JPS60223275A - Recording method of digital video signal - Google Patents

Abstract

PURPOSE:To attain a recording method of digital video signal with high efficiency by extracting the continuous picture frames every 2<n>-1 for recording and recordig the information on other frames by means of a differential luminance signal. CONSTITUTION:The 1st picture frame group arranged every (2<n>-1) pieces (n: natural number) are extracted out of continuous picture frames and then recorded digitally as they are. At the same time, information on the adjacent frame groups belonging to the 1st picture frame group is recorded digitally by means of the differential luminance signals shown by each equation. Thus it is possible to secure the satisfactory picture quality for practical application even with a recording medium having a small transmission rate and small capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for recording digitized video signals, and more specifically, a method for recording video signals arranged for each image frame into an image frame or a part of an image. The present invention relates to a digital video signal recording method in which the amount of information is reduced and digitally recorded by thinning out the information in units of data.

(Prior Art) In recent years, video media such as video tapes and video discs are rapidly becoming popular in response to the demands of the information society.

Conventionally, analog signals have been used to record these video media onto recording media, but in order to achieve higher quality video and audio, methods have been developed to record these video and audio onto recording media as digital signals. It has been researched recently.

When recording video and audio as digital signals, it is possible to obtain playback signals with a higher S/N ratio and lower distortion than when recording as conventional analog signals, and furthermore, wow and flutter does not exist in principle, etc. Extremely excellent properties can be obtained.

However, there are problems in that real-time recording as such digital signals requires a high transmission rate and also requires a large capacity recording medium. In particular, when video is simultaneously recorded on a compact cassette or the like where recording capacity is limited and high quality audio is required, how to efficiently record video signals has become a major issue.

(Object of the Invention) The object of the present invention has been made in view of the above circumstances, and is to provide a digital video signal recording method that can obtain practically adequate image quality using a low transmission rate and a small capacity recording medium. The purpose is to provide

(Structure of the Invention) The digital video signal recording method of the present invention extracts a first group of image frames lined up every 2'-1 (pieces) (n is a natural number, the same applies hereinafter) from consecutive image frames and records each one as is. Digitally records the information of a second image frame group arranged between adjacent image frames a to the first image frame group together with a differential luminance signal (ΔY + 2'') each represented by the following formula. It is characterized by digital recording length using .

ΔY +2~=Y! Yl + 2 mash i = 2' -m +k (+++ , k
C natural number) 'y'i: Luminance signal of the i-th image frame (first image frame group) Y juice 2'': i+2' Luminance signal of the first image frame (
(Second Image Frame Group) Here, the differential brightness signal is the difference obtained by subtracting the brightness level of the same information position of the corresponding overlapping frame from the brightness level of the same information position of the basic frame.

In addition, the above-mentioned "as is" refers to the information of the frame that has been processed out of the digital information obtained by the lean-pulling frequency and quantization number that can obtain a reproduced image with perfect image quality. It is the meaning.

The above-described configuration will be explained using a specific example of recording a television image signal. For example, an NTSC TV image consists of 30 frames per second, and it is assumed that frame numbers 1 to 30 are sequentially assigned to the image frames displayed on a cathode ray tube in any given second. In the method of the present invention, for example, the first frame a
5 and every 3 frames from this first frame (n in the above formula
(equivalent to the case where 2 is assigned to
13.1? .

. . , for each of the 29 frames (corresponding to the first image frame IY), the luminance signal and color signal of that image frame are recorded, and the 3.7th frame arranged in the middle of each of these frames is recorded. .11.15. ..., for each of the 27 frames (corresponding to the second image frame group), the differential luminance signal (for example, for the third frame, the difference between the luminance signal of the first frame and the R intensity signal of the third frame) is calculated. This is recorded as image frame information.

(Effect of the invention) According to the digital video signal recording method of the present invention, the second
Since the information of the image frame group 8Y is recorded as a differential luminance signal with respect to the first image frame group, the transmission rate and storage medium capacity required for the information of the second image frame 8Y can be significantly reduced. be able to. Furthermore, even if the number of quantizations in the second image frame group is set to about half of the number of m children in the first image frame group, practically no significant deterioration in image quality is observed.

Furthermore, when each differential luminance signal is decoded, luminance signal information of the image frame belonging to the first image frame group used when taking the difference is added, and color signal information is further superimposed. Accordingly, it is possible to reproduce an image frame that is substantially the same as the image frame before being recorded.

Therefore, according to the method of the present invention, high-quality reproduced images with a large number of frames per unit time can be obtained using a low transmission rate and a small-capacity recording medium.

(Embodiment) The following describes the implementation of the digital video signal recording method of the present invention.
7I aspect in detail.

First, digital recording using the method of the first embodiment
A simple block diagram of the playback system is shown in Figure 1. In this embodiment, digital recording and reproduction of audio signals as well as video signals are performed, and a so-called cassette tape or the like is used as the recording medium. , audio and video analog signals are input to an encoding digital processing unit 1 such as a deck. This processing unit 1 performs information source encoding (sampling,
quantization, encoding) and transmission path encoding (correction code addition,
(modulation, etc.) and is recorded on the recording medium 2 through the recording head.

When a signal recorded on the recording medium 2 is reproduced, the recorded information is transmitted to the decoding digital processing section 3 through a reproduction head such as a deck. This processing section 3
The signal is subjected to transmission path decoding (demodulation, error correction) and information source decoding (DA conversion, interpolation) processing, and analog audio and video signals are output to the outside.

In the first embodiment of the present invention, the encoding digital processing unit 1 forms information blocks 4 of a certain capacity as shown in FIG. It is now recorded in In addition, when playing back, each block 4 is input to the decoding digital processing unit 3 in chronological order and decoded.

Block 4 shown in FIG. 2 consists of an 8-bit synchronization signal area, 5, 40-bit differential video signal area, 6, 8-bit address and identification code area, 7.64-bit Y signal area, and 8.16-bit Y signal area. I signal area of 9.8 bits Q(3
code area 10.32-bit audio signal area 11.3
2-bit parity area 12 and 16-bit CR
It consists of a C (cyclic code) check code area 13. Here, areas 8, 9, and 10 are used for video signals, that is, luminance signals (Y signals) and color signals (I signals, Q signals), and audio signal areas 11 are used for audio signals. Further, the differential video signal area 6 has a configuration as shown in FIG. That is, area 6 consists of an 8-bit preliminary code area, 14 bits, and a 32-bit Y' signal area 15.

Note that the YLL signal area 16 is not used here.

A specific example in which consecutive image frames are allocated to the above-mentioned block 4 and recorded will be described below.

Four consecutive image frames are considered as one unit, and frame numbers 0.1 and 2.3 are assigned in order. At this time, the Y, I, and Q signals of the first frame (Yo.

The 1o and Qo multiplied signals are accommodated in the Y signal area 8, the ■signal area 9, and the Q signal area 1° of block 4 in FIG. 2, respectively. Next, the Y signal (Y2 signal) of the second frame is
It is accommodated in the Y' signal area 15 of the differential video signal area 6 in the figure. Here, the Y' signal area contains information obtained by compressing the quantization number to 1/2 and digitizing the differential luminance level of ΔY2=YOY2. Next, for the first frame and the third frame, the difference signals obtained by subtracting each Y signal (Y1 signal and Y3 signal) from the Yo-fold signal or Y2 signal, that is, the YOYL-fold signal and the Y2 Y3 signal, are calculated as quantum signals. The digital signal is compressed into 174 basic frames and converted into a digital signal, which is used as a selected video signal.

When the sampling frequency of the audio signal is 48KH11, the number of bits is 16 bits, and the number of channels is 2 channel stereo, the above-mentioned selected video signal is not recorded.

For audiovisual sources where the video signal changes rapidly and the quality of the audio signal may be lowered, the sampling frequency of the audio signal should be set to 32K Hz.
, the number of ffi children is 12 bits, the number of channels is 1 channel monaural, and the audio signal area 11 is 32 bits.
Of the bits, 8 bits are used to record the audio signal.

The remaining 24 bits of area 11 and 8 of pre-value code area 14
The bits are used to record the selected video signal.

At this time, a flag (identification code) is set in region [7.

Furthermore, the parity area 12 is an area used for parity added to the sampled word for error detection and correction in order to avoid quality deterioration of the reproduced signal due to code errors caused by various factors in the signal transmission process.

In addition, CRCIaU [13] is also a CR for error detection and correction.
This is the area used for the C signal.

Note that the sampling frequency and quantization number of each signal in the embodiment described above are listed in Table 1.

The blocks 4 as described above are sequentially recorded on the recording medium 2 through the recording head.

Track pattern 1 when such blocks 4 are recorded chronologically on a digital magnetic tape by a deck.
9 is shown in FIG.

The tape 20 shown in FIG. 4 has a width (A>3.78tttm
The track pattern 19 in the figure was recorded by winding the tape at about 90 degrees around a drum with a diameter of 30IIIR inside a deck, and using two rotary heads facing each other at a rotation speed of 120 rps. The chip running speed (Vt) is 27.776 rttm/sec, the writing speed (Vh) is 2.8207 yL/sea, the effective recording width (w) is 2.98 m, and the track angle (θ) is 6.9.
°, the track length (L) is set to 23.5 mm, and the track pitch (P) is set to 14.0'um. Each track pattern 19 has 8 blocks of clock run-in (
Clock Run-1n), 200 block data area and 2 block postamble (Pos
, t A ble), and 200 blocks as shown in FIG. 2 are captured and recorded in the data area.

When the audio and video information recorded on such a digital magnetic tape 20 is played back, it is read by the playback head of the deck, and the read signal is input to the decoding digital processing unit 3, and the image frame is Processing (decompounding) that is the opposite of the processing (compounding) that accommodates each signal in the block 4 is performed, demodulation and error correction processing are performed, and D-A conversion and interpolation are performed for each audio and video signal. The signals are processed and output as analog audio signals and analog video signals to the outside.

Note that the superposition of the ■ signal, the Q signal, and the Y signal in the above-mentioned decompounding process will be explained using the above-mentioned specific example.

That is, for the second frame in the specific example, the respective I and Q signals recorded in block 4 are used as they are. For the second frame,
The Y2 signal decoded from Yo and Y' is superimposed with the Io and Qo times signals. For the 1st and 3rd frames, if the flag is not set in area 7, the 0.2nd Y, 1 . Q
Use signals. When territory 1iX7 is flagged,
a Y1 signal decoded from the YO multiplied signal and the selected video signal;
To the Y3 signal decoded from the Y2 signal and the selected video signal,
The video signal is reproduced by superimposing Io and Qo times the signals.

According to the first embodiment described above, when recording continuous image frames, the image frames are extracted every three or every other frame, and the Y signal, ■ signal, and Q signal are used as information blocks. For the remaining image frames, the differential luminance signal is stored and recorded in the information block 4, so that all the image frames to be reproduced are Y.

1. Compared to the conventional method of recording Q signals, images with comparable quality can be reproduced using a smaller capacity recording medium and a lower transmission rate. Note that the information-bit transmission rate in this actual M mode is 7.296 M BPS, which is much lower than in the conventional method.

Although the embodiment described above uses a so-called compact cassette system, the present invention is not limited to using a compact cassette tape as a recording medium, and various tapes can be used. For example, so-called V)-18 cassette tapes can also be used. A third embodiment in which compounding is performed every other frame using this VHS cassette tape will be shown below.

This second embodiment has substantially the same processing steps as the first embodiment described above, but differs in sampling frequency, quantization number, block number, etc.

That is, the sampling frequency and quantization number used in the second embodiment are as shown in Table 2.

Block 4 in the second embodiment has an 8-bit synchronization signal/signal area [5, 32-bit differential video signal area 6, 8-bit address code area 7, 64-bit Y signal area 8... 1 signal area of 16 bits 9. Q signal area of 8 bits 10. Audio signal area of 8 bits 11.
32-bit parity area 12 and 16-bit C
It consists of an RC (cyclic code) check code area 13. Furthermore, the area 11i6 is a 32-bit Y' signal area 15.
It's roaring.

Furthermore, the tape 20 on which this block 4 is recorded has a width (
A > 12.65 am, 1 track length (-
L) is 96.9#l#l, and 800 blocks 4 are recorded on one track.

Note that in the two embodiments described above, the information block 4 has the area configuration as explained above, but the capacity of each area is not necessarily limited to the numerical value as explained above. Depending on the application, the capacity may be determined so that, for example, the video signal area 6,8°9,10 is larger and the audio signal area 11 is smaller.

Further, in the embodiment described above, the magnetic tape 20 is used as the recording medium 2, but the recording medium 2 is not limited to this, and for example, a magnetic disk,
Optical discs such as compact discs (CDs), magneto-optical tapes, magneto-optical discs, etc. may also be used.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the flow of signals in a digital recording and reproducing system using the digital video signal recording method according to an embodiment of the present invention, and FIG. 2 shows information blocks used in the actual M embodiment of FIG. Figure 3 is an enlarged diagram of a part of Figure 2, and Figure 4 is a block diagram showing information on the magnetic tape when the information related to the blocks in Figure 2 is recorded on the magnetic tape in chronological order. FIG. 1 is a schematic diagram showing 1 to easy patterns. 1... Encoding digital processing section 2... Recording medium 3... Decoding digital processing section 4... Information block 6... Differential video signal area 7
...Address code area 8...Y signal area 9...I signal area 10...Q
Signal area 11...Audio signal area (voluntary) procedure 1n Author: Mr. Commissioner of the Patent Office June 11, 1981 2. Title of invention Digital video signal recording method 3. Relationship with amended person case Patent Applicant Address: 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Name: Fuji Photo Film Co., Ltd. 4, Agent: 5-2-1-6 Roppongi, Minato-ku, Tokyo Number of inventions increased by amendment: None 7: Subject of amendment Column 8 of "Detailed Description of the Invention" of the Specification, Contents of Amendment 1) Book III, page 13, line 14, ``Pizza'' is corrected to ``Bitsuji''.

Claims (1)

[Scope of Claim] A digital video signal recording method for recording image information of successive image frames as a digitized video signal, comprising 2n1 image frames (n is a natural number).
At the same time, the information of the 21st image frame from each image frame to be recorded is expressed as a differential signal (ΔY +
2"') ΔYl+2 - Yi - Y++ 4 where i = 2' -m +k (m, k 4.
(selfPAR) Yi: Luminance signal Y of the i-th image frame
1+2"": A digital video signal recording method characterized in that digital recording is performed using the luminance signal of the f+2 p-th image frame.