JPH04230184A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain dubbing while minimizing deterioration in a picture data by sending a specific control signal and a specific coefficient signal together with a picture signal. CONSTITUTION:A picture signal, a control signal representing whether or not the picture signal has been subject to high efficient coding and decoding processing in the past and a coefficient signal representing a coefficient at that time when the processing is implemented in the past are recorded on a magnetic tape. In the case of recording a picture signal reproduced by a VTR 23 at a VTR 24, the VTR 23 supplies the control signal, the coefficient signal to the VTR 24 together with the picture signal. When the VTR 24 discriminates it that the picture signal has been subject to high efficient coding and decoding processing in the past based on the content of the control signal, the VTR 24 applies high efficient coding processing to the inputted picture signal based on the coefficient commanded by the coefficient signal and records the result onto the magnetic tape.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a recording and reproducing apparatus that highly efficiently encodes an effective transmission information signal such as digital image data, records it on a recording medium, and decodes and reproduces it at the time of reproduction. The present invention relates to a method for preventing data deterioration due to high-efficiency encoding during so-called double recording (hereinafter referred to as dubbing) in which an information signal reproduced from a medium is recorded on another recording medium.

0002

2. Description of the Related Art As is well known, the standardization of high-efficiency encoding of digital data is being actively promoted.
Experts Group), CD (Compa
ct Disc)-ROM(Read OnlyM
MPEG (Mov) for storage media such as
ing Picture Experts Gr.
oup) [Nikkei Electronics 19
90.10.15 (No.511) P. 124-P. 1
29]. On the other hand, digital recording and reproducing apparatuses that record highly efficiently encoded signals on a recording medium, read the signals from the recording medium, decode the signals, and reproduce the signals are also being developed. As this digital recording and reproducing device, a digital VT using magnetic tape as a recording medium is used.
BACKGROUND ART R (video tape recorders) and IC (integrated circuit) memory devices using semiconductor memory have been developed.

[0003] Here, the above-mentioned high-efficiency encoding is based on DCT (D
iscrete Cosine Transfer
Currently, the method using an orthogonal transformation system called m) is the mainstream. FIG. 5 shows a conventional high-efficiency encoding means using this DCT. That is, numeral 11 in the figure is an input terminal, to which digital image data is supplied as an effective transmission information signal. This digital image data is
Taking the C method as an example, first, two fields of image data transmitted in field sequence are stored in a memory (not shown) to create one frame of digital image data. In this case, the digital image data includes luminance signals Y,
It is a decoded form of the red component Cr and blue component Cb of the color signal, and hereinafter, unless otherwise specified, the luminance signal Y
will be explained using an example.

[0004] When the digital image data converted into a frame is sampled at 4fSC (14.3 MHz), for example, 910 samples are sampled in one horizontal line, so the number of pixels is 910. Moreover, in the vertical direction, the number of pixels is 525 for 1, which is 525 lines, and in the end, the number of pixels at the time of sampling is 910×525. However, since the effective portion visible on the screen is about 80% (768×488), this portion becomes the digital image data supplied to the input terminal 11 as an effective transmission information signal. Further, this digital image data is supplied to the input terminal 11 in blocks of, for example, 4 pixels x 4 pixels.

[0005] Then, the digital image data supplied to the input terminal 11 is supplied to the DCT circuit 12 and orthogonally transformed for each block. This orthogonal transformation converts digital image data into a frequency axis block by block, and creates high frequency components (AC components) in order from low frequency components (DC components) two-dimensionally in both the horizontal and vertical directions. In order to correspond to the zigzag scan shown by the arrow in FIG. 6, as the arrow advances in the horizontal and vertical directions,
The arrangement changes from direct current to low frequency to high frequency. The data thus orthogonally transformed is delayed by the frame delay circuit 13 by one frame's time corresponding to the calculation time by the activity calculation circuit 21 (described later), and then supplied to the scan conversion circuit 14.

The scan conversion circuit 14 scans the data of the block in a zigzag manner as shown by the arrows in FIG. It rearranges the frequency components one-dimensionally and outputs them. The reason for this is that when reducing the bit rate, in order to faithfully reproduce the original image, it is possible to reproduce a visually better image by sequentially transmitting higher frequency components starting with the DC component. be. The data scan-converted in this manner generally has a larger amount of data than the original digital image data, and cannot be compressed as it is, so it is supplied to the quantization circuit 16 for requantization.

The quantization circuit 16 calculates the amount of data by dividing the scan-converted data by the result of multiplying the contents recorded in the basic quantization table 17 by a coefficient a, which will be described later, by the multiplication circuit 18. We are making reductions. The data requantized by the quantization circuit 16 is further supplied to the variable length encoding circuit 19, where it is efficiently transmitted encoded. That is, Huffman encoding is most often used for encoding by the variable length encoding circuit 19, in which consecutive numbers of "0" of the requantized output are combined with a number other than "0" that follows. The number of bits is allocated in descending order of the probability of occurrence, reaching a minimum of 2 bits and a maximum of several tens of bits, where data compression of digital image data is performed and output terminal 20
The image data is then taken out and recorded on a recording medium (not shown).

[0008] Here, in order to compress data while maintaining image quality, requantization processing by the quantization circuit 16 is most important, but what determines its performance is the basic quantization table 17 and the input This calculation is for calculating the coefficient a to be multiplied by the basic quantization table 17 according to the digital image data. This calculation uses the high definition of the image (the fineness of the image and the proportion of high frequency components included). That is, the calculation of the coefficient a is performed by supplying the output of the DCT circuit 12 to the activity calculating circuit 21, using the high frequency component of the output, and using the standard deviation or the amount extracted by a specific filter as an evaluation measure. The calculation result is then supplied to the coefficient conversion circuit 22, converted into a coefficient a, and supplied to the multiplication circuit 18.

[0009] When reproducing a recording medium on which highly efficiently encoded data is recorded as described above, the variable length encoded data is read from the recording medium and is processed in the reverse process to that for encoding. , inverse quantization, inverse scan conversion, and inverse DCT processing to reproduce the original digital image data and provide it for image display.

However, in the conventional high-efficiency encoding means using DCT as described above, the following problems occur. That is, let us now consider how to highly efficiently encode the original image signal to be recorded on the first recording medium. At this time, from the scan conversion circuit 14 to the quantization circuit 1
Assume that the input to 6 is as shown in FIG. 7(a), the basic quantization table 17 is as shown in FIG. 7(b), and the coefficient a at this time is "2". Then, the quantization circuit 16 assigns a coefficient “2” to each value of the basic quantization table 17.
The corresponding quantization circuit 1 is multiplied by each multiplication result.
Since each value of the 6 inputs is divided, the output of the quantization circuit 16 has the original data amount reduced, as shown in FIG. 7(c). Then, as shown in FIG. 7(c), the compressed data is subjected to variable length encoding processing and recorded on the first recording medium.

By the way, when this first recording medium is reproduced, each value of the basic quantization table 17 has a compression coefficient "
The data is decompressed by multiplying each compressed value by 2'' and inverse quantization by multiplying each multiplication result by each compressed value as shown in FIG. 7(c). In this case,
The inverse quantization result is indicated by × in the figure as shown in Fig. 7(d).
The marked portion is the portion where the data does not return to the original value shown in FIG. 7(a) and deteriorates. However, this D
Since high-efficiency encoding using CT is an irreversible encoding method, the above-mentioned data deterioration is unavoidable and is not a problem to be solved by the present invention.

The problem to be solved by the present invention is that which occurs when data recorded on a first recording medium is reproduced and recorded on a second recording medium as described above, so-called dubbing. It is. That is, considering that the output shown in FIG. 7(d), which is the dequantized reproduction data of the first recording medium, is further subjected to high-efficiency encoding processing and recorded on the second recording medium, The apparatus that records data on the recording medium calculates the coefficient a based on the degraded data shown in FIG. Suppose it becomes .8”. Then, on the device side that records data on the second recording medium, each value of the basic quantization table 17 shown in FIG. 7(b) is multiplied by a coefficient "1.8", and the corresponding diagram is Since each value shown in 7(d) is divided, the result is shown in FIG. 8(a), and the data compressed as shown in FIG. 8(a) has been subjected to variable length encoding processing. Second
used for recording on recording media.

When this second recording medium is reproduced, the apparatus multiplies each value of the basic quantization table 17 by the compression coefficient "1.8", and the multiplication results are shown in FIG. As shown in (a), data is expanded by performing inverse quantization by multiplying each compressed value. In this case, the dequantized result will be as shown in Figure 8(b), and all parts in the figure will not return to the original values shown in Figure 7(d), resulting in significant data deterioration. Different. When data recorded on this second recording medium is reproduced and further dubbed onto a third recording medium, even greater data deterioration occurs.

That is, digital data is subjected to high-efficiency encoding processing and recorded on a recording medium, the data is read from the recording medium and decoded, and the data is again subjected to high-efficiency encoding processing and recorded on another recording medium. When recording, a problem arises in that the more the number of times dubbing is performed, the greater the data deterioration due to the use of high-efficiency encoding/decoding, which is an irreversible encoding method.

[0015]

[Problems to be Solved by the Invention] As described above, conventional recording and reproducing devices that use high-efficiency encoding and decoding reproduce data that has been recorded on a recording medium by performing high-efficiency encoding processing. When performing high-efficiency encoding processing on data and recording it on another recording medium, there is a problem in that the data deteriorates more as the number of times it is encoded increases.

The present invention has been made in consideration of the above circumstances, and it is possible to minimize data deterioration when an information signal is encoded with high efficiency, recorded on a recording medium, and decoded during playback. It is an object of the present invention to provide an extremely good recording/reproducing device particularly suitable for dubbing.

[0017]

[Means for Solving the Problems] A recording/reproducing device according to the present invention records an information signal on a recording medium by performing high-efficiency encoding processing, and also subjects a signal read from the recording medium to the high-efficiency encoding processing. It is intended for those that perform corresponding decoding processing and playback.

[0018] The information signal to be recorded on the recording medium, the control signal indicating whether or not this information signal has been subjected to high-efficiency encoding and decoding processing in the past, and the information signal to be recorded on the recording medium are If the information signal has been subjected to high-efficiency encoding and decoding processing, a coefficient signal indicating the coefficients used in the high-efficiency encoding and decoding processing at that time is supplied, and the information signal has been subjected to high-efficiency encoding and decoding processing in the past. If the information signal has not been subjected to decoding processing, the information signal is subjected to high-efficiency encoding processing based on coefficients generated by itself based on the information signal, and the coefficient signal indicating the generated coefficient and the information signal are If the information signal is recorded on a recording medium together with a control signal indicating that the information signal has been subjected to high-efficiency encoding and decoding processing in the past, a recording means that performs high-efficiency encoding processing on an information signal based on a coefficient indicated by the coefficient signal and records it on a recording medium together with the coefficient signal and a control signal; and a recording means that reads the information signal, the control signal and the coefficient signal from the recording medium, The apparatus includes a reproduction means for decoding a signal based on the coefficients indicated by the coefficient signal and outputting the read control signal and coefficient signal to the outside.

[0019]

[Operation] According to the above configuration, in addition to the information signal, a control signal indicating whether or not the information signal has been subjected to high-efficiency encoding and decoding processing in the past, and a control signal indicating whether the information signal has been subjected to high-efficiency encoding and decoding processing in the past. When undergoing efficiency encoding and decoding processing, a coefficient signal indicating the coefficient at that time is recorded together on a recording medium, and the information signal obtained by reproducing the recording medium is transferred to another recording medium. When recording on a medium, if the reproduced information signal has not undergone high-efficiency encoding and decoding processing in the past, the recording device performs high-efficiency encoding processing using coefficients it generates on its own based on the information signal to be recorded. and record a coefficient signal indicating the coefficient and a control signal indicating that the information signal recorded on the recording medium has undergone high-efficiency encoding and decoding processing in the past together with the information signal, and If the reproduced image signal has undergone high-efficiency encoding and decoding processing in the past, high-efficiency encoding processing is performed based on the coefficients indicated by the reproduced coefficient signal, and the coefficient signal and information indicating the coefficients are processed. Since the reproduced control signal indicating that the signal has undergone high-efficiency encoding and decoding processing in the past is recorded on the recording medium together with the information signal, When the received information signal is encoded with high efficiency, recorded on a recording medium, and decoded during playback, deterioration of the information signal can be minimized, making it particularly suitable for dubbing.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before explaining one embodiment of the present invention, the principle of the present invention will be explained below. That is, in the conventional explanation described above, when recording the decoded data on the second recording medium as shown in FIG. 7(d), the coefficient "1.8" calculated based on this data is Since the coefficient "1.8" was used to requantize the data, the quantized output is as shown in FIG. Deterioration will occur. However, as shown in FIG. 7(d) above, when recording the decoded data on the second recording medium, if the coefficient "2" used when decoding the data is requantized, The basic quantization table 17 shown in FIG. 7(b) has a coefficient “2”.
Since each value shown in FIG. 7(d) is divided by the value multiplied by ", the requantization result will be as shown in FIG. 4(a) and recorded on the second recording medium. served.

Here, the requantization result shown in FIG. 4(a) is, of course, the requantization result when the original image signal shown in FIG. 7(c) is recorded on the first recording medium. It will be equivalent to the quantization result. Therefore, if the above coefficient "2" is used when dequantizing the data obtained by reproducing the second recording medium, the dequantization result will be as shown in FIG. 7(b).
It will be equivalent to that shown in d). Therefore, from now on, if high-efficiency encoding and decoding are performed using the coefficient "2" at the time of requantization when the original image signal is recorded on the first recording medium, dubbing can be repeated several times. However, as long as the basic quantization table 17 remains unchanged, no data deterioration will occur due to high-efficiency encoding and decoding.

[0022] Hereinafter, an embodiment of the present invention based on the above principle will be described. Here, a helical scan type VTR using magnetic tape will be described as a device for recording and reproducing digital image data. That is, as shown in FIG. 1, when two VTRs 23 and 24 each having high-efficiency encoding and decoding functions are prepared, and an image signal reproduced by the VTR 23 is recorded on the VTR 24, effective transmission from the VTR 23 to the VTR 24 is possible. In addition to the image signal as an information signal, there is also a control signal indicating whether or not the image signal to be transmitted has undergone high-efficiency encoding and decoding processing in the past, and a control signal indicating whether or not the image signal to be transmitted has undergone high-efficiency encoding and decoding processing in the past. When undergoing encoding and decoding processing, a coefficient signal indicating the coefficient A1 at that time is also transmitted.

In this case, the control signal and coefficient signal are as follows:
The control signal and coefficient signal are recorded on a magnetic tape (not shown) along with the image signal, and by reproducing this magnetic tape on the VTR 23, the control signal and coefficient signal are recorded on the VTR 24 along with the image signal.
It is designed to be supplied to And VTR24
Then, when it is determined from the content of the control signal that the input image signal has not been subjected to high-efficiency encoding and decoding processing in the past, the coefficient A is automatically calculated based on the input image signal.
2 is calculated, and based on the coefficient A2, the image signal is subjected to high-efficiency encoding processing and recorded on a magnetic tape. Further, when it is determined from the content of the control signal that the input image signal has been subjected to high-efficiency encoding and decoding processing in the past, the VTR 24 inputs the input image signal according to the coefficient signal. High-efficiency encoding processing is performed based on the coefficient A1, and the data is recorded on a magnetic tape.

FIG. 2 shows the detailed configuration of the VTR 24. Regarding VTR23, VTR2
Since the configuration is similar to that of 4, the explanation thereof will be omitted. That is, the VTR 24 is composed of a data recording system 25 and a data reproducing system 26. Of these, the data recording system 25 has an image signal input terminal 25a to which an image signal is supplied from the outside, a control signal input terminal 25b to which a control signal is supplied from the outside, and a coefficient signal input terminal to which a coefficient signal is supplied from the outside. It has a terminal 25c. The analog image signal supplied to the image signal input terminal 25a is
After predetermined image signal processing is performed by the image signal processing circuit 25d, the A/D (analog/digital) conversion circuit 2
5e, the data is converted into digital image data and supplied to a high-efficiency encoding circuit 25f.

Further, the control signal supplied to the control signal input terminal 25b is received by the receiving circuit 25g, and then supplied to the high efficiency encoding circuit 25f. Further, the coefficient signal supplied to the coefficient signal input terminal 25c is received by the receiving circuit 25h and then sent to the high efficiency encoding circuit 25.
f. This high efficiency encoding circuit 25f
Then, the input digital image data is subjected to high-efficiency encoding based on the control signal and the coefficient signal, and is output to the image data processing circuit 25i. The image data processing circuit 25i performs parity addition processing for error correction, predetermined interleaving processing, etc. on the input digital image data, and outputs the data to the addition circuit 25j. Further, the high efficiency encoding circuit 25f outputs the input control signal and coefficient signal, and these control signals and coefficient signals are delayed by the processing time by the image data processing circuit 25i by the delay circuits 25k and 251, respectively. After that, it is supplied to the adding circuit 25j and added to the digital image data. Then, the digital image data accompanied by the control signal and the coefficient signal output from the adder circuit 25j is modulated by a modulation circuit 25m, amplified by a recording amplification circuit 25n, and then sent to a magnetic field (not shown) via a recording head 25o. Recorded on tape using the helical scan method.

On the other hand, the data reproducing system 26 has a reproducing head 26a that traces the magnetic tape and reads recorded signals thereof. And this playback head 26a
The recorded signal read in is amplified by a reproduction amplification circuit 25b, demodulated by a demodulation circuit 26c, and separated into digital image data, a control signal, and a coefficient signal. Of these, the digital image data is supplied to the image data processing circuit 26d, subjected to error correction processing and deinterleaving processing, and then supplied to the decoding circuit 26e. Further, the control signal and the coefficient signal are delayed by the processing time of the image data processing circuit 26d by the delay circuits 26f and 26g, respectively, and then supplied to the decoding circuit 26e. Decryption is performed.

The digital image data output from the decoding circuit 26e is converted into an analog image signal by a D/A (digital/analog) conversion circuit 26h, and converted into a predetermined image signal by an image signal processing circuit 26i. After being processed, it is taken out from the image signal output terminal 26j. Further, the decoding circuit 26e outputs a control signal and a coefficient signal, and these control signals and coefficient signals are taken out from a control signal output terminal 26m and a coefficient signal output terminal 26n via transmission circuits 26k and 261, respectively. It will be done.

Here, FIG. 3 shows the above-mentioned high-efficiency encoding circuit 2.
5f is shown in detail, and the same parts as in FIG. 5 are given the same reference numerals. That is, the coefficient A2 output from the coefficient conversion circuit 22 is the first fixed contact 2 of the switch circuit 27.
7a. A coefficient A1 based on the coefficient signal output from the receiving circuit 25h is supplied to the second fixed contact 27b of the switch circuit 27 via an input terminal 28. The coefficient A1 or A2 selected by this switch circuit 27 is supplied to the multiplication circuit 18 via the common contact 27c, and is also supplied to the delay circuit 251 via the output terminal 29.

Further, the switch circuit 27 is switched and controlled by a switching signal outputted from the control circuit 30. This control circuit 30 generates a switching signal by receiving a control signal outputted from the receiving circuit 25g via an input terminal 31, and generates a switching signal from the image signal input terminal 25g.
If the image signal input to 5a is a control signal indicating that it has not been subjected to high-efficiency encoding and decoding processing in the past, the switch circuit 27 is caused to select coefficient A2, and the image input to the image signal input terminal 25a is If the signal is a control signal indicating that it has undergone high-efficiency encoding and decoding processing in the past, the switch circuit 27 is caused to select coefficient A1. Further, when a switching designation signal based on a user's operation is supplied via the input terminal 32, this control circuit 30 controls the switch circuit 27 as specified by the switching designation signal, giving priority to the control signal. It is something.

Furthermore, if the input control signal indicates that it has not been subjected to high-efficiency encoding and decoding processing in the past, the control circuit 30 determines that the input control signal has not been subjected to high-efficiency encoding and decoding processing in the past. The control signal is outputted to the delay circuit 25k via the output terminal 33 instead of the control signal with the content that the inputted control signal has been subjected to high efficiency encoding and decoding processing in the past. In some cases, it functions to output the control signal as it is to the delay circuit 25k via the output terminal 33.

Therefore, according to the configuration of the above embodiment, when an image signal reproduced by the VTR 23 is recorded on the VTR 24, in addition to the image signal, the transmitted image signal is A control signal indicating whether or not the image signal to be transmitted has been subjected to high efficiency encoding and decoding processing, and a coefficient signal indicating the coefficient A2 at that time if the image signal to be transmitted has been subjected to high efficiency encoding and decoding processing in the past. If the transmitted image signal has not been subjected to high-efficiency encoding and decoding processing in the past, the VTR 24 performs high-efficiency encoding processing based on the coefficient A2 generated by itself. A coefficient signal indicating the coefficient A2 and a control signal indicating that the image signal recorded on the magnetic tape has been subjected to high-efficiency encoding and decoding processing in the past are recorded on the magnetic tape together with the digital image data, If the transmitted image signal has undergone high-efficiency encoding and decoding processing in the past, the coefficient signal indicating the coefficient A1 that is subjected to high-efficiency encoding processing based on the input coefficient A1 and the image signal Since the input control signal indicating that the data has been subjected to high-efficiency encoding and decoding processing is recorded on the magnetic tape along with the digital image data, it is possible to When digital image data is encoded with high efficiency and recorded on a magnetic tape and decoded during playback, deterioration of the digital image data can be minimized, making it particularly suitable for dubbing.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without departing from the scope of the invention.

[0033]

[Effects of the Invention] As detailed above, according to the present invention,
To provide an extremely good recording and reproducing device which can minimize data deterioration when an information signal is encoded with high efficiency, recorded on a recording medium, and decoded during reproduction, and is particularly suitable for dubbing. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a recording/reproducing apparatus according to the present invention.

FIG. 2 is a block diagram specifically showing the same embodiment.

FIG. 3 is a block configuration diagram specifically showing main parts of the embodiment.

FIG. 4 is a diagram shown to explain the principle of the invention.

FIG. 5 is a block diagram showing a conventional high-efficiency encoding means.

FIG. 6 is a diagram shown to explain a zigzag scan.

FIG. 7 is a diagram shown to explain data deterioration due to high-efficiency encoding and decoding.

FIG. 8 is a diagram shown to explain data deterioration due to high-efficiency encoding and decoding.

[Explanation of symbols]

11... Input terminal, 12... DCT circuit, 13... Frame delay circuit, 14... Scan conversion circuit, 15... Standard scan table, 16... Quantization circuit, 17... Basic quantization table, 18... Multiplication circuit, 19... Variable length Encoding circuit, 20...
Output terminal, 21...activity calculation circuit, 22...coefficient conversion circuit, 23, 24...VTR, 25...data recording system,
26...Data reproduction system, 27...Switch circuit, 28...Input terminal, 29...Output terminal, 30...Control circuit, 31, 32...
Input terminal, 33...output terminal.

Claims (1)

[Claims] 1. A recording and reproducing apparatus that performs high-efficiency encoding processing on an information signal and records it on a recording medium, and also performs decoding processing on a signal read from the recording medium in accordance with the high-efficiency encoding processing and reproduces the signal. , an information signal to be recorded on the recording medium, a control signal indicating whether or not this information signal has been subjected to high-efficiency encoding and decoding processing in the past; If the information signal has been subjected to encoding and decoding processing, a coefficient signal indicating the coefficients used in the high-efficiency encoding and decoding processing at that time is supplied, and the information signal has been subjected to high-efficiency encoding and decoding processing in the past. If the information signal has not been decoded, the information signal is subjected to high-efficiency encoding processing based on the coefficients generated by itself based on the information signal, and the coefficient signal indicating the generated coefficient and the information signal are recorded on the recording medium together with a control signal indicating that the information signal has been subjected to high-efficiency encoding and decoding processing in the past; In this case, recording means performs high-efficiency encoding processing on the information signal based on a coefficient indicated by the coefficient signal, and records the information signal and the control signal on the recording medium together with the coefficient signal and the control signal; and a reproducing means for reading a coefficient signal, decoding the information signal based on the coefficient indicated by the coefficient signal, and outputting the read control signal and the coefficient signal to the outside together. Recording/playback device.