JP3232788B2 - Digital video signal recording and reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video signal recording / reproducing apparatus for converting a PALplus television signal into digital data and recording it.

[0002]

2. Description of the Related Art There has been proposed a digital VTR which converts an analog video signal from analog to digital and compresses and records the data. FIG. 7 is a block diagram showing an example of a video signal recording / reproducing system in such a digital VTR. First, a digital VTR will be described with reference to FIG.

The input analog component video signal (Y, U, V) is converted into a digital component video signal by an A / D converter 11, and eight blocks in the horizontal direction and eight lines in the vertical direction (hereinafter referred to as “8”) are output by the blocking circuit 12. × 8 units) into one block of data, and four Y signal blocks, U
A macroblock is composed of a total of six blocks, one for each of the signal and V signal blocks, and shuffling and Y / C multiplexing are performed in macroblock units. The 8 × 8 unit data is subjected to discrete cosine transform by the DCT circuit 13, and data in the time amplitude domain is converted into data in the frequency domain. The data subjected to the discrete cosine transform is the encoder 1
4 and are variable-length coded by a two-dimensional Huffman code or the like, and are data-compressed. In this case, the step width in the requantization is set so that the total data amount for each buffering unit composed of a predetermined number of macroblocks (eg, 5 macroblocks) does not exceed a certain amount. Next, in the framing circuit 15,
A plurality of such buffering units are vertically arranged to form a frame.
CC (Error Correction Code)
After adding a parity of the product code configuration, the data is converted into serial data by the channel encoder 17 and recorded on a magnetic tape (not shown).

At the time of reproduction, data detection and serial / parallel conversion are performed by the channel decoder 18, and ECC is performed.
The circuit 19 performs error correction. The error-corrected data is decomposed into word units of a variable-length code by a deframing circuit 20, decoded and dequantized by a decoder 21, and subjected to inverse discrete cosine transform by an inverse DCT circuit 22 to obtain data of 8 × 8 units. Become. The data is subjected to deshuffling, Y / C separation, data interpolation, and the like by the deblocking circuit 23, and is returned to a digital component video signal. The D / A converter 24 converts the data to an original analog component video signal and outputs it. .

Although the U signal and the V signal are actually input and output to and from different signal lines, in this specification, they are described as one signal line for convenience.

The digital VTR constructed as described above
For example, when a video signal of the PAL system is recorded by 4: 2: 0 component coding, as shown in FIG. Since data of 576 samples in the direction is processed, 90 blocks in the horizontal direction and 72 blocks in the vertical direction are arranged in 8 × 8 units. Similarly, as for the U signal and the V signal, as shown in FIG.
Since 0 samples and 288 samples of data in the vertical direction are processed, 45 blocks of 8 × 8 units are processed in the horizontal direction.
There will be 36 in the vertical direction. Then, FIG.
As shown in (1), a macroblock is composed of four blocks of the Y signal and one block of the U signal and the V signal, for a total of six blocks.

When such macroblocks are viewed over the entire screen of one frame, as shown in FIG. 9, there are a total of 1620 macroblocks, 45 in the horizontal direction and 36 in the vertical direction.

Then, as shown in FIG. 10, the video data of the 1620 macroblock is divided into 12 tracks, and therefore, the video data of 135 macroblocks per track is divided into oblique tracks T0 to T0 on the magnetic tape MT. Record at T11.

As the EDTV standard in Europe, the current P
PALplus that realizes a wide screen while maintaining compatibility with the AL system (Compatibility)
A scheme has been proposed. First, the outline of the PALplus system will be described with reference to FIGS.

FIG. 11 shows an image from a PALplus system source to a receiver. First, the source has 720 effective samples in the horizontal direction as shown in FIG.
The number of effective scanning lines in the vertical direction is 576 (however, in the case of the Y signal, the number of effective samples in the U and V signals is 360 in the horizontal direction), and the image signal has an aspect ratio of 16: 9. .

This image signal is subjected to a process of thinning out one for every four lines in the vertical direction, and as shown in (b), a main image in which the number of vertical scanning lines is reduced to 432 lines. Converted to a signal. Then, a difference signal between the Y signal component of the thinned scanning line and the average level of the upper and lower scanning lines is created, and is used as a helper signal as shown in (c).
As shown in (d), the main image signal and the helper signal are transmitted as an image signal having an aspect ratio of 4: 3 by a letterbox system in which the helper signal is multiplexed above and below the main image signal. At this time, an identification code indicating that the signal is a PALplus signal is inserted in the vertical blanking period of the image signal.

On the image receiving side, when an image is received by a current PAL-type receiver that does not have a PALplus-type decoder, as shown in (e), 432 scanning lines corresponding to the main image signal are received. Helper signals are displayed above and below the image. However, this helper signal is inconspicuous because it is at a low level, has a high frequency component, and is at the edge of the screen.

On the other hand, when an image is received by a receiver equipped with a PALplus type decoder, an identification code is detected and P
The signal of the ALplus system is identified, and a signal of a scanning line thinned out on the image transmitting side is created based on the helper signal. Then, since the original 576 scanning lines are restored,
As shown in (f), an image having an aspect ratio of 16: 9 having 576 scanning lines is displayed.

FIG. 12A is a block diagram showing a PALplus encoder. First, the Y signal, the U signal, and the V signal signal are input to the letter box processing circuit 31, where one scanning line is thinned out every four lines, and FIG.
The signal shown in (b) is supplied to the PAL encoder 32. The helper signal shown in FIG. 11C is supplied to the helper signal modulator 33.

The PAL encoder 32 has 4.43 MH
The sub-carrier of z is supplied to create a PAL television signal. The helper signal modulator 33 is also supplied with a subcarrier of 4.43 MHz, and VSB modulation is performed by the helper signal.

The output of the PAL encoder 32 and the output of the helper signal modulator 33 are output from a synthesizing circuit 34 as shown in FIG.
As shown in (d), the signal is synthesized to be a PALplus television signal and transmitted.

FIG. 12B is a block diagram showing a PALplus decoder. First, a PALplus television signal is separated by a separation circuit 41 into a modulated helper signal and a PAL main image signal. Then, the modulated helper signal is demodulated into a helper signal by the helper signal demodulator 43 and supplied to the inverse letterbox processing circuit 44. Also, PA
The main image signal of the L system is converted to Y,
U and V signals are separated into inverse letterbox processing circuits 44
Supplied to The inverse letterbox processing circuit 44 creates the scanning lines thinned out on the image transmission side, and restores and outputs 576 scanning lines as shown in FIG. Since the helper signal does not include the U signal component and the V signal component,
The U and V signals are restored from the upper and lower scanning lines.

[0018]

SUMMARY OF THE INVENTION Such a PALpl
When a us-type television signal is recorded on a digital VTR, the PALplus-type television signal is decoded by the PALplus decoder shown in FIG. 12B to create an analog component video signal, which is input to the recording system shown in FIG. It is possible to do.

However, with such a configuration, it is necessary to provide a PALplus decoder in the digital VTR, which causes a problem that the circuit scale of the digital VTR becomes large.

The present invention has been made in order to solve such a problem, and provides a digital video signal recording / reproducing apparatus capable of recording a PALplus television signal without providing a PALplus decoder. The purpose is to:

[0021]

In order to solve the above-mentioned problems, the present invention relates to an apparatus for converting a PALplus television signal into digital data and recording the same, wherein the PALplus television signal is provided. First means for demodulating a helper signal from PALplus, second means for converting the helper signal demodulated by the second means into uncompressed digital data, and PALplus
Means for converting a main image signal separated from a television signal of a system into compressed digital data, and recording the output of the second means and the output of the third means in another area of a recording medium. Means.

Further, the invention according to claim 2 is a PALpl
a first means for demodulating a helper signal from a PALplus television signal in an apparatus for converting a US television signal into a digital signal and recording the digital signal;
A second means for amplifying the helper signal demodulated by the first means, and a third means for converting the output of the second means and the main image signal separated from the PALplus television signal into compressed digital data. And a fourth means for recording the output data of the third means on a recording medium.

[0023]

According to the first aspect of the present invention, PALplus
Demodulates only the helper signal from the television signal
Convert to uncompressed digital data. Also,
The main image signal separated from the PALplus television signal is converted into compressed digital data.
Then, the uncompressed digital data and the compressed digital data are recorded in different areas of the recording medium.

According to the second aspect of the present invention, PALpl
Only the helper signal separated from the us television signal is demodulated and amplified. Then, the digital signal is converted into digital data compressed together with the main image signal separated from the PALplus television signal and recorded.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic block diagram of a video signal processing system of a digital video signal recording and reproducing apparatus according to an embodiment of the present invention. In this figure, FIG.
The parts corresponding to are denoted by the same reference numerals.

In FIG. 1, the PALplus television signal output from the tuner 1 is separated by a separation circuit 4.
1, the main image signal is supplied to a Y / C separation circuit 42, and the helper signal is supplied to a helper signal demodulator 43. The main image signal is separated into Y, U, and V signals by a Y / C separation circuit 42, the Y signal is supplied to a switching circuit SW, and the U and V signals are supplied to a recording / reproducing system 4. The helper signal is demodulated by the helper signal demodulator 43, and the switching circuit S
W. Y supplied to the switching circuit SW
The signal and the helper signal are switched at a predetermined timing and supplied to the recording / reproducing system 4. In the recording / reproducing system 4, the inputted Y signal, U signal, V signal and helper signal are digitized and recorded and reproduced (details will be described later).

Thus, according to the present invention, PALplus
Since the helper signal is demodulated and supplied to the recording / reproducing system 4 without completely decoding the television signal of the TV system, the PA
In the Lplus decoder, the inverse letterbox processing circuit 44 having a large circuit scale is not required.

Next, the configuration of the recording / reproducing system 4 will be described. (First Embodiment) FIG. 2 is a block diagram of a first embodiment of the recording / reproducing system. Here, parts corresponding to those in FIG. 7 are given the same numbers.

In this figure, a Y signal and a helper signal are converted into an A / D signal by a first switching circuit SW1.
The helper signal is supplied to the A / D converter 2
5 to be supplied. The U signal and the V signal are supplied to the A / D converter 11.

The Y signal supplied to the A / D converter 11, U
The processing until the signal and the V signal are output from the encoder 14 is basically the same as in the case of FIG. On the other hand, the helper signal is converted into a digital signal by the A / D converter 25 at a lower sampling frequency and a smaller number of bits (for example, 6.75 MHz, 4 bits) than the Y signal component of the main image signal, and stored in the memory 26. Is done.

The output of the encoder 14 and the output of the memory 26 are input to the framing circuit 15 via the second switching circuit SW2. In the framing circuit 15, the buffering unit output from the encoder 14 and the digitized helper signal output from the memory 26 (hereinafter referred to as a digital helper signal)
Are framed according to a track format described later. At this time, the ID code extracted from the vertical blanking period of the PALplus television signal is added to the buffering unit. The output of the framing circuit 15 is added with parity of a product code configuration in a parity generation circuit 16 and then output from a channel encoder 17.
To convert the data into serial data and record it on a magnetic tape.

Here, the blocking operation and the track format in this embodiment will be described. When the main image signal is recorded by 4: 2: 0 component coding, as for the Y signal, as shown in FIG. 3A, data of 720 samples in the horizontal direction and 432 samples in the vertical direction per frame. Is processed, so 8 ×
90 blocks of 8 units horizontally and 54 blocks vertically
Will be lined up. Similarly, as for the U signal and the V signal, as shown in FIG. 3B, data of 360 samples in the horizontal direction and 216 samples in the vertical direction are processed per frame, respectively, so that 8 × 8 units are used. There are 45 blocks in the horizontal direction and 27 blocks in the vertical direction.

As shown in FIG. 8C, when a macro block is composed of four blocks of Y signals and one block of U and V signals, that is, a total of six blocks, the entire screen of one frame is obtained. As shown in FIG. 4, there are a total of 1215 macroblocks, 45 in the horizontal direction and 27 in the vertical direction.

Comparing this with the case of FIG. 9, one frame has 405 macroblocks and one track has 33.
Since 75 macro blocks are reduced, a digital helper signal is recorded in this portion.

FIG. 5 shows an example of the track format. In this pattern, a main image signal is recorded on the entrance side of the track, and a digital helper signal is recorded on the exit side. However, since it is necessary to arrange an integer number of macroblocks for each track, recording is performed so that 12 tracks are 1215 macroblocks.

As another example of the track format,
For example, out of 12 tracks, predetermined 9 tracks (eg,
The main image signal can be recorded on T0 to T8), and the digital helper signal can be recorded on the remaining three tracks (eg, T9 to T11).

Next, the sampling frequency and the number of bits of the main image signal and the helper signal will be described. In the digital VTR of FIG. 7, the Y signal is 13.5 MH
The z, U and V signals are sampled at 6.75 MHz and quantized with 8 bits each. Then, the video data thus digitized is converted to approximately 25 Mbp.
s. Therefore, in this embodiment, 25
6.25 Mbps, which is 1/4 of Mbps, can be allocated to the digital helper signal. The helper signal is converted to a half of the sampling frequency of the Y signal at 6.75 MH.
When sampling is performed by z and quantized by n bits,
(720/2) × (576/4) × n × 30 ≒ n × 1.
It becomes 56 Mbps. Therefore, it is possible to quantize and record with n = 4 bits.

The data thus recorded is subjected to data detection and serial / parallel conversion by the channel decoder 18, error correction by the ECC circuit 19, and is supplied to the deframing circuit 20. The deframing circuit 20 decomposes the buffering unit into variable-length code words and outputs the third switching circuit SW3
To the decoder 21 via the. Further, the deframing circuit 20 supplies the digital helper signal to the memory 27 via the third switching circuit SW3.

The data supplied to the decoder 21 is shown in FIG.
As in the case of (1), the data is decoded, inversely quantized, and inverse discrete cosine transformed by the inverse DCT circuit 22 to become data of 8 × 8 units. This data is subjected to deshuffling, Y / C separation, data interpolation and the like by the deblocking circuit 23, and is returned to a digital component video signal.
The signal is converted into the original analog component video signal (Y, U, V) by the converter 24 and output. Then, in the adder 29, the PALpl separated from the reproduction data is obtained.
The ID for identifying the us system is reinserted during the vertical blanking period of the Y signal.

On the other hand, the digital helper signal stored in the memory 27 is read out at a predetermined timing,
The signal is converted by the A converter 28 into the original helper signal.

The Y signal output from the adder 29 and D / A
The helper signal output from the converter 28 is output via the fourth switching circuit 4. Also, the U signal and V
The signal is output directly from the D / A converter 28.

As described above, in this embodiment, since the helper signal is recorded and reproduced without being compressed, the helper signal does not receive quantization distortion.

(Second Embodiment) FIG. 6 is a block diagram of a second embodiment of the recording / reproducing system. Here, parts corresponding to those in FIG. 1 are given the same numbers.

In this embodiment, the Y signal and the helper signal are input to the A / D converter 11 via the boost-amplifier 31. The boost-amplifier 31 is configured to amplify, for example, 6 dB by the control signal only during the period when the helper signal is input. The Y signal, helper signal, U signal, and V signal input to the A / D converter 11 are processed and recorded in the same manner as in the case of FIG. Therefore, in this embodiment, the helper signal is also compressed, encoded, and recorded together with the Y signal and the like. In this embodiment, similarly to the first embodiment, the framing circuit 15 adds an ID for identifying the PALplus system to the buffering unit.

At the time of reproduction, processing is performed in the same manner as in the case of FIG.
From the D / A converter 24, a Y signal, a helper signal, a U signal,
A V signal is output. Then, as in the first embodiment, in the adder 29, the PALpl
The ID for identifying the us system is reinserted during the vertical blanking period of the Y signal. The output of the adder 29 is output via the attenuator 32. The attenuator 32 controls the boost-amplifier 3 only during the period when the helper signal is input by the control signal.
It is configured to attenuate by the amount amplified by 1.

As described above, in this embodiment, since the level of the helper signal, which is a low-level signal, is increased, it is possible to prevent the helper signal from being subjected to quantization distortion in the DCT circuit. Further, the recording / reproducing system from the A / D converter 11 to the D / A converter 24 has no special difference from the PAL system shown in FIG.
It is easy to use in common with the digital VTR of the AL system.

[0047]

As described in detail above, according to the present invention, only the helper signal is demodulated and recorded.
It is possible to record a PALplus television signal without providing an ALplus decoder.

Further, since the helper signal is recorded without data compression or amplified and then recorded with data compression, it can be recorded without receiving quantization distortion due to compression. For this reason, the recording medium is reproduced, and PALplu is read.
A good image can be reproduced even if the s-system signal is decoded.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a video signal processing system of a digital video signal recording and reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of a first embodiment of a recording / reproducing system according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating a blocking operation in the embodiment of the present invention.

FIG. 4 is a diagram showing a macroblock of one main image screen according to the embodiment of the present invention.

FIG. 5 is a diagram showing an example of a track format in the embodiment of the present invention.

FIG. 6 is a block diagram of a second embodiment of the recording / reproducing system.

FIG. 7 is a block diagram showing an example of a video signal recording / reproducing system in a conventional digital VTR.

FIG. 8 is a diagram showing a blocking operation in a conventional digital VTR.

FIG. 9 is a diagram showing a macroblock of one frame in a conventional digital VTR.

FIG. 10 is a diagram showing a track format in a conventional digital VTR.

FIG. 11 is a diagram showing an image from a PALplus source to a receiver.

FIG. 12 is a block diagram illustrating a PALplus encoder and decoder.

[Explanation of symbols]

11, 25 ... A / D converter, 12 ... blocking circuit,
13 DCT circuit, 14 encoder, 15 framing circuit, 26 memory, 31 boost amplifier, 43
… Helper signal demodulator

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/91-5/956 H04N 9/79-9/898

Claims (2)

(57) [Claims] (A) first means for demodulating a helper signal from a PALplus television signal;
(B) second means for converting the helper signal demodulated by the first means into uncompressed digital data, and (c) a main image signal separated from the PALplus television signal, which is compressed. (D) means for recording the output of the second means and the output of the third means in another area of a recording medium. Signal recording / reproducing device. 2. (a) first means for demodulating a helper signal from a PALplus television signal;
(B) second means for amplifying the helper signal demodulated by the first means, and (c) compression of the output of the second means and the main image signal separated from the PALplus television signal. A digital video signal recording / reproducing apparatus, comprising: (d) fourth means for recording output data of the third means on a recording medium.