S39 becomes "L" during the period of the audio data in FIG. 4, and becomes "H" during other periods.
Becomes

The signal S39 is supplied to the switch circuit 12 through the OR circuit 22 as a control signal.

Then, in the special reproduction mode, S21 =
Since it is “L”, the switch circuit 12 is switched according to the signal S39, and during the period of the audio data in FIG. 4, the DC voltage from the DC voltage source 13 is
The signal is taken out to the terminal 14 through the switch circuit 12, and in another period, the reproduction signal S 11 from the reproduction circuit 11 is taken out to the terminal 14 through the switch circuit 12.

Therefore, in the special reproduction mode, the signal other than the audio data among the reproduction signals S11 from the reproduction circuit 11 is supplied to the decoder 50 as it is, so that the video signal by the special reproduction can be obtained at the terminal 51. .
However, in the reproduction signal S11 from the reproduction circuit 11, during the period of the audio data, the DC voltage from the voltage source 13 is supplied to the decoder 50. Is muted and no audio signal is output.

Thus, according to the present invention, in the special reproduction mode, during the period of the audio data, the audio signal system of the decoder 50 is muted, so that the output of the noise signal as the reproduced audio signal is prevented. Is done.

In the above description, a case has been described in which the present invention is applied to an optical video disc player of a multiplex sub-sampling method, but the present invention can also be applied to a similar VTR or the like. Further, in the above description, the section of the audio data is fixed to the predetermined DC potential, but the audio data can be replaced with dummy audio data not including the audio synchronization code, for example, the output of the random pattern generation circuit.

[0030]

According to the present invention, a video / audio multiplexed signal player 1 which outputs a multiplexed signal as it is.
0, a gate signal S39 corresponding to the audio data section of the reproduction signal S11 is formed based on the frame synchronization signal S31 and the line synchronization signal S34 of the reproduction signal S11. Signal S11
Is output after changing the section of the audio data to a signal not including the audio synchronization code. In the special reproduction mode, the audio signal system of the decoder 50 is muted, and the decoder 50 outputs a noise signal as a reproduced audio signal. Can be prevented from being output.

Since the reproduction signal S11 supplied from the player 10 to the decoder 50 prevents the output of a noise signal as a reproduced audio signal, the output of the noise signal from the player 10 to the decoder 50 is prevented. There is no need to separately supply a control signal for preventing the occurrence of a noise signal, and therefore, it is not necessary to provide a special decoder 50, and any decoder can output a noise signal as an audio signal. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an example of the present invention.

FIG. 2 is a waveform chart for explaining the operation of the circuit of FIG. 1;

FIG. 3 is a waveform diagram following FIG. 2;

FIG. 4 is a conceptual diagram of a signal format in a multiple subsampling method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Video disk player 11 Reproduction circuit 13 DC voltage source 21 System controller 30 Gate signal formation circuit 31 Frame synchronization separation circuit 32 Line counter 33 Decoder 34 Line synchronization separation circuit 35 Sample counter 36 Decoder 50 Multiple subsampling decoder VD Optical video disk

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/76-5/956 G11B 20/02

Claims (3)

(57) [Claims] A reproducing apparatus for reproducing a recording medium in which audio data including an audio synchronization code is multiplexed in a time-division manner and recorded together with a video signal, and obtaining a video-audio time-division multiplexed signal as an output signal. In the above, based on the separated frame synchronization signal and the line synchronization signal, a frame synchronization separation circuit for separating the frame synchronization signal in the output signal, a line synchronization separation circuit for separating the line synchronization signal in the output signal A gate signal forming circuit for forming a gate signal corresponding to the section of the audio data in the output signal; and outputting a signal indicating the special reproduction mode in the special reproduction mode.
Control signal, and the gate signal and the signal indicating the special reproduction mode.
A video / audio multiplexed signal reproducing apparatus , comprising: a switch circuit for controlling only the section of the audio data in the output signal to output a signal not including the audio synchronization code. 2. A video / audio multiplexed signal reproducing apparatus according to claim 1, wherein the signal not including the audio synchronization code is a signal of a predetermined DC potential. 3. The reproducing apparatus according to claim 1, wherein the signal not containing the audio synchronization code is dummy audio data.