JPH07162806A - Video signal reproducing device - Google Patents

Abstract

PURPOSE:To reproduce natural image sounds at low cost while reducing the time difference between an analog video signal and a digital audio signal by delaying the analog video signal just for the delay time of the digital audio signal while using an image memory. CONSTITUTION:A timing pulse generating circuit 18 generates a clock signal for write corresponding to a synchronizing signal from a synchronizing separator circuit 17 and generates a clock signal for read corresponding to an external reference synchronizing signal from an input terminal 3. Then, these signals are suitably supplied to an A/D converter 11, field memories FM 12-14 and D/A converter 15 so as to control timing for writing/reading an FM demodulated luminance signal converted to a digital signal. At a start signal reproduction processing part 10, FM 13 and 14 are provided in addition to an FM 12, and the same delay time as the delay time part of a PCM audio is prepared. The luminance signal delayed just for this field at the reproduction processing is converted to an analog signal by the D/A converter 15 and outputted from an output terminal 2 after its return component and the unwanted noise component of a residual clock are removed by an LPF 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal reproducing device, and more particularly to a video signal reproducing device for reproducing a video signal from a recording medium in which an analog video signal is recorded and a digital audio signal is recorded. .

[0002]

2. Description of the Related Art In recent years, a video signal recording device called a so-called 8 mm video tape recorder (VTR) for recording video signals and audio signals on a video tape having a width of 8 mm has been widely used.

In this 8 mm VTR, a camera and a VTR are integrated. Further, in this 8 mm VTR, a magnetic tape is wound around a so-called rotary head drum at an angle of 211 degrees, and a pair of heads (hereinafter referred to as rotary heads) 180 degrees apart helically scan the magnetic tape. Therefore, the recording format of the signal recorded on the magnetic tape is as shown in FIG.

That is, when the rotary head helically scans the magnetic tape, an oblique track 61 is formed on the magnetic tape 60 as shown in FIG. Then, in the video area 62 corresponding to 180 degrees of the rotary head drum of each track 61, the luminance signal is FM-modulated, the carrier color signal is converted to a low frequency, and the audio signal is FM-modulated.
A tracking signal for tracking servo, for example, a pilot signal for so-called ATF (Automatic Track Finding) control is frequency-multiplexed and recorded. In addition, the PCM audio area 6 corresponding to about 30 degrees of the remaining rotary head drum of each track 61.
3, a non-linearly quantized digital audio signal (hereinafter referred to as PCM audio signal) is subjected to so-called cross interleave coding processing for error correction, and then a synchronization signal, parity, ID, etc. are added. It will be recorded. A fixed head scans on both sides of the magnetic tape 60 to form a cue track 64 and an audio track 65. The cue track 64 records, for example, a cue signal used for an address of a recorded content, a cue, and the like, and the audio track 65 records an audio signal for after-recording (after recording), for example.

If the recording format as described above is used, in the 8 mm VTR, only the audio signal can be PCM recorded as a digital signal in the PCM audio area 63 in order to emphasize the sound quality. That is, the video signal can be recorded in analog, but the audio signal can be recorded in digital.

The operation until the PCM audio signal is recorded in the PCM audio area 63 and the operation until the PCM audio signal is reproduced from the PCM audio area 63 will be described with reference to FIG. .

First, FIG. 5A is a diagram showing a schematic configuration of a PCM audio signal recording circuit for recording a PCM audio signal in the PCM audio area 63. This P
In the CM audio signal recording circuit, the analog audio signal supplied from the input terminal 71 is supplied to the analog / digital (A / D) converter 72. This A / D
The non-linearly quantized PCM audio signal in the converter 72 is supplied to the PCM recording signal processing circuit 73. This P
The CM recording signal processing circuit 73 applies so-called cross-interleave coding processing for error correction to the PCM audio signal, adds a synchronization signal, parity, ID, etc. Apply compression processing.

That is, the PCM recording signal processing circuit 7
3 is the m-th field, the (m + 1) -th field, and the m-th field shown in (A) of FIG. 6, which have been subjected to cross interleave coding processing and added with a synchronization signal, parity, ID and the like.
+ 2nd field, P of m + 3rd field
The CM audio signal is time-compressed as shown in FIG.

The PCM audio signal, which has been subjected to the predetermined signal processing as described above by the PCM recording signal processing circuit 73, is recorded in the PCM audio area 63 of the magnetic tape 60 by the recording head 75 via the recording amplifier 74. It

Next, FIG. 5B is a diagram showing a schematic structure of a PCM audio signal reproducing apparatus for reproducing a PCM audio signal from the PCM audio area 63. In this PCM audio signal reproducing apparatus, the reproducing head 8
The PCM audio signal 0 played from the magnetic tape is
It is supplied to the PCM reproduction signal processing circuit 78 via the reproduction amplifier 79. The PCM reproduction signal processing circuit 78 performs predetermined processing symmetrical to the PCM recording signal processing circuit 73. The predetermined processing includes time extension processing as shown in FIGS. 6C to 6D.

That is, the PCM reproduction signal processing circuit 7
Reference numeral 8 denotes the m-th field and the m-th field shown in (C) of FIG. The PCM audio signals of the (m + 1) th field, the (m + 2) th field, and the (m + 3) th field are time-expanded as shown in FIG. 6D.

The PCM audio signal which has been subjected to the predetermined signal processing as described above by the PCM reproduction signal processing circuit 78 is supplied to a digital / analog (D / A) converter 77. The audio signal converted into an analog signal by the D / A converter 77 is supplied to an output device such as a speaker via the output terminal 76.

[0013]

By the way, the PCM of the PCM audio signal recording circuit shown in FIG.
A time delay occurs in the audio signal as shown in FIG. 6B in the process of time compression by the PCM recording signal processing circuit 73. That is, the PCM audio signal of the m-th field shown in FIG. 6A is delayed as shown in FIG. 6B.

The PCM audio signal of the PCM audio signal reproducing apparatus shown in FIG.
In the process of time expansion in the reproduction signal processing circuit 78,
A time delay occurs as shown in FIG. That is, the PC of the m-th field shown in FIG.
The M audio signal is delayed as shown in FIG.

Therefore, when the PCM audio signal recorded in the PCM audio area 63 is reproduced for the purpose of sound quality and is viewed together with the analog video signal, the PCM audio signal is compared with the analog video signal. A total of 2-3 fields will be delayed in time.

For example, the time delay of the PCM audio signal with respect to the analog video signal is 2.4 fields 8
Considering the case where so-called dubbing is performed only with the mmVTR, the above-mentioned time delay is further widened. For example,
If dubbing is performed 3 times, the sound is 7.2 for the reproduced video.
Playback is delayed by the field, resulting in a very unnatural playback sound.

The present invention has been made in view of the above-mentioned circumstances, and when a video signal is reproduced from a recording medium in which an analog video signal is recorded and a digital audio signal is recorded, the video and audio signals are reproduced. It is an object of the present invention to provide a video signal reproducing device capable of resolving a time difference at low cost and reproducing a natural image sound.

[0018]

A video signal reproducing apparatus according to the present invention is a video signal reproducing apparatus for reproducing a video signal recorded in a format for recording an analog video signal and a digital audio signal. The above problem is solved by delaying the delay time by the delay time of the digital audio signal using the image memory.

In this case, the analog frequency-modulated audio signal may be delayed by the delay time together with the analog video signal.

Further, the above format may be an 8 mm video tape recording format used when recording a video signal and an audio signal on a video tape having a width of 8 mm.

The image memory may also have a time axis correction function.

[0022]

Since the analog video signal is delayed by the delay of the digital audio signal by using the image memory, the video signal is recorded in analog and the video signal is reproduced when the video signal is reproduced from the recording medium in which the audio signal is digitally recorded. And audio time difference can be solved at low cost, and natural sound can be reproduced.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a video signal reproducing apparatus according to the present invention will be described below with reference to the drawings. This embodiment is capable of recording analog video signals, analog audio signals and digital audio signals.
A video signal reproducing device for reproducing an analog video signal from a video tape of an m video tape recording format, wherein the analog video signal can be delayed by a delay time of a digital audio signal by using a field memory which is an image memory.

As shown in FIG. 1, the video signal reproducing apparatus of this embodiment has a luminance signal reproducing processing section 10 and a chroma signal reproducing processing section 20.

First, the luminance signal reproduction processing section 10 will be described. The FM demodulated luminance signal is input to the input terminal 1. The luminance signal via the input terminal 1 is supplied to the analog / digital (hereinafter referred to as A / D) converter 11 and the sync separation circuit 17. A /
The FM demodulated luminance signal supplied to the D converter 11 is
Converted to digital signal, field memory (F in the figure)
12). On the other hand, the sync separation circuit 17
Separates the sync signal from the supplied FM demodulated luminance signal,
The synchronizing signal is supplied to the timing pulse generating circuit 18 and the timing pulse generating circuit 29.

A field memory 13 is connected to the field memory 12, a field memory 14 is connected to the field memory 13, and a digital / analog (D / A) converter 15 is connected to the field memory 14. A low pass filter (hereinafter referred to as LPF) 16 is connected to the D / A converter 15. That is, between the A / D converter 11 and the LPF 16, the field memories 12, 13 and 14 connected in series and the D / A are connected.
The converter 15 is inserted.

The A / D converter 11, the field memories 12, 13 and 14, and the D / A converter 15 have a writing clock signal generated by the timing pulse generating circuit 18 and a reading clock signal. Signal is supplied.

That is, the timing pulse generation circuit 18
Generates a clock signal for writing in response to the sync signal supplied from the sync separation circuit 17 and a clock signal for reading in response to the external reference sync signal supplied from the input terminal 3, The F converted into a digital signal by supplying the D converter 11, the field memories 12, 13 and 14 and the D / A converter 15 appropriately.
The timing of writing / reading the M demodulation luminance signal is controlled.

Here, the A / D converter 11, the field memories 12, 13 and 14, the D / A converter 15, and the timing pulse generating circuit 18 are time devices which are devices having a time axis correction function. It constitutes the base collector.

This time base collector is a device for removing the jitter when the reproduced signal of the VTR contains a jitter due to the distortion or vibration of the tape and obtaining a stable reproduced signal. The quality of recording and reproducing of information in the VTR is influenced by the speed error due to the relative speed fluctuation of the tape and the head. Therefore, the reproduced video signal of the VTR is once A / D converted and written as digital information in the RAM for storage. The information written in the RAM is flown out at an accurate clock rate by a reference synchronization signal given from the outside. That is, this time base collector is used to restore the signal loss due to jitter to the RA.
By M, the flow of time is stopped for a while, the posture is adjusted, and then the signal is correctly transmitted.

Here, as the time base collector,
For example, at least one field memory 12 can be used as the field memory. However, in the luminance signal reproduction processing section 10, two field memories, such as field memories 13 and 14, are provided, and a PC is used.
The same delay time as the delay time of M audio is realized.

As described above, the luminance signal reproduction processing unit 10
Then, the field memories 12, 13 and 14 are connected in series,
By inserting it between the A / D converter 11 and the D / A 15,
The FM demodulated luminance signal can be redundantly delayed in the reproduction process. That is, an analog video signal, which has no delay in the recording process shown in FIGS. 2A to 2B, is generated in the reproduction process shown in FIGS. 2C to 2D. It becomes possible to delay by 4 fields. In FIG. 2, m,
m + 1, m + 2, and m + 3 indicate field numbers.

The digital luminance signal delayed by 2.4 fields is converted into an analog signal by the D / A converter 15, and unnecessary noise components such as aliasing components and residual clock are removed by the LPF 16 and output. Output from terminal 2.

Next, the chroma signal reproduction processing section 20 will be described. An FM demodulated chroma signal is input to the input terminal 4. The luminance signal via this input terminal 4 is A
It is supplied to the / D converter 21. The FM demodulated chroma signal supplied to the A / D converter 21 is converted into a digital signal and supplied to the decoder 22. The digital chroma signal decoded by the decoder 22 is supplied to the field memory 23.

A field memory 24 is connected to the field memory 23, a field memory 25 is connected to the field memory 24, and an encoder 26 is connected to the field memory 25.
A D / A converter 27 is connected to 6, and an LPF 28 is connected to the D / A converter 27. That is, A /
A decoder 22 and field memories 23, 24 and 25 connected in series are provided between the D converter 21 and the LPF 28.
An encoder 26 and a D / A converter 27 are inserted.

These A / D converter 21 and decoder 22
The field memories 23, 24 and 25, the encoder 26, and the D / A converter 27 are supplied with the write clock signal and the read clock signal generated by the timing pulse generation circuit 29.

That is, the timing pulse generation circuit 29
Generates a clock signal for writing in response to the sync signal supplied from the sync separation circuit 17 and a clock signal for reading in response to the external reference sync signal supplied from the input terminal 3, By appropriately supplying to the D converter 21, the decoder 22, the field memories 23, 24 and 25, the encoder 26, and the D / A converter 27, writing / writing of the FM demodulated chroma signal converted into a digital signal / It controls the read timing.

Here, the A / D converter 21 and the decoder 2
2, the field memories 23, 24 and 25, the encoder 26, the D / A converter 27, and the timing pulse generating circuit 29 constitute a time base collector.

Again, for example, the field memory 24
The field memory 25 is used to increase the delay time by two fields.

Thus, the chroma signal reproduction processing unit 2
Even with 0, by inserting the field memories 23, 24, and 25 in series between the decoder 22 and the encoder 26, the FM demodulated chroma signal can be additionally delayed in the reproduction processing process. That is, the chroma signal reproduction processing unit 20 can also cause the delay of 2.4 fields as described with reference to FIG.

The digital chroma signal delayed by 2.4 fields is converted into an analog signal by the D / A converter 27, and unnecessary noise components such as aliasing components and residual clocks are removed by the LPF 28 and output. It is output from the terminal 5.

As described above, in the video signal reproducing apparatus according to the present embodiment, the luminance signal reproducing processing unit 10 outputs the luminance signal, the chroma signal reproducing processing unit 20 outputs the chroma signal, and two field memories are provided in the time base collector. It is possible to delay by the delay amount of the PCM audio signal as described with reference to FIG. As described above, the video signal reproducing apparatus according to the present embodiment can solve the time difference between the analog video and the digital audio at low cost and reproduce the natural sound.

The video signal reproducing apparatus according to the present invention is
It goes without saying that the present invention is not limited to the above embodiment. Another embodiment will be described below.

For example, an analog frequency-modulated audio signal (hereinafter referred to as an AFM audio signal) is a magnetic tape 60 as described in the prior art with reference to FIG.
In the video area 62 of the track 61 formed above, the signals are frequency-multiplexed and recorded together with the luminance signal, the chroma signal, and the like. Therefore, the reproduced sound of the PCM audio signal with respect to the reproduced sound is equal to a predetermined field, for example, 2.4.
It will be delayed by the field.

Therefore, this AFM audio signal is shown in FIG.
In another embodiment having the configuration as shown in, that is, in the AFM audio signal reproduction processing circuit, the delay time may be delayed by the delay time of the PCM audio signal.

In the AFM audio signal reproduction processing circuit of the other embodiment, as shown in FIG. 3, a demodulated A signal for the left channel inputted from the input terminal 31 for the left channel is inputted.
A recording-side noise reduction processing circuit unit 33 that performs noise reduction processing using AGC (auto gain control) on the FM audio signal and the demodulated AFM audio signal for the right channel input from the right channel input terminal 32. , An A / D converter 36 for converting the AFM audio signal from the recording side noise reduction processing circuit unit 33 into a digital signal, and a static RAM (SRAM) in which the digital audio signal from the A / D converter 36 is recorded. ) Etc. memory 37
And a D / A converter 38 for dividing the digital audio signal read out from the memory 37 after a predetermined time into an analog signal for the left channel and the right channel.
And LPF 39 and LPF 40 for removing unnecessary noise components such as folding components and residual clocks from the left channel analog audio signal and the right channel analog audio signal from the D / A converter 38, and LP
A high-frequency correction circuit 41 and a high-frequency correction circuit 42 for correcting the high-frequency component of the analog audio signal from the F39 and the LPF 40, and a high-frequency corrected left channel from the high-frequency correction circuit 41 and the high-frequency correction circuit 42. A noise reduction processing circuit section 43 on the reproduction side, which performs noise reduction processing on the reproduction side for the analog audio signal and the analog audio signal for the right channel, and outputs from the output terminal 46 for the left channel and the output terminal 47 for the right channel, and A write / read clock signal is appropriately supplied to the A / D converter 36, the memory 37, and the D / A converter 38 according to the synchronization signal supplied from the terminal 48 and the external synchronization signal supplied from the input terminal 49. And a timing pulse generation circuit 50.

Here, the recording side noise reduction processing circuit section 33 comprises a left channel noise reduction circuit 34 and a right channel noise reduction circuit 35, and these noise reduction circuits 34 and 35 are provided. , Level compression is the main operation.

The reproduction-side noise reduction processing circuit section 43 is composed of a left channel noise reduction circuit 44 and a right channel noise reduction circuit 45. These noise reduction circuits 44 and 45 are the main components. Level expansion is performed as a simple operation.

The demodulated AFM audio signal is compressed by the noise reduction circuits 34 and 35 of the recording side noise reduction processing circuit unit 33, converted into a digital signal by the A / D converter 36, and then stored in the memory 37. Written in. The timing of this A / D conversion and the timing of writing are controlled by the clock signal supplied from the timing pulse generation circuit 50.

The timing pulse generating circuit 5
0 supplies a read clock to the memory 37, for example, 2.4 fields after the write timing, reads the digital FM audio signal, and outputs it to the D / A converter 38. The D / A converter 38 is also supplied with a clock from the timing pulse generation circuit 50, converts the digital audio signal into an analog audio signal at a predetermined timing and outputs it to the LPF 39 and the LPF 40.

As described above, also in this AFM audio signal reproduction processing circuit, the A / D converter 36, the memory 37,
The write / read clock from the timing pulse generation circuit 50 is supplied to the D / A converter 38 to write / read.
By controlling the read timing, the AFM audio signal can be delayed by a predetermined time, for example, 2.4 fields.

Then, for example, the AFM audio signal delayed by 2.4 fields is supplied to LPFs 39 and 40,
It is supplied to the recording-side noise reduction processing circuit section 43 via the high-frequency correction circuits 41 and 42. In the recording-side noise reduction processing circuit section 43, the noise is reduced by the noise reduction circuits 34 and 35 of the reproducing-side noise reduction processing circuit section 33, and the A / D converter 36, the memory 37 and the D
The AFM signal delayed by 2.4 fields via the A / A converter 38 is supplied to the LPFs 39 and 40 and the high frequency correction circuit 41.
And 42, and noise reduction circuits 44 and 4
It is expanded by 5 and output from the output terminals 46 and 47.

As described above, in the AFM audio signal reproduction processing circuit of the other embodiment, the writing / writing in the memory 37 is performed.
By appropriately controlling the reading by the timing pulse generation circuit 50, the AFM audio signal can be delayed by the delay of the PCM audio signal at low cost.

The video signal reproducing apparatus according to the present invention is
Since it is sufficient to reproduce the video signal recorded in the format for recording the analog video signal and the digital audio signal, it may be applied to an apparatus for reproducing the video signal recorded on the disc-shaped recording medium.

[0055]

The video signal reproducing apparatus according to the present invention is a video signal reproducing apparatus for reproducing a video signal recorded in a format for recording an analog video signal and a digital audio signal, wherein the analog video signal is stored in an image memory. Since it is delayed by the delay time of the digital audio signal by using it, the time difference between the video and the audio can be solved at low cost, and a natural sound can be reproduced.

The video signal reproducing apparatus according to the present invention can delay not only the analog video signal but also the analog frequency-modulated audio signal by the delay time of the digital audio signal at low cost.

Since the image memory used in the video signal reproducing apparatus according to the present invention is also provided with the time base collector function, the circuit scale can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a video signal reproducing device according to the present invention.

FIG. 2 is a timing chart for explaining the operation of the embodiment shown in FIG.

FIG. 3 is a block diagram showing a schematic configuration of another embodiment of the video signal reproducing device according to the present invention.

FIG. 4 is a diagram showing a recording format of an 8 mm VTR.

FIG. 5 is a block diagram showing a PCM audio signal recording circuit and a PCM audio signal reproducing circuit of an 8 mm VTR.

6 is a timing chart for explaining the operation of the PCM audio signal recording circuit and the PCM audio signal reproducing circuit of the 8 mm VTR shown in FIG.

[Explanation of symbols]

 11 ... Analog / Digital (A / D) Converter 12, 13, 14 ... Field Memory 15 ... Digital / Analog (D / A) Converter 16 ... Low-pass filter (LPF) 17 ... Synchronous separation circuit 18 ... Timing pulse generation circuit 21 ... A / D converter 22 ... Decoder 23, 24, 25 ... ..Field memory 26 ... Encoder 27 ... D / A converter 28 ... LPF 29 ... Timing pulse generation circuit

Claims (4)

[Claims] 1. A video signal reproducing apparatus for reproducing a video signal recorded in a format for recording an analog video signal and a digital audio signal, wherein the analog video signal is delayed by a delay time of the digital audio signal by using an image memory. A video signal reproducing device characterized by delaying. 2. The video signal reproducing apparatus according to claim 1, wherein an analog frequency modulation audio signal is delayed by the delay time together with the analog video signal. 3. The video signal reproducing apparatus according to claim 1, wherein the format is an 8 mm video tape recording format used when recording a video signal and an audio signal on a video tape having a width of 8 mm. 4. The video signal reproducing apparatus according to claim 1, wherein the image memory also has a time axis correction function.