JP2615763B2 - Digital video signal recording and playback device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video signal recording / reproducing apparatus which can convert a video signal including a video component and an audio component into a digital signal and record or reproduce the digital signal. Related to
More particularly, the present invention relates to a digital video signal recording / reproducing apparatus to which a collation function useful for confirming a recording situation is added.

[Summary of the Invention]

Digital video signal recording / reproducing device (D / VTR) of the present invention
Converts the video signal into a digital signal along with the audio signal,
For example, when recording on a diagonal track of a magnetic tape, a D.VT which is capable of reading recorded information by a magnetic head (ConfidenceHead) for reproducing immediately after the recorded track of the magnetic tape and confirming the recorded content.
In R, the audio signal data input to the D · VTR can be compared with the reproduced audio data via a delay circuit that can vary the delay time, and the recording status of the audio data as well as the video data is confirmed (Verify ).

[Conventional technology]

A digital video signal recording / reproducing device (hereinafter referred to as D-VTR) converts video information and audio information into digital signals respectively, and if necessary, shortens the time axis and rotates the recording track inclined to the longitudinal direction of the magnetic tape. A type in which recording is performed sequentially by a head has been developed.

FIGS. 4 (a) and 4 (b) show an example of the arrangement of a rotary magnetic head and a tape pattern showing the means for recording such a digital video signal. The rotary head D has a pair of recording heads A. ₁ , .B ₁ and A ₂ .B ₂ are provided, and a pair of reproducing heads C _{1 in} a direction orthogonal to the rotary head.
· D ₁ and C ₂ · D ₂ are provided.

Rotating heads A ₁ and B ₁ (A ₂ and B ₂ ) and C ₁ and D ₁ (C ₂
· D ₂₎ each have a different by a height one track width of, for example, the tape running speed and image as image data for one field can be recorded when the drum D is 1.5 turns in the case of the NTSC system Data is being supplied.

Thus, Figure 4 is on a magnetic tape as shown in (b) video data of one field by six tracks T ₁ through T ₆ is recorded, the next one field of the video data in the track T ₇ through T ₁₂ Is recorded.

The center of each track T is a video area V in which video data is recorded, and its entry side and exit side have audio areas a ₁ and a a in which audio data for four channels whose time axis is compressed can be recorded. ₂ , a ₃ and a ₄ are formed.

In a D / VTR of this type, a rotary head A for recording is used.
_The same track is reproduced by a rotating head (dynamic head) C ₁ · D ₁ (C ₂ · D ₂ ) for reproduction while recording video data and audio data in ₁ · B ₁ (A ₂ · B ₂ ). Therefore, if the video data recorded by the recording head is compared with the video data reproduced by the reproducing head, it is possible to immediately confirm (Verify) whether or not the recording of the D / VTR is performed without error. it can.

In this case, the number of rotations of the drum is rotated at an integral multiple of the field frequency of the video signal. Therefore, the delay amount of the video data in the recording / reproducing system may be set to an integral multiple of the number of samples of the video signal. Yes, for example, 1 /
Checking the recording status by comparing the time obtained by adding the data processing time of the recording / playback system to the time of 4 rotations, that is, 1/6 field, with the video data played back as the delay time of the video data recording / playback system Can be.

[Problems to be solved by the invention]

However, there is a problem that it is extremely difficult to perform verification using D.VTR when verifying recorded audio data.

Hereinafter, this point will be described for an audio recording / reproducing circuit.

As shown in FIG. 5, to convert the audio signal S _a by the sampling circuit 1 and A / D converter 2 into a digital signal, a predetermined data processing by the encoder 3 (time warp, the data shuffling error correction Is supplied to the recording rotary head (A / B), and then the reproducing rotary head (C) that tracks the recorded track.
If the audio signal data is reproduced by D) and the reproduced audio signal data is processed again by the decoder 4, the audio data at the time of recording is obtained. Therefore, the audio data output from the decoder 4 and the encoder The comparison circuit 7 compares the audio data input to the
, Data errors occurring in the recording / reproducing system can be detected based on the comparison output.

Therefore, if the comparison output is checked, the recording operation for the D.VTR audio data can be confirmed as well as the video data.

However, the sampling frequency f _as of the audio data
Is standardized to, for example, 48KHz according to the standard in relation to general digital audio equipment. In the case of the NTSC system, the number of samplings in one field period is 80KHz at 48KHz / 59.94.
0.8, which is not an integral multiple.

Therefore, the number of samples of audio data recorded in one field period is, for example, 800 in the first field,
The second field to the fifth field are allocated to be 801. Hereinafter, the period of the five fields is defined as one cycle.
4004 voice data is recorded.

However, since the time difference in the recording / reproducing system of the D.VTR is related to the field period, for example, the sampling period of the video signal is used as a reference, the delay time of the delay circuit 6 shown in FIG. , The comparison phase of the audio data in the comparison circuit 7 is
There has been a problem that matching cannot always be achieved, and a matching function cannot be added to audio data with a simple circuit.

[Means for solving the problem]

The present invention has been made in view of such a problem, and has a detecting means for detecting a delay time in a recording / reproducing system of an ID signal for identifying recording data to be recorded on a track of a tape by a sample period of an audio signal. A delay unit whose delay time is controlled by a detection unit is provided, and audio data before being recorded in the D · VTR is extracted through the delay unit and compared with reproduced audio data.

[Action]

For example, when the time difference related to the recording-reproducing system of the ID signal output at the interval of five fields is detected, the delay time of the data cycle corresponding to the number of 4004 samples which is five times the number of audio sample data of 800.8, which is five times, is detected. Is done.
Therefore, if this delay time is used as the delay control amount of the delay means, the delay time of the delay means can be set by the sample period of the audio data. As a result, the audio data that has passed through the delay means and the reproduced audio data have the same phase, and the recording status of the audio data can be confirmed by comparing and comparing the two.

〔Example〕

FIG. 1 is a block diagram showing a main part of a digital video signal recording / reproducing apparatus according to the present invention. First, in general description, 10A is an A that converts a video signal _SV into a digital signal.
/ D converter, 10B is an A / D converter that converts audio signals to digital signals, 11A is a video data encoder that performs digital signal processing on digital video signals, for example, adding in-line shuffle and outer error codes , A sector array shuffle operation and the like are performed.

An audio data encoder 11B performs digital signal processing on a digital audio signal, and performs operations such as group shuffle, addition of an outer error code, data shuffle, and channel distribution.

Reference numeral 12 denotes data that performs signal processing on a time axis and adds a product code (correction code) to video data and audio data that have been subjected to digital signal processing, and forms data to be recorded in each track sector of the tape. The processing circuit is shown, and then the above-described rotary drum 14
Are supplied to the recording rotary heads (A and B).

Similarly, to the reproduction system, the recording data output from the reproduction rotary head (C / D) is supplied to the reproduction data processing circuit 16 via the reproduction amplifier 15. The reproduction data processing circuit 16 performs data correction, error, and data detection based on the inner code, and outputs video data to the digital video decoder 17A and audio data to the digital audio decoder 17B by signal processing on the time axis.

The digital video decoder 17A outputs baseband video data by performing sector array deshuffling, outer error correction, line deshuffling, and concealment processing, and supplies it to the next D / A converter 18A.

The digital audio decoder 17B performs real-time audio data by performing data shuffling, outer error correction, group deshuffling operation, and the like, and similarly outputs an audio signal from the D / A converter 18B.

According to the present invention, an audio signal input for recording in such a D-VTR is subjected to accurate signal processing and then recorded as predetermined digital data on a tape wound around a drum 14 and running, The audio data converted to a digital signal at a sampling frequency of 48 KHz is used to check whether or not accurate audio data is output when reproduced.
A function of verifying with the reproduced audio data supplied to one input of the digital comparison circuit 21 via the digital comparison circuit 21 via the digital comparison circuit 21 is added.

An audio sample clock A.CLK is supplied to the digital delay circuit 20 to output a signal delayed by a sample period of the audio signal, and is equal to a time difference required for recording and reproducing audio data in the D.VTR as described above. A counter 22 for counting the audio sample clocks A and CLK for providing a delay time, and a control circuit 23 are provided.

Terminal for starting the count value from 0 to counter 22
C ₁ and a terminal C ₂ for stopping the counting operation are provided.
ID signal to the terminal C _1, which is formed based on the synchronization signal of the encoder 11A of the example video system is inputted.

This ID signal is output every five fields of the video cycle, and is formed based on, for example, a V signal.
The ID signal is recorded together with the audio data as head data of the audio track in order to identify the audio data. For example, data such as a channel designation code, the number of samples of audio data to be recorded, a field number, and a track number are added.

Since the audio data is coded at the sampling frequency of 48 KHz as described above, the number of data is 800.8 in one field period, which is an incomplete number as a digital record, but the number of samples is 4004 in the five field period. Therefore, the number of samples of the audio data recorded in the first field is set to, for example, 800, and the number of samples from the second field to the fifth field is set to 801 so as to have a synchronous relationship with the video cycle.

Therefore, as shown in FIG. 2, for example, the counting operation of the audio sample clock (E) input to the counter 23 by the ID signal (A) of the first field added to the audio data (B) is started. When the ID signal (A) of the first field is recorded and then the counting of the counter 22 is stopped by the reproduced ID signal (C), the time difference T required for recording / reproducing the D · VTR is obtained.
Can be detected using the sample period of the audio data as a unit.

In other words, the count value of the counter 22 is controlled so that the time difference required for recording and reproduction by the D · VTR is detected at a multiple of the sample period, so that the count value becomes the delay time of the digital delay circuit 20. When determined by the circuit 23, the digital comparison circuit 21 can compare reproduced audio data (D) composed of the same data as the audio data (B) before recording in the same phase, and output the digital comparison circuit 21 By monitoring, it is possible to evaluate the error rate in the recording-reproducing system of the audio system. Then, when the error rate becomes a certain value or more, a warning can be issued to the user.

In addition, also when the audio data is 4 channels,
It is preferable to provide digital comparison means for each channel. In this case, the delay time for each digital delay circuit can be controlled by a common control circuit 23.

Figure 3 is an illustration of another embodiment of a digital delay circuit and its control circuit, 24 address patrol signal n _a (0, 1,
2, …… N, 1,2, ……)
Denotes an addition circuit, and 26 denotes a readable / writable memory.

The digital delay circuit (cyclic memory means) at classic values of sequential memory 26 by address signal n _a voice data before recording [A _W] is output from the program counter 24 which is driven by the sample clock of the audio read, as an address signal to output value φ values that differ n _b of the first view of the counter 22 that the address n _a program counter 24, and to read the data recorded in the memory 26.

Therefore, the read data [A _R ] is delayed from the recorded audio data [A _W ] by the output value φ of the counter 22, and the read data [A _R ] is compared with the reproduced audio data. As a result, the data of the recording-reproducing system can be collated in phase.

In the above embodiment, the recording method is described in which the audio data is recorded on the entrance side and the exit side of one track as the D.VTR. It goes without saying that the present invention can be applied to the case where the information is recorded in the point.

〔The invention's effect〕

As described above, in the digital video signal recording / reproducing apparatus of the present invention, in a device in which video data and audio data are recorded and reproduced by the rotating head, the sampling frequency of the audio data is set to a value different from the video cycle. Even when it is set, it has a digital delay circuit that sets the delay time at the sample period of the audio data. This makes it possible to record a digital video signal with a high level.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of a D / VTR according to an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining a time difference between a recording and reproducing system, and FIG. FIG. 4 (a) is a block diagram showing another embodiment, FIG. 4 (a) is a layout diagram of a rotary head serving as a recording device of a D / VTR, FIG. 4 (b) is a pattern diagram of a track recorded on a tape, FIG. FIG. 4 is a block diagram showing a method for confirming recording of audio data. In the figure, 20 is a digital delay circuit, 21 is a digital comparison circuit,
22 indicates a counter.

Claims (1)

(57) [Claims] At least a video signal converted into a digital signal, a PCM audio signal, and an identification signal for identifying a number of samples of the PCM audio signal per unit time related to a cycle of the video signal are recorded, In the digital video signal recording / reproducing apparatus capable of immediately reproducing the signals during the recording operation, a delay means for delaying the PCM audio signal before recording, a PCM audio signal delayed by the delay means, Data comparison means for collating the PCM audio signal reproduced by the digital video signal recording / reproduction device, and counter means for counting the time difference required for recording and reproduction of the identification signal in units of a sample clock of the PCM audio signal. ,
The delay time of the delay means is controlled by the output value of the counter means, and the phases of the pre-recorded and reproduced PCM audio signals input to the data comparison circuit are matched. Video signal recording and playback device.