JPH05304664A - High efficient encoding device and video information recording and reproducing device - Google Patents

Abstract

PURPOSE:To reduce the scale of a hardware by preparing an intrafield in which a movement compensation is not operated for every (n) field, and operating a movement compensation prediction with the intrafield in the other fields. CONSTITUTION:When an error power is less than an original picture alternating current power, the first switch circuit 7 outputs a predictive mode signal, and when the original picture power is less than the error power, the circuit 7 outputs an intrand mode signal. That is, the circuit 7 outputs an input block or an error block as an encoded block based on the mode signal decided by a discriminating circuit 6. At that time, when the input block is the intrafield, the circuit 7 necessarily outputs the input block as the encoded block. The encoded block is inputted to a DCT circuit 8, converted into DCT coefficients, quantized into the prescribed number of bits by a quantizing circuit 9, the quantized DCT coefficients are converted into codes suited to a transmission path 11 by a first encoding circuit 10, and outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal recording / reproducing apparatus such as a video tape recorder (hereinafter abbreviated as VTR) for digitally recording and reproducing a video signal and an audio signal, a video disc player, an audio tape recorder and the like. In particular, the present invention relates to a device for compressing and coding a video signal by performing motion compensation prediction.

[0002]

2. Description of the Related Art In a consumer digital VTR, data compression is indispensable in view of cost and hardware scale. Therefore, data compression will be described mainly using a consumer digital VTR as an example.

FIG. 1 is a simple block diagram of a consumer digital VTR. 900 is an input terminal for inputting an analog video signal such as a television signal.
901 is an A / D converter for converting an analog video signal into a digital video signal, 902 is a data compression unit for compressing the information amount of the digital video signal to reduce the information amount, and 903 is an error so that error correction can be performed at the time of reproduction. An error correction coding unit that adds a correction code, 904 is a recording modulation unit that modulates to a code suitable for recording for recording, 905 is a recording amplifier that amplifies a recording signal, and 906 is a magnetic recording and storing magnetic signal. It is a tape. Reference numeral 907 is a head amplifier that amplifies a reproduction signal reproduced from the magnetic tape 906, 908 is a reproduction demodulation unit that demodulates the reproduction signal, and 909 is an error correction decoding unit that error-corrects the reproduction reproduction signal using an error correction code. Reference numeral 910 is a data decompression unit for restoring the compressed data to the original form, 911 is a D / A converter for converting a digital video signal into an analog video signal, and 912 is an output terminal.

Next, the data compression unit (high efficiency coding device) 902 will be described. FIG. 2 shows a block diagram of a high-efficiency coding apparatus based on unidirectional motion-compensated interframe prediction. Reference numeral 1 is a digital video input terminal, 2 is a blocking circuit for blocking a digital video input signal into a block, 3 is a subtractor for outputting an error signal between an input block and a prediction block as an error block, and 4 is a power for the error block. Error power calculation circuit, 5 is an original image power calculation circuit for calculating the AC power of the input block, 6 is a determination circuit for comparing the error power with the original image AC power, and determining the prediction mode or intra mode, 7 is the determined mode A first switch circuit for selectively outputting a coding block based on the following: 8 is a discrete cosine transform (hereinafter abbreviated as DCT) which is an orthogonal transformation to the coding block.
Is a DCT circuit for performing the above, 9 is a quantization circuit for quantizing DCT coefficients, 10 is a first coding circuit for performing coding suitable for a transmission path, and 11 is a transmission path.

Reference numeral 12 is an inverse quantization circuit which inversely quantizes the quantized DCT coefficient, 13 is an inverse DCT circuit which performs inverse DCT on the inverse quantized DCT coefficient, and 14 is an output signal of the inverse DCT circuit 13. Is an adder that adds a prediction block to a decoding block to generate an output block, 15 is an image memory that stores an output block for performing motion-compensated prediction, and 16 is cut out from a past image stored in the image memory 15. An MC circuit that performs motion detection from the motion compensation search block and the current input block and performs motion compensation prediction, 17 is a MIX circuit that combines the motion vector and the mode signal determined by the discrimination circuit 6, and 18 is a MIX circuit 17 2 is a second encoding circuit for encoding the output of, and 19 is a second switch circuit for switching the prediction block according to the mode in the discrimination circuit 6. Then, by the error power calculation circuit 4, the original image power calculation circuit 5, the discrimination circuit 6, the inverse quantization circuit 12, the inverse DCT circuit 13, the adder 14, the image memory 15, the MC circuit 16, and the second switch circuit 19,
A local decoding loop 20 is constructed.

Next, the operation will be described. The input digital video signal is processed by the blocking circuit 2 regardless of whether it is an intra field for which motion compensation prediction is not performed or a prediction field (inter field) for which motion compensation prediction is performed.
[Pixel] × n [line] (m and n are positive integers) is divided into input blocks each having one unit and cut out. In the input block, the difference in pixel units from the prediction block is calculated in the subtractor 3 to obtain the error block. In this way, the input block and the error block are input to the first switch circuit 7, respectively. The error power of the error block is calculated by the error power calculation circuit 4.

On the other hand, in the input block, the AC power of the original image is calculated by the original image power calculating circuit 5. The calculated two electric powers are compared by the discriminating circuit 6, and the first switch circuit 7 is controlled so that the block with the smaller electric power is selected as the encoding target. That is, the discrimination circuit 6 outputs the prediction mode signal if the error power is smaller than the original image AC power, and conversely outputs the intra mode signal if the original image AC power is smaller than the error image power.

The first switch circuit 7 outputs the input block or the error block as a coding block based on the mode signal determined by the discrimination circuit 6. However, when the processing screen is an intra-field, all the encoded blocks to be output operate as input blocks. This switching state is shown in FIG. What is the normal mode? In the motion compensation prediction process that completes four fields as shown in Fig. 4,
In this mode, the first first field F1 of the four fields is always an intra field, and the following three second, third and fourth fields F2, F3, F4 are prediction fields.

The coding block selected by the first switch circuit 7 is converted into a DCT coefficient by the DCT circuit 8, and further the weighting process and the threshold process are performed by the quantizing circuit 9, respectively. It is quantized into a predetermined number of bits according to the coefficient of. The quantized DCT coefficient is converted into a code suitable for the transmission line 11 in the first encoding circuit 10 and output to the transmission line 11.

The quantized DCT coefficient enters the local decoding loop 20 to reconstruct an image for the next motion compensation prediction. Quantized DCT entering local decoding loop 20
The coefficient is subjected to inverse weighting processing and inverse quantization in the inverse quantization circuit 12, and further converted from the DCT coefficient into a decoding block in the inverse DCT circuit 13. The decoded block is added by the adder 14 to the prediction block pixel by pixel to restore the image. This prediction block is the same as that used in the subtractor 3. The output of the adder 14 is written in a predetermined position of the image memory 15 as an output block. Image memory 15
The required memory size depends on the prediction method. Assuming that it is composed of a plurality of field memories, the restored output block is written in a predetermined position.

From the image memory 15 to the MC circuit 16, a block which is a search range for motion detection cut out from the screen reconstructed by past output blocks is output. The size of the search range block for motion detection is i [pixel]
× j [line] (i ≧ m, j ≧ n: i, j are positive integers)
Is. Data in the search range from the image memory 15 and the input block from the blocking circuit 2 are input to the MC circuit 16 as data, and the motion vector is extracted. There are various methods for extracting a motion vector, such as a full search block matching method and a tree search block matching method, which are well known and will not be described here.

The motion vector extracted by the MC circuit 16 is
It is input to the MIX circuit 17 and is combined with the mode signal determined by the discrimination circuit 6. The combined signal is converted into a code suitable for the transmission line 11 by the second encoding circuit 18, and is output to the transmission line 11 together with the corresponding encoded block. Also M
The C circuit 16 outputs, as a prediction block, a signal that is blocked from the search range to a size (m [pixel] × n [line]) equal to that of the input block. The prediction block output from the MC circuit 16 is generated from past image information.

This prediction block is input to the second switch circuit 19 and is output from each output according to the field of the screen currently being processed and the mode signal of the decoding block. A prediction block is output from one output of the second switch circuit 19 to the subtractor 3 according to the processing field. A prediction block is output from the other output according to the mode signal of the decoding block at that time and the processing field.

As a prediction method performed in such a circuit block, for example, the one shown in FIG. 4 can be considered. In this method, an intra field is inserted every four fields and three fields in between are used as prediction fields. In FIG. 4, the first field F1 is an intra field, and the second, third and fourth fields F2, F3, F4 are prediction fields. The prediction in this method predicts the first field F1 to the second field F2 of the intra field,
Similarly, the first field F1 to the third field F3 are predicted. Then, the reconstructed second field F2 to the fourth field F4 are predicted.

First, the first field F1 is blocked in the field and DCT is performed. Further, a weighting process and a threshold process are performed and quantized, and then encoded. Further, the local decoding loop 20 decodes / reconstructs the quantized signal of the first field F1. This reconstructed image is the next second field F2, third field F3
Used for motion compensation prediction of. Second field F2
Is subjected to motion compensation prediction using the first field F1, DCT is performed on the obtained error block, and then encoded in the same manner as the first field F1.

At this time, if the AC power of the input block is smaller than the power of the error block, DCT is performed on the input block, not the error block, and the same coding as in the first field F1 is performed. Also, the second field F2 is decoded / reconstructed in the local decoding loop 20 according to the mode signal of each block, and is used for motion compensation prediction of the fourth field F4.

On the other hand, the third field F3 is also the second field
As with F2, motion compensation prediction is performed using the first field F1 and encoded. The fourth field F4 performs motion compensation prediction using the second field F2 reconstructed in the image memory 15,
It is encoded in the same manner as the third field F3. Third field
Also in F3 and the fourth field F4, if the AC power of the input block is smaller than the power of the error block, DCT is applied to the input block, not the error block, and the first field
It is encoded in the same way as F1.

For example, a consumer digital VTR as shown in FIG. 1 is expected to have high image quality and high sound quality, and for that purpose, data compression, that is, improvement of the performance of the high-efficiency encoder is essential. Therefore, the conventional prediction method as described above has the following drawbacks. In such a prediction method, since motion compensation prediction is performed using video data of one field before or one frame before, the first problem that the amount of field memory or frame memory increases and the hardware becomes large. There is.

In the prediction method of the conventional example, if a scene change occurs in units of frames, it becomes difficult to perform compression by motion compensation prediction from the reference image before the scene change when encoding the video after the scene change, and the whole code is encoded. There is a second problem that the amount increases. If the inter-field motion-compensated prediction is performed in order in the time direction as a whole, even if a scene change occurs, it is possible to suppress the increase in the code amount to a minimum, but it is possible to encode an interlaced video with little motion such as a scene change. In this case, the code amount tends to increase as a whole. Further, in the prediction method in which the third field F3 and the fourth field F4 are adaptively switched from the first field F1, the second field F2 and the third field F3 as shown in FIG.
There is a drawback that the amount of field memory or frame memory increases and the hardware becomes large.

For example, image A with a scene change in FIG.
5 shows the code amount and the S / N ratio of the luminance signal in the case where is processed by the prediction method as shown in FIG. 4 and when it is processed by the prediction method as shown in FIG. In image A, a scene change occurs in frame units. Further, the code amount and the S / N ratio of the luminance signal when the image B without scene change is processed by the prediction method of FIG. 4 and when it is processed by the prediction method of FIG. 5 are also shown. In this case, the prediction method of FIG. 5 is more advantageous for the image A having a scene change, and the prediction method of FIG. 4 is more advantageous for the image B having no scene change.

Further, in the case of performing prediction and encoding as in the conventional example, there is a third problem that the quality of the image immediately after the scene change is deteriorated when the scene change occurs in the motion compensation prediction processing process. .. .. This is because a scene change has occurred, so that motion compensated prediction that makes good use of temporal correlation cannot be performed well and the amount of information increases. The amount of information generated at this time is comparable to the amount of information equivalent to that of a normal intrafield. Then, with respect to the generated information amount, the field having this information amount is used as the prediction field, so that the information amount is compressed to the same level as the prediction field.

Therefore, the image quality of the field after the scene change is considerably deteriorated. FIG. 7 shows the transition of the information amount of a video for 5 seconds when the coding is performed by the conventional prediction method. This is so that the average for 5 seconds falls within 20 [Mbps], but there is a scene change in part A and the amount of information is increasing. The transition of the S / N ratio at that time is shown in FIG. At this time, the scene change portion is not significantly deteriorated, but the S / N ratio is deteriorated when the amount of information is reduced.

If the field is used for the next motion-compensated prediction, motion-compensated prediction of an image in which the image quality is deteriorated and the temporal correlation is reduced must be performed, and the amount of information generated again increases. .. This vicious cycle continues until the next refresh field is processed. As described above, even if the image quality is deteriorated even immediately after the scene change, the performance cannot be fully utilized in the digital image recording / reproducing apparatus that requires high image quality. For example, in a home digital VTR which is one of digital video recording / reproducing apparatuses, functions such as trick play and editing are indispensable, and in that case, remarkable deterioration of image quality becomes conspicuous.

By the way, there are VHS, β, 8 millidebio, etc. in the conventional home VCR for helicopter scan recording. Here, an 8 mm video will be described as a conventional example.
FIG. 9 is a diagram showing a tape format in the 8 mm video standard, and FIG. 10 is a diagram showing a one-track format.

FIG. 11 is a diagram showing a winding state of a rotary head drum and a magnetic tape used in 8 mm video, and FIG. 12 is a diagram showing frequency allocation of each signal in the 8 mm video standard. .. NTSC and PAL
The video signal of the 8 mm video for the system is recorded by the low frequency conversion color signal recording system, which is the basic recording system of the home VTR. The luminance signal is FM-modulated with a carrier of 4.2 to 5.4 MHz, the color subcarrier is converted into a low frequency of about 743 KHz, and both are frequency-multiplexed and recorded. The recording format on the tape is as shown in FIG. The minimum required VTR signals such as video signals (luminance signals, color signals), audio signals, and tracking signals are all frequency-multiplexed recorded by the rotary video head. Figure 12 shows the frequency band.
Shown in.

In FIG. 9, the magnetic tracks 401 and 402 of the video signal track unit 410 are video signal tracks, and each corresponds to one field. The hatched magnetic tracks 403 and 404 of the audio signal track section 411 are audio signal magnetic tracks. At both ends of the tape are fixed head cue tracks 405 and audio tracks 406. With 8mm video, the control track at the end of the tape is not used, so this track can be used as a cue track for cueing and addressing recorded contents. The width of one track (track pitch) is 20.5 μm, β method, VHS
A little wider than the pitch of the long-time mode of the method (β-III is 1
9.5 μm, VHS 6 hours mode is 19.2 μm). No guard band is provided between tracks to prevent crosstalk. Instead, azimuth recording with two heads is adopted to suppress crosstalk.

Next, a specific circuit operation of the conventional example will be described with reference to FIGS. 13 and 14 are block circuit diagrams of a conventional example, in which a video signal applied to a video signal input terminal 201 is applied to a video signal processing circuit 203 and a sync signal separation circuit 204. The output signal of the video signal processing circuit 203 is added to the adders 213 and 214 via the gate circuits 205 and 206.

On the other hand, the vertical synchronizing signal output from the synchronizing signal separation circuit 204 is supplied to the delay circuits 207 and 208.
The Q output of the delay circuit 207, which constitutes the head switch pulse generating means together with the synchronizing signal separation circuit 204, is supplied as a gate pulse to the first gate circuit 205 and a fourth gate circuit 212, which will be described later, and the Q bar output is the second output. Gate circuit 206
And is supplied as a gate pulse to a third gate circuit 211 described later. The output signal of the delay circuit 208 is the time axis compression circuit.
209 and erase current generator 240.

The audio signal applied to the audio signal input terminal 202 is passed through the time axis compression circuit 209, the modulation circuit 210 and the changeover switch 241 for switching between recording and erasing, and then the third gate circuit 211 and the fourth gate circuit. Supplied to the 212. The output of the erase current generator 240 is supplied to the third gate line 211 and the fourth gate line 212 via the changeover switch 241. 3rd gate line 211 and 4th gate line
The output signal of 212 is supplied to adders 213 and 214. The output signal of the adder 213 is given to the rotary transformer 217 via a changeover switch 215 for switching between recording and reproduction. The output signal of the rotary transformer 217 is the rotary shaft 219 and the rotary head bar 22.
The magnetic tape 22 is fed to the rotary magnetic head 221 through 0.
Recording current or erasing current flows to 3.

On the other hand, the output signal of the adder 214 is also interlocked with the selector switch 215, and the selector switch 21 for recording / playback switching is connected.
It is given to the rotary transformer 218 via 6. An output signal of the rotary transformer 218 is given to another rotary magnetic head 222 via a rotary shaft 219 and a rotary head bar 220, and a recording current or an erasing current flows through the magnetic tape 223. The magnetic tape 223 is guided by guide posts 224 and 225 located on both sides of a table guide drum 226 containing the rotary magnetic heads 221 and 222, and by a known magnetic tape running device (not shown) including a capstan and a pinch roller. Driving at a constant speed in the direction of arrow 227. Since a known table guide drum 226 can be used, a detailed description of the structure is omitted here.

During reproduction, the signal reproduced by the rotary magnetic head 221 passes through the rotary head bar 220, the rotary shaft 219, the rotary transformer 217, and the changeover switch 215, and then the separation circuit 228.
Is supplied to. On the other hand, the signal reproduced by the rotary magnetic head 222 is supplied to the separation circuit 229 via the rotary head bar 220, the rotary shaft 219, the rotary transformer 218 and the changeover switch 216. One output of separation circuit 228 and separation circuit 229
And the output of one of the two are supplied to the adder 230. Further, the other output of the separation circuit 228 and the other output of the separation circuit 229 are supplied to the adder 231. The output signal of the adder 230 is supplied to the video signal output terminal 233 via the video signal processing circuit 232. On the other hand, the output signal of the adder 231 is the time base correction circuit 23.
4, and is supplied to the audio signal output terminal 237 via the demodulation circuit 235 and the time axis expansion circuit 236.

Next, the operation will be described. The video signal applied to the video input terminal 201 is the video signal processing circuit 203.
Is converted into an FM signal. When the carrier color signal is included, the carrier color signal is converted to a low frequency band of about 1.2 MHz or less. Further, as a means for removing the adjacent color signal, for example, the phase of the carrier color signal may be rotated by 90 ° or inverted for every 1H (horizontal scanning period), without any problem. This is a technique for removing crosstalk between tracks using the line correlation of a carrier color signal. The video signal processed as described above is the first gate circuit 20.
5 and the second gate circuit 206.

On the other hand, when the video signal is also applied to the synchronizing signal separation circuit 204, a vertical synchronizing signal is obtained at its output end. This vertical synchronizing signal is supplied to the delay circuits 207 and 208. The delay circuit 207 has a frequency dividing function and a delay function, and the Q output terminal and the Q bar output terminal thereof are shown in FIG. 15 (b).
And pulse signal Q for head switching as shown in (c)
And Q bar to the first gate circuit 205 and the second gate circuit 206, respectively. These pulse signals Q, Q
Figure to clarify the phase relationship between the bar and the input video signal
The waveform of the input video signal is shown in 15 (a).

First gate circuit 205 and second gate circuit
At the output of 206, as shown in Figures 16 (a) and (b),
The processed video signal is output while the pulse signals Q and Q bar are at the H level. Those signals are added to the adders 213 and 21.
At 4, a modulated compressed audio signal or an erasing signal, which will be described later, is added and supplied to the changeover switches 215 and 216.

The compressed audio signal is modulated by a tape head system [especially pulse code modulation (PCM) or F
M, PM, AM, etc., or in some cases unmodulated A
C bias recording] is received by the modulation circuit 210. Especially PCM
Is advantageous in that a high S / N ratio can be expected, and well-known code error correction means can be used for dropout and the like. Such a modulated compressed audio signal is given to the third gate circuit 211 and the fourth gate circuit 212 to which the pulse signals Q and Q are supplied via the changeover switch 241. These gate circuits 211,21
2 outputs the compressed audio signal to the adders 213 and 214 while the pulse signals Q and Q are at the H level.

Further, the erase current generating circuit 240 has a certain frequency (for example, 10) whose transmission start time is controlled by the trigger signal T obtained by delaying the vertical synchronizing signal by the delay circuit 208.
A pulse signal is generated in the same manner as the recording of the compressed audio signal to the third gate circuit 211 and the fourth gate circuit 212, which generate an erasing current of 0 KHz) and are supplied with the pulse signals Q bar and Q via the changeover switch 241. The erase current is output to the adders 213 and 214 while Q bar and Q are at the H level. Figure 17 (a)
3B and 3B show waveform diagrams of the output signals of the adders 213 and 214, that is, the time-axis multiplexed signals of the processed video signal A and the processed audio signal B or the erased signal. By supplying these signals to the rotary magnetic heads 221 and 222 via the paths described above, a tape magnetic pattern as shown in FIG. 9 is obtained.

During reproduction, the movable contact pieces of the changeover switches 215 and 216 are changed over to the fixed contact P side. By doing so, the two-channel reproduction signals reproduced by the rotary magnetic heads 221 and 222 are transmitted via the rotary head bar 220, the rotary shaft 219, the rotary transformer 217 or 218, and the changeover switch 215 or 216, respectively, and the separation circuits 228 and 229. In, the input signal is separated into a video signal and an audio signal on the time axis. The separated video signal is converted by an adder 230 into a temporally continuous 1-channel video signal, which is then processed by a video signal processing circuit.
Supplied to 232. In the video signal processing circuit 232, the input signal is restored to the original video signal and the video signal output terminal
It is output to 233.

On the other hand, the separated audio signal is also converted into a channel signal by the adder 231 and supplied to the time axis correction circuit 234. The time axis correction circuit 234 is composed of a semiconductor memory such as a CCD (charge coupled device) or a BBD (bucket brigade device),
Here, the time base fluctuation of the tape head system (so-called jitter and skew distortion) is removed. The output signal of the time axis correction circuit 234 is demodulated to the original compressed audio signal by the demodulation circuit 235, and further converted to the original audio signal by the time axis expansion circuit 236 composed of a semiconductor memory such as CCD or BBD to output the audio. Output to terminal 237.

As described above, in the 8 mm video, the video signal and the audio signal of one field are recorded and reproduced as one track on the tape.

FIG. 18 is a block diagram showing the structure of another conventional video information recording / reproducing apparatus, which is a digital recording D1 system or D2 system VT used for business or broadcasting.
It is a figure which shows R. 101 is an A / D converter for converting an analog video signal into a digital video signal, 102 is an error correction encoder for adding an error correction code, 103 is a modulator for converting a digital signal into a signal suitable for recording on a magnetic tape,
104 is a rotary head drum, 105 is a magnetic tape, 106 is a recording / reproducing magnetic head, 107 is a demodulator for demodulating a reproduced signal, 108 is an error correction decoder for detecting and correcting transmission errors, and 109 is a digital video signal. It is a D / A converter for converting into an analog video signal.

FIG. 19 shows both types of tape formats. In both methods, a video signal and a 4-channel audio signal are recorded in different locations on the same track. However, in the D1 system, the audio signal is recorded at the center of the track, and in the D2 system, the audio signal is recorded at the end of the track. When the video signal and the audio signal are recorded on the same track, the magnetic head and the amplifier circuit required for recording and reproduction can be shared by the video signal and the audio signal. Further, as will be described later, a parity code required for error correction, a circuit for generating the parity code, and the like can be shared.

FIG. 20 shows the overall specifications of the D1 and D2 systems, FIG. 21 shows the specifications of the tape format, and FIG. 22 shows the specifications of the running system. From this, the area recording density, including the guard band, D1 method 21.5μm ² / bit, D2 scheme becomes 16.6μm ² / bit. A guard band is provided between recording tracks in the D1 system, but not in the D2 system. As a result, the track density of the D2 system is higher than that of the D1 system by about 15%, which also leads to the long-time recording of the D2 system.

On the other hand, without the guard band, it is easy to reproduce not only the original track signal but also the adjacent track signal. In order to cope with the crosstalk between tracks at the time of reproduction, the azimuth recording method is adopted in the D2 method. Normally, the head gap of the recording magnetic head and the head gap of the reproducing magnetic head are attached at the same angle with respect to the magnetic track. If an angle is given between both head gaps, the reproduction signal level shows an attenuation characteristic.

The azimuth angle θ in the D2 system
Is about ± 15 degrees as shown in FIG. As a result, even if a signal from an adjacent track is mixed during reproduction, the unnecessary component is attenuated. As a result, the influence of crosstalk is small even without a guard band. However, since the loss due to the azimuth angle cannot be expected with DC, it is necessary that the signal to be recorded has no DC component. For this reason,
The D2 method adopts a modulation method that has no direct current component.

In digital recording, it is not necessary to record the video signal all the time. The blanking period has a constant waveform irrespective of the contents of the image and can be combined after reproduction, so that only the effective image period is recorded in both the D1 and D2 systems. Further, the color burst signal included in the blanking period of the NTSC signal can also be synthesized after reproduction. This is because the sampling phase of the D2 system is defined as the I and Q axes, and the phase of the color burst (which is delayed by 180 + 33 degrees from the Q axis) can be determined by using the reproduced sampling clock.

FIG. 23 shows a pixel range actually recorded in the D1 and D2 systems. These effective pixels are divided into several segments. Pixels for 50 scanning lines in the D1 system and pixels for 85 scanning lines in the D2 system form a segment. That is, the pixels for one field consist of 5 segments in the D1 system and 3 segments in the D2 system.

The video signal in the segment is divided into 4 channels in the D1 system and is recorded in 2 channels in the D2 system. As a result, 1 of 1 segment
The number of pixels per channel is {(720 +
360 × 2) / 4} × 50 = 360 × 50 = 18000, and in the D2 system, {768/2} × 85 = 384 × 85 = 32640. At the time of distribution, it is considered that each channel is evenly distributed within the screen. As a result, even if the characteristics of any particular channel are deteriorated, the code errors caused thereby are not concentrated in one place on the screen and are not conspicuous. Therefore, the effect of correction is great even for errors that cannot be corrected.

Both the D1 and D2 systems use two types of error correction codes called outer code and inner code. Inner Code,
In the process of generating the outer code, the order of the codes is actually changed. This is called shuffling. The shuffling disperses the influence of code errors, improves the correction capability, and reduces screen deterioration due to uncorrected errors. This includes shuffling for one scanning line before generating the outer code and shuffling within one sector before adding the outer code and before generating the inner code. As described above, in the D1, D2 system VTR, the video signal and the audio signal of one field are recorded over a plurality of tracks on the tape.

In a home VTR, the current NTSC or PA
In order to record the information of the L standard television signal completely, the carrier frequency of the FM luminance signal is increased, the band and deviation are expanded, and the resolution and C / N have been improved. In terms of N ratio, waveform reproducibility, etc., it has not yet caught up with the commercial VTR.

However, expectations for downsizing of the equipment are high,
Further improvements in performance as well as reductions in weight and size are required, and it is difficult to improve current technology alone. On the other hand, in the field of commercial / broadcasting VTRs, rapid digitalization has progressed, and multifunctional and high performance devices have been realized. In the field of broadcasting, most of them have been replaced by digital VTRs.
However, the tape consumption of digital VTR is very large,
It hinders longer operation and miniaturization.

In recent years, paying attention to the redundancy of information that video has,
Research on compressing recorded information has become popular, and utilization of this for VTR is also under study. Due to the high image quality of digital, high-density recording, and tape consumption reduction due to information compression, it is expected to realize a compact, lightweight, high image quality, and long-time VTR.

FIG. 24 shows a high-efficiency coded video information compression system (according to CCITT H.261 or the like) used in the field of communication such as a videophone and a video conference. Reference numeral 101 is an A / D converter for converting an analog video signal into a digital video signal, 110 is a high efficiency encoder for compressing and coding the video signal, and 112 is a buffer used for sending the generated compressed code at a constant speed. Memory, 102 is an error correction encoder that adds an error correction code, 103 is a modulator that converts a digital signal into a transmission signal for communication, 114 is a communication path, 107 is a demodulator that demodulates a received signal digitally, and 108 is a transmission An error correction decoder for detecting and correcting errors, 113 is a buffer memory used for supplying the compressed code received at a constant speed in accordance with the request of the next stage, 111
Is a high-efficiency decoder that expands the compressed video signal into the original signal, and 109 is a D / A converter that converts the digital video signal into an analog video signal.

The redundancy of the input video signal always changes, and therefore the code amount compressed and encoded by using this redundancy also changes. However, the amount of information transmitted on the communication path 114 is limited, and in order to maximize the performance, the buffer memory 113 is used to absorb fluctuations in the code amount and to prevent memory overflow and underflow. Controls the amount of information. FIG. 25 shows the buffer operation on the receiving side. The data received at a constant rate is stored in the buffer memory, and when the data amount reaches BO, decoding of the code is started. The data of d1 is consumed for displaying the first screen, and the amount of accumulated data becomes B1 when the decoding of the second screen is started. Data accumulation and consumption are repeated in the same manner. Although the data consumption differs depending on the display screen, the average data consumption and the reception rate are equal. Although the receiving side has been described here, the transmitting side performs an operation that is completely opposite to that of the receiving side.

Since the communication device is controlled as described above, the relationship between the field of the input video and the code to be communicated is not clear. However, unlike applications in the communication field, VTRs are required to have special playbacks such as still playback, slow playback, high-speed playback, etc. that are different from normal playback, assembling editing, insert editing, etc. It is preferable that the relationship with In order to make a practical VTR, it is essential to select a recording format that can solve these problems.

To compress a moving image such as a television signal,
An intra-field (or intra-frame) whose encoding is completed in a single field (or frame) regardless of other fields (or frames) and a predictive field (predictive-encoding using information of other fields or frames) There is a compression method using (or prediction frame), and generally, the amount of information of an intra field (or intra frame) that does not use inter-field (or inter-frame) prediction is a prediction field (or It is more than twice the code amount of (predicted frame).

Therefore, if recording areas (track numbers) of the same size are assigned to the intra field (or intra frame) and the prediction field (or prediction frame), a sufficient recording area can be obtained in the intra field (or intra frame). The fourth problem is that the recording area is wasted in the prediction field (or the prediction frame).

One object of the present invention is to create an intrafield (or intraframe) for which motion compensation is not performed every n fields (or n frames), and other fields (or frames) are intrafields (or intraframes). It is an object of the present invention to solve the first problem described above and to provide a high-efficiency coding device having a small hardware scale by performing motion-compensated prediction with.

Another object of the present invention is to set a reference image using a method fixed to a certain degree for an image having no normal scene change, and a scene change occurs in the process of motion compensation prediction. Sometimes, by switching the reference image so as to suppress the increase in the generated information amount as much as possible, the second problem is solved, the generated information amount can be suppressed, and the S of the image can be suppressed while suppressing the increase in the hardware.
An object of the present invention is to provide a high efficiency coding device capable of maintaining the / N ratio.

Still another object of the present invention is to perform motion compensation prediction by setting a reference image using a method fixed to a certain degree for a normal video without scene change, and performing a motion compensation prediction within the process. When a scene change occurs in, the video immediately after the scene change is encoded in the field (or in the frame) as an intra field (or intra frame) to eliminate the third problem described above, and It is an object of the present invention to provide a high-efficiency coding device capable of suppressing deterioration of image quality as much as possible.

Still another object of the present invention is to solve the fourth problem described above by collectively recording signals of a plurality of fields (or frames) as one recording unit on a predetermined number of tracks. Special playback required for VTR,
An object of the present invention is to provide a video information recording / reproducing device that can handle editing.

[0061]

In the high-efficiency coding apparatus of the present invention, the image quality deterioration is conspicuous on a small hardware scale by using only the intra field (or intra frame) as the reference image for motion compensation prediction. Do not compress information.

In another high-efficiency coding apparatus of the present invention, usually, motion-compensated prediction is performed using a fixed reference image,
When a scene change occurs in the process of the motion compensation prediction, the reference image is adaptively switched and an increase in the amount of information is suppressed. At this time, in order to determine a scene change, for example, the number of blocks determined to be in the intra mode is counted, and when the number of blocks in the intra mode that is equal to or greater than the threshold value set is generated, the next field (or frame) Switch the reference image of. Therefore, the coding mode of the block is monitored, the scene change is judged, the code amount generated by switching the reference image of the motion compensation prediction is suppressed, and the S / N of the reproduced video is kept high.

If a scene change is detected, the image immediately after the scene change is used as an intra image, and the amount of information is compressed, the coding error is only the error of this field (or frame), and the motion of the next field (or frame). The influence on the compensation process is reduced. That is, when motion compensation prediction is performed across a scene change, the amount of information generated in the field (or frame) at that time increases, and even if the amount of information is compressed, the effect of coding error increases, so If the amount of information is equivalent, the subjective evaluation is higher when encoded as an intra field (or intra frame).

In still another high efficiency coding apparatus of the present invention,
When a scene change occurs in the motion compensation prediction processing unit, the field (or frame) immediately after the scene change that has occurred is encoded as an intra field (or intra frame). Then, even if the information amount of the field (or frame) is compressed into the prediction field (or the prediction frame), the image quality deterioration of the video can be suppressed more by encoding as the intra field (or the intra frame).

In the video information recording / reproducing apparatus of the present invention, the input n-field (or n-frame) signals are combined into one recording unit block, and the amount of information to be recorded and 1
Recording is performed on a predetermined number of tracks calculated from the recording capacity of the tracks. The blocks grouped into recording units are compression-encoded so as to include at least one intra field (or intra frame). Input n
The field (or n frame) television signal is compression-encoded as one recording unit block by the high-efficiency encoder. A compression-encoded television signal of n fields (or n frames) is divided into m track recording areas and recorded. The reproduced m track signal is restored to an n field (or n frame) television signal by the high efficiency decoder.

[0066]

EXAMPLES Example 1. A first embodiment of the present invention will be described below with reference to the drawings. FIG. 26 is a block diagram of the first embodiment of the present invention. In FIG. 26, 1 is a digital video input terminal, 2 is a digital video input terminal 1
Blocking circuit 30 for blocking the input digital video signal from the input circuit 30 performs motion compensation prediction between the block output from the blocking circuit 2 and the intra field, and outputs an error signal between the input block and the prediction block. A motion compensation prediction circuit, 31 is a determiner that selects the smaller sum of absolute values of the input signal output from the blocking circuit 2 and the prediction error signal from the motion compensation prediction circuit 30, and 32 is based on the determined mode A first switch that selectively outputs the coding block output from the blocking circuit 2 and the determiner 31, 33 is an orthogonal transform circuit that performs orthogonal transform on the coding block output from the first switch 32, and 34 is A quantization circuit for quantizing the output of the orthogonal transformation circuit 33, and 11 a transmission line.

Reference numeral 35 is a second for selecting and outputting the quantization result output from the quantization circuit 34 only in the case of the intrafield.
A switch, 36 is an inverse quantization circuit that inversely quantizes the output of the second switch 35, 37 is an inverse orthogonal transformation circuit that inversely orthogonally transforms the output of the inverse quantization circuit 36, and 38 is output from the inverse orthogonal transformation circuit 37. This is an image memory for storing the reproduced image of the intra field for one field and outputting the reference image of the search range for the prediction field to the motion compensation prediction circuit 30.

As a prediction method performed by such a circuit block, for example, the one shown in FIG. 27 can be considered. In this method, an intra field is inserted every four fields and three fields in between are used as prediction fields. In FIG. 27, the first field F1 is an intra field, and the second, third, fourth fields F2, F3, F4 are prediction fields. In this method, the first, second, third, and fourth fields F2, F3, and F4 are predicted from the first field F1. First, the first field F1 which is an intra field is blocked within the field, subjected to orthogonal transformation, quantized, and then coded.

In the local decoding loop, the quantized signal of the first field F1 is decoded / reconstructed. This reconstructed image is the next second field F2, third field F
3, Used for motion-compensated prediction of the fourth field F4. Next, the second field F2 is motion-compensated and predicted using the first field F1, and the obtained error block is orthogonally transformed,
Encoding is performed in the same manner as the first field F1. At this time, if the sum of absolute values of the input block is smaller than the sum of absolute values of the error block, the input block, not the error block, is orthogonally transformed and encoded in the same manner as the first field F1.

On the other hand, the third field F3, the fourth field
Similarly to the second field F2, F4 is also motion-compensated and predicted using the first field F1 and encoded. Third field F3,
Also in the fourth field F4, if the AC power of the input block has a smaller sum of absolute values than the power of the error block, the input block, not the error block, is orthogonally transformed and encoded in the same manner as in the first field F1.

Next, the operation will be described. The video signal input from the digital video input terminal 1 is divided into blocks, for example, 8 pixels.times.8 lines as a unit, by the blocking circuit 2 regardless of the intra field and the prediction field. Further, the motion compensation prediction circuit 30 performs motion compensation prediction on the input block output from the blocking circuit 2 in the case of a prediction field, using the reproduced image data of the intra field stored in the image memory 38 as a reference image.

In the motion compensation prediction circuit 30, a search range block for motion detection is performed with a size of 16 pixels × 16 lines, for example.
Find the motion vector. Further, an error signal between the reference image and the input image is obtained according to the motion vector obtained by the motion detection, and the error signal is output to the determiner 31 together with the motion vector.
The determiner 31 obtains the sum of absolute values of the components of each block of the input block output from the blocking circuit 2 and the error block output from the motion compensation prediction circuit 30. The input block is I (i, j) (i, j = 1 to 8),
The sum of the absolute values is Is, and the error block is P (i, j).
(I, j = 1 to 8), where Ps is the sum of the absolute values thereof, I
s and Ps are represented by the following equations.

[0073]

[Equation 1]

Here, when Ps <Is, it is judged that the error block has less information amount than the input signal block,
The error block is output to the first switch 32 together with the motion vector. On the other hand, when Ps ≧ Is, it is determined that the input signal block has a smaller amount of information than the error signal block, and the input block and the forced intra signal indicating that the block is the forced intra block are replaced with the motion vector instead of the motion vector. 1 Output to switch 32.

The first switch 32 selects the output of the blocking circuit 2 in the intra mode, and selects the output of the determiner 31 in the prediction mode and outputs it to the orthogonal transform circuit 33. In the orthogonal transformation circuit 33, for example, two-dimensional DCT is applied to each input 8 × 8 block. Quantization circuit 34
Then, the orthogonal transform coefficient output from the orthogonal transform circuit 33 is variable-length coded and quantized. In the prediction mode, the quantization circuit 34 quantizes the motion vector or the forced intra signal in addition to the orthogonal transform coefficient, and outputs it to the transmission path 11 in addition to the orthogonal transform coefficient.

On the other hand, the second switch 35 outputs the orthogonal transform coefficient quantized by the quantizing circuit 34 to the inverse quantizing circuit 36 only in the case of the intrafield in order to use it as reference data for motion compensation prediction. In the inverse quantization circuit 36, the quantization circuit
The variable length coded data is inversely quantized by 34 and variable length decoding is performed, and the result is output to the inverse orthogonal transform circuit 37. The inverse orthogonal transform circuit 37 performs, for example, two-dimensional inverse DCT to restore the intrafield block. Inverse orthogonal transformation circuit
Each block of the intra field restored by 37 is stored in the image memory 38. The image memory 38 stores one field of the restored image of the intra field as reference data in the case of motion compensation prediction, and further outputs a reference image in the motion vector detection range to the motion compensation prediction circuit 30.

In the above embodiment, the block size of the orthogonal transformation is set to 8 pixels × 8 lines, but it is not necessarily 8 pixels × 8 lines, and the block size of n pixels × m lines is used. Good. Similarly, the motion vector detection range does not have to be 16 pixels × 16 lines, and may be k pixels × s lines (k ≧ n, s ≧ m). Although the predictive coding is completed every four fields, the predictive coding is not necessarily limited to four fields, and the predictive coding may be completed every arbitrary field.

Although the predictive coding is completed for each arbitrary field, the predictive coding is not necessarily required for each field and may be completed for each arbitrary frame. In the above embodiment, the decision unit 31 outputs the smaller absolute value sum of the output of the blocking circuit 2 and the output of the motion compensation prediction circuit 30 to the first switch 32. However, the motion compensation decision is not performed. Alternatively, only the output of the motion compensation prediction circuit 30 may be output to the first switch 32.

Example 2. In the first embodiment, the decision unit 31 outputs the smaller absolute value sum of the output of the blocking circuit 2 and the output of the motion compensation prediction circuit 30 to the first switch circuit 32. In a field where the result is more in the forced intra mode than in the prediction mode, it may be determined that a scene change has occurred, and the entire field may be encoded as the intra mode. An example configured in this way is the second embodiment.

FIG. 28 is a block diagram showing the structure of the second embodiment. In the figure, 40 selects the smaller absolute value sum of the input block output from the blocking circuit 2 and the prediction error block from the motion compensation prediction circuit 30, and further selects the input block from the blocking circuit 2. A field that has more fields is an intrafield determiner, 41 is a first field memory that stores the input block output from the blocking circuit 2 as intrafield data, and 42 is an output from the determiner 40. A second field memory for storing a block of a prediction field, and an orthogonal transform circuit 43 selects the output of the first field memory 41 when the intra mode / determination unit 40 determines that there are more forced intra modes than prediction modes. It is a first switch for outputting to 33 and for selecting the output of the second field memory 42 otherwise.

Next, the operation will be described. Since the operation from the digital video input terminal 1 to the motion compensation prediction circuit 30 is the same as that of the first embodiment, it will be omitted. The determiner 40 is the first embodiment.
Similarly, the smaller one of the sums of the absolute values of the respective components of the input block output from the blocking circuit 2 and the error block output from the motion compensation prediction circuit 30 is selected and output. Here, when the output of the motion compensation prediction circuit 30 is selected, the determiner 40 outputs the block of the error signal together with the motion vector.

When the output of the blocking circuit 2 is selected, it is output together with a signal indicating that it is a forced intra block. If the number of forced intra blocks is n or more within a field, the determiner 40 determines that a scene change has occurred, and outputs a control signal for encoding all the current fields in the intra mode.

The output of the discriminator 40 is stored in the second field memory 42 as data in the prediction mode, and the data for one field is stored and then output to the first switch 43. On the other hand, the output of the blocking circuit 2 is stored in the first field memory 41 as intra mode data, and the data for one field is stored and then output to the first switch 43. The first switch 43 selects the output of the first field memory 41 when the intra mode and the decision unit 40 determines that the intra mode is forcibly set, and otherwise selects the output of the second field memory 42. And outputs it to the orthogonal transform circuit 33. The operations from the orthogonal transform circuit 33 to the image memory 38 are the same as those in the first embodiment, and will be omitted. However, if the determiner 40 determines that a scene change has occurred, the contents of the image memory 38 also need to be updated, so that the second switch 35 reverses the output of the quantization circuit 34 as in the intra mode. Output to the quantization circuit 36.

Here, for a certain sample image, as shown in FIG.
An example in which encoding and decoding are performed using the three types of predictive encoding shown in FIGS. 4 and 29 will be described. The predictive coding method shown in FIG. 29 is a method in which inter-field prediction is performed in each frame and the third field F3 is predicted from the first field F1. Here, the encoding method according to FIG.
FIG. 30 shows the results of simulations performed on 5 seconds of sample images in which a scene change exists, using FIG. 4 as method 2 and FIG. 29 as method 3.

Similarly, image 5 with no scene change
Figure 31 shows the result of simulation performed for seconds. The sample image is a 4: 2: 2 component signal (Y: 720 × 240, Cb, Cr: 360 × 240, 60Fiel.
d / sec) is used. From the results of FIGS. 30 and 31, method 3 is effective in the case of an image including a scene change, from the viewpoint of S / N ratio.

However, in the case of a video that does not include a scene change, it can be seen that there is not much difference between methods 1 to 3. As a result, when a scene change occurs, the intra-field is forcibly forced to realize a high-efficiency coding apparatus having a smaller hardware size than the conventional predictive coding apparatus.

In the second embodiment, an intra mode is created for every n fields, and the subsequent n-1 fields are predictively encoded from the intra field. When a scene change occurs, the intra field is forcibly created and the remaining Although the field is predicted from the forced intra-field, it is not always necessary to have an intra-field for every n fields, and when the forced intra-field occurs, the following n-1 is taken from the forced intra-field as a starting point.
The fields may be predictively coded. Further, although predictive coding is performed in field units in the above-described embodiment, predictive coding is not necessarily performed in field units, and predictive coding may be performed in frame units.

As described above in detail, in the high-efficiency encoders of the first and second embodiments, an intra field is created for every n fields, and for other fields, motion compensation prediction is performed using this intra field as a reference image. Therefore, the hardware size of the arithmetic circuit or the like for obtaining the motion vector can be reduced.

Example 3. FIG. 32 is a block diagram showing the configuration of the high efficiency coding apparatus according to the third embodiment. In FIG. 32, 1
14 to 16 to 20 are the same as the conventional device in FIG. 50 is a mode counter that counts the number of intra mode blocks, 51 is a direction switching circuit that compares a predetermined number of blocks and the number of intra mode blocks from the mode counter, and determines a reference image for the next field, 52 Is an image memory which stores output blocks for performing motion compensation prediction and outputs a reference image of the next field as a search range.

Next, the operation will be described. The input digital video input signal is m [pixels] by the blocking circuit 2 regardless of the intra field and the prediction field.
The input block is divided into xn [lines] as one unit and cut out. In the input block, the difference in pixel units from the prediction block is calculated in the subtractor 3 to obtain the error block. In this way, the input block and the error block are input to the first switch circuit 7, respectively.
Further, the error block is input to the error power calculation circuit 4 to calculate its power, and the error power is calculated.

The input block is also input to the original image power calculating circuit 5 to calculate the AC power, and the original image power is calculated. The outputs of the error power calculation circuit 4 and the original image power calculation circuit 5 are input to the determination circuit 6, whichever of the two powers is selected, and is input to the first switch circuit 7 as a mode signal. At this time, if the error power is smaller than the original image AC power, the prediction mode signal is output so that the first switch circuit 7 outputs the error block as the coding block in the prediction mode. If the original image power is smaller than the error power, the first switch circuit 7 is selected as the intra mode.
In, the intra mode signal is output so that the input block is output as the coding block.

The mode signal from the discrimination circuit 6 is input to the mode counter 50. Since the input mode signal is generated for each block of the prediction field, the mode counter 50 counts the number of blocks for which the intra mode or the prediction mode is selected among the number of blocks for one field. Then, the number of blocks in which the intra mode or the prediction mode is selected is output to the direction switching circuit 51. The direction switching circuit 51 compares the number of predetermined blocks (less than the number of blocks for one field) with the number of blocks selected from the mode counter 50 for which the intra mode is selected, and outputs a reference image switching signal to the image memory 52. To do.

If the number of predetermined blocks in the direction switching circuit 51 is larger (smaller) than the number of blocks for which the intra mode (or the prediction mode) is selected, the reference image switching signal is set so that the reference image is not switched.
It is output to 52. Further, the number of predetermined blocks in the direction switching circuit 51 is the intra mode (or the prediction mode).
If the number of blocks selected is smaller (larger), the reference image switching signal is output to the image memory 52 to switch the reference image.

The first switch circuit 7 outputs the input block or the error block as a coding block based on the mode signal determined by the discrimination circuit 6. At this time, when the input block is the intra-field, the first switch circuit 7 always outputs the input block as the coding block. The coding block is input to the DCT circuit 8 and converted into DCT coefficients. The DCT coefficient is quantized into a predetermined number of bits according to the weighting process and the threshold process by the quantizing circuit 9. Each DCT coefficient quantized to a predetermined number of bits is converted into a code suitable for the transmission line 11 by the first encoding circuit 10, and the transmission line 11 is converted.
It is output to 11.

The DCT coefficient weighted by the quantizing circuit 9 and processed by the thresholding process enters the local decoding loop 20 and is inversely weighted and inversely quantized by the inverse quantizing circuit 12. Inverse weighting and inverse quantized DCT in local decoding loop 20
The coefficients are transformed into decoding blocks by the inverse DCT circuit 13. The decoded block is then added pixel-by-pixel with the prediction block by adder 14. This prediction block is used by the subtractor 3.

The result of addition by the adder 14 is written as an output block in a predetermined position of the image memory 52. The image memory 52 switches the reference image according to the reference image switching signal from the direction switching circuit 51 and outputs the motion detection search range to the MC circuit 16. The size of the search range block for this motion detection is, for example, i [pixel] × j [line] (i ≧ m,
j ≧ n). The MC circuit 16 includes a motion detection search range block output from the image memory 52 and a blocking circuit 2.
And the input blocks output from are input respectively.
The MC circuit 16 detects a motion from each input block and extracts a motion vector of the input block.

Then, the motion vector extracted by the motion detection in the MC circuit 16 is input to the MIX circuit 17. MIX
The circuit 17 synthesizes the motion vector input from the MC circuit 16 and the mode signal determined by the discrimination circuit 6. In this way, the motion vector and the mode signal synthesized by the MIX circuit 17 are converted into a code suitable for the transmission line 11 by the second encoding circuit 18, and the transmission line 11 together with the corresponding encoded block is converted.
Is output to.

Further, the prediction block output from the MC circuit 16 is output as a block in the MC circuit 16 in the size m [pixel] × n [line] equal to the input block from the motion detection search range. This prediction block is input to the second switch circuit 19, and is output from each output according to the field of the input block currently processed and the mode signal of the decoding block. A prediction block is output from one output of the second switch circuit 19 to the subtractor 3 according to the processing field. A prediction block is output from the other output according to the mode signal of the decoding block at that time and the processing field.

In the present invention, if a scene change occurs in frame units when the prediction method as shown in FIG. 4 is used in the case of normal video, the number of blocks for selecting the intra mode when encoding the video immediately after the scene change increases. However, the subsequent reference image can be switched as shown in FIG.

The operation of the third embodiment will be summarized using the flowcharts of FIGS. 33, 34 and 35. FIG. 33 is a flowchart showing the overall operation of the third embodiment, FIG.
35 is a flowchart showing the contents of the intra-field processing of step S103 and the prediction field processing of S104 in FIG.

First, the field number fn indicating the field in the motion compensation processing unit is set to 0 (step S10).
1). This field number fn will be described with reference to FIG. 4. The first intra-field F1 in the motion compensation processing unit has a field number fn = 0, the prediction field F2 has a field number fn = 1, and the next prediction field F3 has a field number fn =. 2. The last prediction field F4 in the motion compensation processing unit is set to the field number fn = 3. Since the motion compensation processing is started right now, the first processing field is always the head in the motion compensation processing unit. Since it is a field and an intra field, the field number fn = 0 is set in step S101. The reference image switching flag Rfn, which is a flag for determining the presence or absence of a scene change, is set during the subsequent prediction field processing, but here it is set to Rfn = 0 for initialization.

Next, whether the field number fn = 0 or not,
That is, it is determined whether the first field in the motion compensation prediction processing unit is an intra field (step S10).
2). If fn = 0 at this time, this field is processed as an intra field (step S103). On the other hand, if fn ≠ 0, the field is processed as a predictive field. Each of these processes will be described in detail later. After each field is processed, the field number fn is incremented to point to the next field (step S105). Note that such field numbers can be controlled by signals from a microcomputer or the like in actual hardware.

Subsequently, it is determined whether or not the field number fn indicating the next field is a numerical value indicating the field in the motion compensation processing unit (step S10).
6) A number that does not indicate a field in the motion compensation processing unit. For example, in the example of FIG. 4, the motion compensation processing unit is completed with 4 fields, and the field number fn of the intra field is set to 0. If the number is fn = 4, it means that a series of motion compensation prediction units has ended, and if fn <4, it is determined that the next field is still within the motion compensation processing unit, and the processing is repeated. ..

When a series of motion compensation prediction processing units is completed, it is determined whether or not the processing of all desired fields is completed (step S107). This is determined by, for example, whether or not the end switch of this high-efficiency encoder is activated. Then, if the next field is to be processed, the variable is initialized and the process is repeated for encoding the next motion compensation prediction processing unit. If the operation of the high-efficiency encoder is finished, the encoding is finished.

Next, a diagram of intra-field processing is shown.
This will be described with reference to the flowchart of 34. A field determined to be processed as an intra field in step S102 of FIG. 33 is first divided into blocks of a predetermined size m [pixel] × n [line] in the processed field (step S201). Next, orthogonal transformation such as DCT is performed on the block size (step S202).
The orthogonally transformed data is quantized into a predetermined number of bits set in each sequence (step S203).

In the case of orthogonal transformation such as DCT, quantization is usually performed such that a large number of bits are assigned to low-order sequences among direct current and alternating current, and a small number of bits are assigned to high-order sequences among alternating current. Done. The quantized data is converted into a code suitable for transmission (step
S204), the encoded data is transmitted (step S2)
05). Further, it is determined whether or not the processing for one field is completed by counting the number of processing blocks (step S20).
6). If the processing in one field is not completed, the processing of the next block is performed again. If the processing of the blocks in one field is completed, the processing of the intra field is completed.

Next, the predictive field processing will be described with reference to the flowchart of FIG. The field determined to be processed as the predictive field in step S102 of FIG. 33 is whether the reference image switching flag Rfn-1 = 0 at the time of the field processing before the field, that is, the field before the field currently to be processed. It is determined whether or not a scene change is detected during field processing (step S301). If Rfn-1 = 0, motion compensation prediction is performed from the reference image at the same position as before (step S30
2) If Rfn-1 = 1, a scene change is detected when the field number fn-1 is processed, and the reference image is switched to the motion compensation prediction of the field number fn and it is different from the previous position. Motion-compensated prediction is performed using the image of the field at the different position as a reference image (step S30).
3).

Next, for example, a variable COUNT that counts the number of blocks in which the intra mode is selected in one field to be processed is set to 0 (step S304). The variable COUNT will be described in detail later. Then, the input image has a predetermined size m within the processing field.
Blocked into [pixels] × n [lines] (step
S305). Motion-compensated prediction processing is performed on blocks divided into m × n sizes (step S306). At this time, using the reference image set in one of steps S302 and S303, the difference in pixel unit between the predetermined area of the past image and the block that is now divided is input to the error power calculation circuit 4 as an error block, and the error is calculated. Electric power P1 is calculated (step S307). That is, the amount of information generated by motion compensation prediction is reduced by using the set reference image. Also,
The divided blocks are input to the original image power calculation circuit 5,
The original image AC power P2 is calculated (step S308).

The magnitudes of the calculated electric powers P1 and P2 are compared (step S309). If the error power P1 is smaller than the original image AC power P2, the error block (the difference value of the motion-compensated prediction block) is selected (step S310). On the other hand, if the error power P1 is larger than the original image AC power P2, the input block (original image that is still blocked) is selected (step S311), and the number of times the input block is selected as the encoding block, that is, the intra mode is processed. The number of blocks to be processed is counted in one field (step S312). The variable serving as the counter at this time is COUNT set to 0 in step S304. It is always set to 0 at the start of processing in field units, and the number of blocks in which the intra mode is selected is counted during processing of one field.

Each selected block is subjected to orthogonal transformation (step S313) and quantized into a predetermined number of bits set in each sequence (step S314). For example, in the case of orthogonal transform such as DCT, usually, quantization is performed so that a large number of bits are allocated to a low-order sequence among DC and AC, and a small number of bits is allocated to a high-order sequence of AC. .. The quantized data is converted into a code suitable for transmission (step S315), and the coded data is transmitted (step S316). It is determined whether or not the processing for one field is completed by counting the number of processing blocks (step S317). If the processing in one field is not completed, the processing of the next block is performed again.

If the processing of blocks in one field is completed, the number of input blocks processed as coding blocks in the processing of one field, that is, the number of blocks in which the intra mode is selected is set in advance. The threshold value TH is compared (step S318). This TH
Is a predetermined number less than or equal to the number of blocks in one field. For example, the total number of blocks in one field is 2700, and TH is set to be 2700 or less and TH = 1000. If the count COUNT of selecting the input block as the coding block is smaller than the set threshold TH, the field (field number fn) that has just been processed
There is no scene change between the reference image used for motion compensation prediction of that field and the reference image used for motion compensation of the next field (field number fn + 1). The reference image switching flag Rfn = 0 is set to use (step S319).

If the count COUNT when the input block is selected as the coding block is larger than the set threshold TH, the field (field number fn) which has just been processed.
) And the reference image used for motion-compensated prediction of that field, there is a scene change, and the reference image for motion compensation of the next field (field number fn + 1) is in the normal position. Instead of an image, a field at a position different from the previous one, for example, a field that has not been in the position to be the reference image until now and has been processed is used as the reference image. Therefore, the reference image switching flag Rfn = 1 is set (step S320). In this way, the reference image switching flag Rfn is set, and the predictive field processing ends.

FIG. 36 shows the transition of the information amount for 5 seconds when predictive coding is performed according to the third embodiment.
The transition of N is shown. There is a scene change at point B,
The increase in the amount of information is suppressed more than in the case of point A in FIG. Moreover, there is no noticeable deterioration of the S / N ratio.

Examples 4, 5. In Example 3, as a method of selecting a coding block from an error block and an input block, the respective powers were calculated and compared, and the number of blocks selecting the intra mode was counted.

In the fourth embodiment, as a method of selecting a coding block from an error block and an input block, entropy in each block is calculated, and as in the third embodiment, the discrimination circuit 6 determines the entropy of the error block and the input block. Of the error block or the input block is selected as the coding block.

The fifth embodiment is a method of selecting a coding block from an error block and an input block by adding the absolute values of pixels in each block, and raising the sum of the absolute values of the input block and the error block to the power r. And the r of the sum of absolute values of error blocks is calculated by the discrimination circuit 6 as in the third embodiment.
The power is compared with the r-th power of the sum of absolute values of the input blocks to determine whether to select an error block or an input block as a coding block.

Example 6. In the third embodiment, the discrimination circuit 6 compares the powers of the input block and the error block, respectively, but in the sixth embodiment, the power of the input block or the error block is compared when the power of the input block and the error block are compared. After offsetting at least one of the electric powers, the two are compared. For example, a positive offset is applied to the power of the input block and the power of the error block is compared. In this way, when there is no great difference between the power of the input block and the power of the error block, it is possible to increase the number of blocks that select the differential power and prevent the excessive intra mode from occurring.

FIG. 38 is a flow chart showing the predictive field processing in the sixth embodiment. In FIG. 38, the parts with the same step numbers as in FIG. 35 indicate the same parts. First,
Steps S301 to S308 are the same as in the third embodiment. The error power P1 calculated from the error block is compared with the original image AC power P2 calculated from the input block (original image block) to which a predetermined offset of α has been added (step S330). By doing this, P1
<P2 + α is more difficult to satisfy than in the third embodiment, and the number of blocks for selecting the intra mode is reduced. Then, generation of excessive intra mode is suppressed, and the amount of generated information can be kept stable. The subsequent operations from step S310 to step S320 are the same as in the third embodiment.

Examples 7, 8. In the seventh embodiment, when comparing the entropy of the input block and the entropy of the error block as in the fourth embodiment, at least one of the entropy of the input block and the entropy of the error block is offset, and both are compared. is there. For example, a positive offset is applied to the entropy of the input block and the entropy of the error block is compared with the entropy of the error block. In this way, if there is no great difference between the entropy of the input block and the entropy of the error block, it is possible to increase the number of blocks that select the error block and prevent the occurrence of excessive intra mode.

In the eighth embodiment, when comparing the absolute value sum of the input block and the absolute value sum of the error block as in the fifth embodiment, the sum of the absolute value of the input block is the r-th power or the absolute value sum of the error block. An offset is given to at least one of the r-th powers and the both are compared. For example, a positive offset is given to the r-th power of the sum of absolute values of the input block and the result is compared with the r-th power of the sum of absolute values of the error block. In this way, if there is no difference equal to or more than the offset given to the r-th power of the sum of absolute values of the input block and the r-th power of the sum of absolute values of the error block, the number of blocks that select the error block increases and excessive intra mode occurs. It is possible to prevent

Example 9. In the third embodiment, the mode counter 50 counts all the blocks for which the intra mode is selected among the blocks for one field, but the ninth embodiment does not count the blocks for one field but one field. When the mode signal of a predetermined number of blocks in the period is determined, the total number of blocks or the ratio of the number of blocks for which the intra mode is selected to the number of blocks for which the mode signal is determined is output to the direction switching circuit 51 to switch the direction. The circuit 51 outputs the reference image switching signal from the ratio. By doing so, it is possible to determine the reference image of the next field without encoding all blocks for one field.

FIG. 39 is a flow chart showing the predictive field processing of the ninth embodiment. In FIG. 39, the parts given the same step numbers as in FIG. 35 indicate the same parts. First, steps S301 to S303 are the same as in the third embodiment.
After setting the reference image for the motion compensation prediction process of the next field (steps S302, S303), for example, the number of intra modes generated in the field when processing one field, that is, the input block as the coding block is set. A variable COUNT that counts the number of selected blocks
And a variable B that counts the number of blocks processed up to now in the processing within the one field are set to 0 (step S340).

Thereafter, steps S305 to S316 are the same as in the third embodiment. After encoding, set variable B to 1
The number of processing blocks up to the present is counted by incrementing by one (step S341). B varies from 0 to the maximum number of blocks in one field. Reference image switching determination processing for determining whether to switch the reference image for the motion compensation prediction processing of the next field is performed (step S342). The next step S317 is the same as in the third embodiment.

FIG. 40 is a flow chart showing the contents of the reference image switching determination process of step S342 of FIG. 39, and the process will be described with reference to FIG. Reference image switching flag Rfn
Is determined to be 0 (step S351), the flag Rfn
If is not 0, the process ends. If the flag Rfn is 0, the number of times the input block is selected as the coding block, COUNT, and the ratio of the variable B that counts the number of processing blocks up to the present in one field are compared with the threshold value TH (step S352). If the ratio is smaller than the threshold TH, the process is terminated, and if the ratio is larger than the threshold TH, the flag Rfn is set to 1 (step S3
53), the process ends.

Example 10. Next, a tenth embodiment will be described with reference to FIG. 41 showing the configuration. In FIG. 42, 1,
3 to 6, 8 to 16, 18, and 20 are the same as those of the conventional device shown in FIG. 60 is an image memory that stores the input video, 61 is an SC detection circuit that detects a scene change of the video and outputs a signal to that effect, 62 is an input block cut from the original image and a prediction block by motion compensation prediction A first switch circuit for switching between the generated error block and 63 is a motion vector and the mode signal of the block from the discrimination circuit 6 and SC.
A MIX circuit that synthesizes the SC detection signal from the detection circuit 51, and a second switch circuit 64 that switches prediction blocks.

Next, the operation will be described. The motion-compensated prediction is performed in the form shown in FIG. 4, for example, and is completed in four fields. The digital video signal input from the input terminal 1 is stored in the image memory 60. The image memory 60 is composed of a memory for at least two fields, and while storing the video signal of the field in one side, blocking the video data for scene change detection or processing from the other to a predetermined size and outputting it.

That is, a digital video signal is first sent from the image memory 60 to the SC detection circuit 61, and the presence or absence of a scene change is detected by, for example, obtaining the video feature from the set parameters. After that, the digital video signal from the other output of the image memory 60 is, for example, n [pixel] × m [line].
It is blocked and output in the size of (m and n are positive integers). The size of m [pixel] × n [line] is a block size for performing a two-dimensional orthogonal transformation, and is a block size of a prediction block by motion compensation prediction.

The error block, which is the difference between the input block just blocking the original image output from the image memory 60 and the prediction block motion-compensated by the subtractor 3, is input to the first switch circuit 62. The input block and the error block are input to the original image power calculation circuit 5 and the error power calculation circuit 4 in order to obtain the power of each block. The original image power calculation circuit 5 calculates the AC power of the input block, and the error power calculation circuit 4 calculates the power of the error block. The calculated AC power of the input block and the calculated power of the error block are input to the determination circuit 6. When the power of the error block is smaller than the power of the input block, the discrimination circuit 6 outputs the prediction mode signal,
If the power of the input block is smaller than the power of the error block, the intra mode signal is output to the first switch circuit 62, the MIX circuit 63, and the second switch circuit 64 as a mode signal, respectively.

The first switch circuit 62, to which the input block and the error block are input, outputs either one of the blocks as an encoding block. Therefore, the first switch circuit
62 receives the scene change detection signal from the SC detection circuit 61 and the mode signal from the discrimination circuit 6 to determine the mode of the switch, and outputs either the input block or the error block as the coding block. The switching state at this time is shown in FIG. Since the process of motion compensation prediction is completed in four fields as shown in FIG. 4, in the normal mode, the intra field is the first field, and then the prediction field is three fields from the second field to the fourth field. It is a mode in which the intra field continues, such as the first field.

The presence / absence of SC detection in FIG. 42 is a signal indicating that the scene change detection signal from the SC detection circuit 61 detects a scene change, and indicates that there is no scene change. The discrimination mode is an output from the discrimination circuit 6 and is the mode signal described above. It should be noted that X in the drawing means that regardless of whether or not the SC is detected, regardless of the determination mode. As shown in FIG. 42, the first switch circuit 62 determines a selected block and outputs the selected block as a coding block.

The coding block selected and output by the first switch circuit 62 is two-dimensionally orthogonally transformed by the DCT circuit 8. Then, the orthogonally transformed data is subjected to weighting processing (weighting processing), threshold processing (threshold processing), etc. in the quantization circuit 9, and is quantized to a predetermined number of bits in each sequence. The data quantized by the quantization circuit 9 is converted into a code suitable for the transmission line 11 by the first encoding circuit 10 and output to the transmission line 11. The data quantized by the quantization circuit 9 is also input to the local decoding loop 20 for performing motion compensation prediction. The data input to the local composite loop 20 is first dequantized by the dequantization circuit 12, subjected to an inverse weighting process, etc., and then subjected to the inverse orthogonal transform by the inverse DCT circuit 13. The decoded block which is the output of the inverse DCT circuit 13 is added to the prediction block pixel by pixel in the adder 14 to form a reproduced image. The prediction block used at this time is the same as that used in the subtractor 3. The block which has become the reproduced image by the adder 14 is written in a predetermined position of the image memory 15.

The image memory 15 has a different required memory amount depending on the prediction method. Assuming that it is composed of a plurality of field memories, the output block restored by the local decoding loop 20 is accumulated at a predetermined position. The image accumulated at this time is used as the data of the search range of the motion compensation prediction. From the image memory 15 to the MC circuit 16, a block that is a search range for motion detection that is reconstructed from the past output block and cut out from the reconfigured screen is output. The size of the search range block for motion detection is i
[Pixel] × j [line] (i ≧ m, j ≧ n: i, j is a positive integer). The MC circuit 16 receives the search range data for motion compensation prediction from the image memory 15 and the input block from the image memory 60 as reference data, and extracts a motion vector.

The motion vector extracted by the MC circuit 16 is
It is input to the MIX circuit 63, and is combined with the mode signal determined by the discrimination circuit 6 and the SC detection signal from the SC detection circuit. The combined signal is transmitted by the second encoding circuit 18 to the transmission line 11
Is converted into a code suitable for, and output to the transmission line 11 together with the corresponding coded block. Further, the MC circuit 16 outputs a signal which is block-shaped as a prediction block in the same size (m [pixel] × n [line]) as the input block from the search range. The prediction block output from the MC circuit 16 is generated from past image information. This prediction block is input to the second switch circuit 64, and the field currently processed, the mode signal of the decoding block, S
It is output according to the SC detection signal from the C detection circuit 51.
A prediction block is output from one output of the second switch circuit 54 to the subtractor 3 in accordance with the processing field and SC detection signal. A prediction block is output from the other output according to the mode signal of the decoding block at that time, the SC detection signal, and the processing field.

This motion compensation prediction process is shown in FIG. Figure 43
Then, it is assumed that there is a scene change between the second field F2 and the third field F3. Since there is no scene change in the first field F1 to the second field F2, the second field F2 is predicted from the first field F1. Second,
When a scene change between the third fields F2 and F3 is detected, the third field F3 becomes an intra field like the first field F1. The fourth field F4 is then predicted from the third field F3.

It should be noted that no prediction is made from the video past the scene change. When the motion compensation prediction process of the fourth field F4 is completed, the motion compensation prediction process is performed again with the next field as an intra field.
Therefore, after the motion compensation prediction process starts, an intra field always appears every four fields, and when a scene change occurs, the intra field also exists during the motion compensation process.

The operation of the tenth embodiment will be summarized using the flowcharts of FIGS. 44 and 45. Figure 44 is an example
FIG. 45 is a flowchart showing the overall operation of 10, and FIG. 45 is a flowchart showing the contents of the predictive field processing of step S406 in FIG.

First, the field number indicating the field in the motion compensation processing unit is set to 0 (step S40).
1). The setting of this field number is the same as that of the third embodiment, and since the motion compensation processing is just started right now, the first processing field is always the first field and the intra field in the motion compensation processing unit.
In 01, the field number fn is set to 0. The scene change detection flag Cfn, which is a flag for determining the presence or absence of a scene change, is set to 0 for initialization in step S401.

Next, the presence or absence of a scene change is detected by comparing the characteristics of the input image and the past image with a certain parameter, for example (step S402). For example, the scene change is detected by comparing the variance of the pixel values of some predetermined areas of the past image with the variance of the pixel values of the predetermined area of the currently processed image. When a scene change is detected, the scene change detection flag Cfn = 1 is set, and when no scene change is detected, the scene change detection flag Cfn = 0 is set.

Next, whether the field number fn = 0 or not,
That is, it is determined whether the first field in the motion compensation prediction processing unit is an intra field (step S40).
3). At this time, if fn = 0, this field is processed as an intra field (step S405), and fn ≠
If it is 0, the process proceeds to the next step S404. It is determined whether or not the scene change detection flag Cfn = 0, that is, whether or not there is a scene change between the processing field and the reference image necessary for encoding the field by motion compensation prediction (step S404).

If Cfn = 0, there is no scene change, and the field currently used for processing is processed as a predictive field (step S406), and Cfn = 1.
If so, there is a scene change, so the field currently being processed is processed as an intra field (step S405). Therefore, a scene change is detected even in the motion compensation prediction processing unit even if fn = 0 and if Cfn = 1, the processing of that field is processed as an intra field.

After each field is processed, the field number is incremented so that the field number fn points to the next field (step S407). Note that such field numbers can be controlled by signals from a microcomputer or the like in actual hardware.

Subsequently, it is determined whether or not the field number indicating the next field is a numerical value indicating the field in the motion compensation processing unit (step S40).
8). A number that does not indicate a field in the motion compensation processing unit. For example, in the example of FIG. 4, the processing unit of motion compensation prediction is completed in four fields, and the field number fn of the intra field is set to 0, so fn If it is a number such as = 4, it means that a series of motion compensation prediction units has ended, and if fn <4, it is determined that the next field is still within the motion compensation processing unit, and the next field processing is performed. It is performed again from the detection of the scene change.

When the series of motion compensation prediction processing units is completed, it is determined whether or not the processing of all desired fields is completed (step S409). This is determined by, for example, whether or not the end switch of this high-efficiency encoder is activated. If the next field is to be processed, the variable is initialized and the scene change is detected again for encoding the next motion compensation prediction processing unit. If the operation of the high-efficiency encoder is finished, the encoding is finished.

Next, the predictive field processing (step S406 in FIG. 44) in the tenth embodiment will be described with reference to the flowchart in FIG. The field determined to be processed as the prediction field in step S404 in FIG. 44 is divided into blocks of a predetermined size m [pixel] × n [line] in the processing field (step S45).
1). The block divided into the size of m × n is motion-compensated and predicted (step S452), and its error power P1 is calculated from the error block which is the difference in pixel unit between the predetermined region of the past image and the block now divided. Yes (Step S45
3). Further, the original image AC power P2 in the state of the block that is still in the block state is calculated (step S454).

The magnitudes of the calculated electric powers P1 and P2 are compared (step S455). If the error power P1 is smaller than the original image AC power P2, the error block (the difference value of the motion-compensated prediction block) is selected (step S4).
56) On the other hand, if the error power P1 is larger than the original image AC power P2, the input block (the original image that has been blocked)
Is selected (step S457). Each selected block is subjected to orthogonal transformation (step S458) and then quantized to a predetermined number of bits set in each sequence (step S459).

For example, in the case of orthogonal transform such as DCT, quantization is performed so that a large number of bits are normally assigned to low-order sequences among DC and AC, and a small number of bits are assigned to high-order sequences of AC. Is done. The quantized data is converted into a code suitable for transmission (step
S460), the encoded data is transmitted (step S461).
Further, it is determined whether or not the processing for one field is completed by counting the number of processing blocks (step S462). 1
If the process in the field is not completed, the block process is performed again. Then, if the processing of all the blocks in one field is completed, the processing of the prediction field is completed.

In the tenth embodiment, as shown in FIG. 43, when a scene change occurs in the motion compensation prediction process, the field immediately after the scene change is set to the intra field to improve the subjective evaluation of the image immediately after the scene change. Can be made

Example 11. In the tenth embodiment, as shown in FIG. 43, even if the scene change occurs in the motion compensation prediction processing process and the field immediately after that occurs in the intra field, the temporal constraint length of the motion compensation processing process is fixed at 4 fields. That is, after the motion compensation prediction process starts, an intra field appears every 4 fields,
When a scene change occurs, the intrafield also exists during the motion compensation process. This is a structure in which the prediction field is replaced with an intra field.

In the eleventh embodiment, when a scene change occurs as shown in FIG. 46, and the field immediately after that occurs as an intra field, the intra field becomes the leading field of a new motion compensation process. That is, the time constraint length of the motion compensation process is variable. Normally, for example, as shown in FIG. 46, the temporal constraint length of the motion compensation processing process is set to 4 fields, and when a scene change occurs in the motion compensation processing process, the field immediately after the scene change is set as a new intra field. Motion compensation prediction processing is performed in units of four fields, starting with the field. Further, if a scene change occurs in the motion compensation processing process, the field immediately after the scene change is similarly used as an intra field and the motion compensation prediction processing is performed in units of four fields with the field at the beginning.

FIG. 47 shows a flowchart of the whole of the eleventh embodiment. In FIG. 47, the parts given the same step numbers as in FIG. 44 indicate the same parts. First, step S401
The steps from step S406 are the same as in the tenth embodiment. The intra field processing and the prediction field processing in steps S405 and S406 are the same as in the tenth embodiment. The field number fn = 0 is set in order to switch the field processed as the intra field in step S405 to the motion compensation prediction processing unit having the processed field as the head field (step S490).

For example, as shown in FIG. 46, according to the tenth embodiment, the field number fn changes in order from 0 → 1 → 2 → 3 → 0 → ... Even if processed as an intra field. In the case of the eleventh embodiment, when the field is processed as an intra field even though it is not the first field in the motion compensation processing unit, the field number fn = 0 of the field is forcibly set and the field is newly motion compensated. It is the first field in the processing unit. As a result, the temporal constraint length of the motion compensation processing unit becomes variable, and if the scene change appears at a frequency shorter than the temporal constraint length of the motion compensation processing unit set at that time, the motion compensation processing is performed. The time constraint length of the unit is short but continuous. The following steps S407 to S409 are the same as in the tenth embodiment.

By doing as in the eleventh embodiment, the subjective evaluation can be improved by using the image immediately after the scene change as the intrafield. If the frequency of scene changes is longer than the temporal constraint length of the motion compensation processing unit and its absolute number is small, the number of intrafields is smaller than in the third embodiment, and the amount of information can be reduced.

Example 12. In the tenth and eleventh embodiments, the field (or frame) in which the scene change is detected is processed as an intrafield (or intraframe), but the field (or frame) is not treated as an intrafield (or intraframe). )
The reference image may be an intrafield (or an intraframe) belonging to the next motion compensation prediction processing unit.

The twelfth embodiment will be described with reference to FIG. Figure 48
FIG. 4A shows a state in which the motion compensation prediction process in the normal case is performed by the method shown in FIG. In this case, the intra fields are field F10 and field F14. Motion compensation prediction is performed using the fields F10 and F14 as the leading fields of the motion compensation prediction processing unit. Then, as shown in Figure 49 (b), a scene change now occurs between field F11 and field F12,
When a scene change is detected in F12, the field F12 to the last field of the motion compensation prediction processing unit including the field F12, in this case, the field up to F13 is combined into the next motion compensation prediction processing unit, and the fields F12 and F13 are Motion compensation prediction is performed using the intra field belonging to the next motion compensation prediction processing unit as a reference image.
In the next motion compensation prediction processing unit combined at this time, the normal motion compensation prediction processing and the motion compensation prediction processing of the field added above are performed.

Example 13. In the twelfth embodiment, the processing unit of the motion compensation prediction may be longer than that in the normal case. Example
At 13, in the field (or frame) in which the scene change is detected, the motion compensation prediction process is performed for P field (or P frame) which is the length of a normal motion compensation prediction processing unit.

Example 13 will be described with reference to FIG. Figure 49
FIG. 4A shows a state in which the motion compensation prediction process in the normal case is performed by the method shown in FIG. In this case, the intra fields are field F10 and field F14. Motion compensation prediction is performed using the fields F10 and F14 as the leading fields of the motion compensation prediction processing unit. Figure
As shown in 49 (b), now the scene change is field F1
It occurs between 1 and field F12, and when a scene change is detected in field F12, the four fields from field F12 where the scene change is detected (because the motion compensation prediction processing unit is four fields) are the processing units for motion compensation prediction. Normally, the field F14 that was the intra field in the first field of the next motion compensation prediction processing unit
Is set as the intrafield in the motion compensation processing unit at that time, and the motion compensation prediction processing is performed. Then, when the motion compensation prediction process for four fields from the field F12, that is, the field F15 is completed, the original normal motion compensation prediction process is performed from the field F16.

Example 14. Although the switching of the scene change is described in the third to thirteenth embodiments, since the reference image is switched according to the number of the forced intra modes of the block, a large number of the forced intra modes appear. A similar image can be used to display a reference image in the same way when an unpredictable image, that is, an object that did not exist up to one field ago or an object that existed up to one field ago suddenly appears in the field or disappears suddenly from the field. It is possible to switch.

Example 15. In the third to thirteenth embodiments, for example, the motion compensation prediction process as shown in FIG. 4 is switched to the motion compensation prediction process as shown in FIG. 29. The motion compensation prediction process may be performed, and the process is switched to the motion compensation prediction process in which the amount of generated information decreases after the scene change is detected and before the switching as shown in FIG. 29, for example.

Example 16. Although the third to fifteenth embodiments have described the motion compensation prediction process in units of four fields, the motion compensation prediction process may not be performed in units of four fields and can be performed with an arbitrary number of fields that can perform the motion compensation prediction process.

In the third to sixteenth embodiments, even if a scene change occurs in the motion compensation prediction processing unit as shown in FIG. 50, for example, as shown in FIG. The reference image is switched so that it is not affected by the scene change etc. as much as possible, and the video immediately after the scene change is used as the reference image for motion compensation prediction. By not using the field of 2 as a reference image for motion compensation prediction, it is possible to suppress the increase in the code amount due to a scene change to the minimum and to transmit without deteriorating the image quality.

When motion compensation prediction is performed with a normal scene change in between, the amount of information in the predicted image increases. Therefore, if the field is processed as an intra image with the same amount of information as that amount, the subjective evaluation of the image is improved. By detecting a scene change, intra-field coding and intra-frame coding are performed on the image immediately after the scene change as an intra image, so that the subjective evaluation of the image immediately after the scene change can be improved. Also, when a scene change occurs, the image immediately after that is treated as an intra image, and the intra image is used as the first image to perform motion compensation prediction, so that the number of intra images generated can be reduced and the amount of generated information can be reduced. Can be reduced.

Example 17 FIG. 51 is a block diagram showing the structure of a video information recording / reproducing apparatus according to the present invention. In FIG. 51, 101 to 111 are the same as those of the conventional device in FIG. 18 or 24.

The recording operation will be described. A / D converter
The video signal input to 101 is converted into a digital video signal and output to the high efficiency encoder 110. In the high-efficiency encoder 110, the autocorrelation of video information, the human visual characteristics,
Information is compressed (details will be described later) by reducing the redundancy using the bias of data generation frequency. The output of the high efficiency encoder 110 is input to the error correction encoder 102,
An error correction code for correcting a transmission path error in recording / reproduction is added.

Since high-density recording is performed and even a small error in compressed information has a wide range of influence, a code having a high error correction capability and a small amount of added information is selected. The data to which the error correction code is added is modulated by the modulator 103 into a recording signal suitable for the magnetic head 106 and the magnetic tape 105. The modulator 103 also suppresses the DC component and the low frequency component for azimuth recording, adds a tracking signal to assist the tracing of the magnetic head 106, and the like. The recording signal modulated by the modulator 103 is the magnetic head 106.
Through the magnetic tape 105. The magnetic head 106 is mounted on the rotary head drum 104. When the drum 104 rotates, the magnetic head 106 also rotates, and the magnetic tape 105 is recorded on the magnetic tape 105 by so-called heli-cal scanning.

Next, the reproducing operation will be described. The signal recorded on the magnetic tape 105 by the helicopter scan is picked up by the magnetic head 106 mounted on the rotary head drum 104 and demodulated by the demodulator 107. The demodulated signal is subjected to error detection and error correction by the error correction decoder 108. The error-corrected data is decompressed by the high-efficiency decoder 111 and converted from the compression code into the original digital video signal. The restored digital video signal is a D / A converter
At 109, it is converted into an analog video signal and output.

52 and 53 show an example of the tape format in the seventeenth embodiment. Video information of 4 fields ({72
0 + 360 x 2} x 480 x 4/2 = 11.06M bits) is about 1.3M
It is compressed and encoded into bits, and divided into 10 tracks and recorded together with audio signals, error correction codes, etc. In this case, the azimuth type guard bandless recording has an areal recording density of about 2.5 μm ² / bit.

FIG. 54 shows the high-efficiency encoder 110 shown in FIG.
3 is a block diagram showing the internal configuration of FIG. In FIG. 54, 30
1 is a subtractor that outputs the difference between the input original signal and the predicted signal,
302 is a first switch that selects the input original signal and the output of the subtractor 301; 303 is a DCT circuit that performs orthogonal transformation of DCT;
304 is a quantizer that quantizes the data to be encoded, and 305 is a variable length encoder that removes statistical data redundancy by assigning short codes to frequently-used data.

Reference numerals 306 to 311 constitute a local decoder for obtaining a prediction signal, 306 is an inverse quantizer for returning quantized data, 307 is an inverse DCT circuit for performing inverse DCT, and 308 is a prediction signal. And the difference signal are added to restore the original signal, 309 is the image memory that stores the locally decoded video data, 310 is the motion compensation prediction that detects the motion of the input original signal and outputs the next prediction data The circuit, 311 is a second switch for switching the data input to the adder 308.

Next, the operation of the high efficiency encoder 110 will be described. The first field of the recording unit block is encoded as an intra field that does not use inter-frame prediction. The upper side of the first switch 302 is selected, and the input digital video signal is orthogonally transformed by the DCT circuit 303.
The converted data is quantized by the quantizer 304, coded into a variable length code such as Huffman code by the variable length coder 305, and output. At the same time, the quantized data is inversely quantized by the inverse quantizer 306 and input to the inverse DCT circuit 307. In the inverse DCT circuit 307, the orthogonally transformed data is inversely transformed into the original image data and output to the adder 308.
In the intra field, the upper side of the second switch 311 is also selected, and therefore one input of the adder 308 becomes zero, so that the output of the inverse DCT circuit 307 remains as it is in the image memory.
309 is entered and stored.

Inter-plane prediction is used for encoding the next field. In the face-to-face prediction, the lower side of the first and second switches 302 and 311 is selected. The input digital video signal is
It enters into the subtractor 301 and the motion compensation prediction circuit 310. The motion compensation prediction circuit 310 compares the stored image with the input image, and outputs the motion vector of the input image and the predicted image used for predictive coding. The subtractor 301 calculates the difference between the input image and the predicted image, and outputs it as the DCT as the prediction error signal.
Output to circuit 303. The prediction error signal has a smaller amount of information as the prediction accuracy is higher than that of the raw image signal. For example, if it is a completely still image, its error signal becomes zero.

The data input to the DCT circuit 303 is the same as that of the first field, and the DCT circuit 303 and the quantizer 30
The orthogonal transform and the quantization are respectively performed in 4, and the variable length coder 305 further transforms and outputs the variable length code. on the other hand,
The quantized data is passed through the inverse quantizer 306 to the inverse DCT
It is sent to the circuit 307 and, after receiving the inverse quantization and the inverse orthogonal transform, enters the adder 308. The other input of adder 308 is
The prediction image used when the prediction error is calculated is input, and the output of the adder 308 is the same as the input image. The output of the adder 308 is stored in the image memory 309. Similarly, up to n fields are encoded thereafter.

FIG. 55 shows an example of changes in the amount of data generated for each frame. In this example, it can be seen that the amount of information is increased by inserting an intra frame that does not use inter-frame prediction every eight frames. Further, FIG. 56 shows an example of the recording information of each field and the writing relationship to the track. In this example, 4-field data is recorded on 10 tracks. The data amount of one field does not have to be an integral multiple of the recording capacity of the track.

Example 18. In Example 17, the data of 4 fields was recorded on 10 tracks, but it is not necessary to record it on 10 tracks each time, and it may be recorded on 8 or 6 tracks depending on the amount of information to be recorded. May be.

As described above, in the seventeenth and eighteenth embodiments, signals of a plurality of fields or frames are collectively recorded on a predetermined number of tracks as one recording unit. Therefore, if a predetermined number of tracks are reproduced, Since all the recorded fields can be reproduced, special reproduction and editing required by the VTR can be supported. In addition, since the number of tracks to be recorded is selected according to the amount of information to be recorded, no unnecessary tracks are generated and recording / reproduction can be performed for a long time. Further, since it is not necessary to match the information to be recorded with the recording capacity of each track, there is no waste generated for each track, and efficient recording can be performed. Furthermore, since there is an intra image that does not necessarily use the inter-plane prediction in each recording unit, a restored image can be easily obtained during special reproduction such as speed search. In addition, the amount of information to be recorded can be reduced as compared with a predicted image using inter-plane prediction.

[0175]

As described above in detail, the high-efficiency coding apparatus according to the present invention creates an intra field (or intra frame) in which motion compensation is not performed for every n fields (or n frames), and other fields ( (Or frame) can reduce the hardware scale by performing motion compensation prediction with the intra field (or intra frame).

Another high-efficiency coding apparatus according to the present invention sets a reference image by using a method fixed to a certain degree for a normal video without scene change, and sets the reference image in the process of motion compensation prediction. When a scene change occurs,
By switching the reference images so as to suppress the increase in the amount of generated information as much as possible, the second problem described above is solved, the generated information amount can be suppressed, and the S / N ratio of the video can be suppressed while suppressing the increase in hardware. Can be kept.

Still another high-efficiency coding apparatus according to the present invention sets a reference image using a method fixed to some extent for a normal video without scene change, performs motion compensation prediction, and then performs the motion compensation. When a scene change occurs in the process of prediction, the video immediately after the scene change is intra-field (or intra-frame) encoded as an intra-field (or intra-frame) to prevent deterioration of the video quality after the scene change. It has an effect that can be suppressed as much as possible.

The video information recording / reproducing apparatus according to still another aspect of the present invention records the signals of a plurality of fields (or frames) together as one recording unit on a predetermined number of tracks, so that the VTR is specially required. This has the effect of being compatible with playback and editing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a digital VTR.

FIG. 2 is a block configuration diagram showing a conventional motion compensation prediction processing device.

FIG. 3 is a diagram showing a block selection operation in a conventional motion compensation prediction processing device.

FIG. 4 is a diagram showing a field relationship in motion compensation prediction processing.

FIG. 5 is a diagram showing a field relationship in a motion compensation prediction process.

FIG. 6 is a diagram showing the code amount and S / N in the case of conventional motion compensation prediction.

FIG. 7 is a diagram showing a transition of the information amount for 5 seconds when the reference image is not switched.

FIG. 8: S / for 5 sec when the reference image is not switched
It is a figure which shows the change of N.

FIG. 9 is a diagram showing a tape format in the 8 mm video standard.

FIG. 10 is a diagram showing a format of one track in the 8 mm video standard.

FIG. 11 is a diagram showing a winding state of a rotary head drum and a magnetic tape used in 8 mm video.

FIG. 12 is a diagram showing frequency allocation of each signal in the 8 mm video standard.

FIG. 13 is a block diagram showing a configuration of a conventional video information recording / reproducing apparatus.

FIG. 14 is a block diagram showing a configuration of a conventional video information recording / reproducing apparatus.

15 is a timing chart showing a phase relationship between a head switching pulse signal and an input video signal in the video information recording / reproducing apparatus shown in FIGS. 13 and 14.

16 is a waveform diagram showing a video signal processed by a gate circuit in the video information recording / reproducing apparatus shown in FIGS. 13 and 14. FIG.

FIG. 17 is a waveform diagram showing a time-axis multiplexed signal in the video information recording / reproducing apparatus shown in FIGS. 13 and 14.

FIG. 18 is a block diagram showing the configuration of another conventional video information recording / reproducing apparatus.

FIG. 19 is a diagram showing a tape format of a D1 system and D2 system VTR.

FIG. 20 is a diagram showing the overall specifications of a D1 system and D2 system VTR.

FIG. 21 is a diagram showing tape format specifications of a D1 system and D2 system VTR.

FIG. 22 is a diagram showing running system specifications of a D1 system and D2 system VTR.

[Fig. 23] Fig. 23 is a diagram showing a pixel range in which a D1 system VTR and a D2 system VTR are recorded.

FIG. 24 is a block diagram showing a configuration of a communication device of a high efficiency coded video information compression system.

FIG. 25 is a diagram illustrating a buffer operation of the high efficiency code communication device.

[Fig. 26] Fig. 26 is a block diagram illustrating a configuration of a high-efficiency encoding device according to the present invention.

[Fig. 27] Fig. 27 is a diagram illustrating a field relationship in a motion compensation prediction process.

[Fig. 28] Fig. 28 is a block diagram illustrating the configuration of another high efficiency encoding device of the present invention.

[Fig. 29] Fig. 29 is a diagram illustrating a field relationship in a motion compensation prediction process.

FIG. 30 is a diagram showing a simulation result in the case where a scene change exists.

FIG. 31 is a diagram showing a simulation result when there is no scene change.

FIG. 32 is a block diagram showing the configuration of still another high efficiency encoding device of the present invention.

33 is a flowchart of the operation of the high efficiency encoding device shown in FIG. 32.

34 is a flowchart of intrafield processing in FIG. 33.

35 is a flowchart of the predictive field processing in FIG. 33.

[Fig. 36] Fig. 36 is a diagram illustrating a transition of the information amount for 5 seconds when the reference image is switched.

[Fig. 37] S / for 5 seconds when the reference image is switched
It is a figure which shows the change of N.

38 is a flowchart of another predictive field process in FIG. 33.

FIG. 39 is a flowchart of yet another predictive field process in FIG. 33.

40 is a flowchart of reference image switching determination processing in FIG. 39.

FIG. 41 is a block diagram showing the configuration of still another high efficiency encoding device according to the present invention.

42 is a diagram showing an operation of block selection in the high efficiency encoding device shown in FIG. 41. FIG.

[Fig. 43] Fig. 43 is a diagram illustrating switching between a reference image and an intrafield in the high efficiency encoding device illustrated in Fig. 41.

FIG. 44 is a flowchart of the operation of the high efficiency encoding device shown in FIG. 41.

45 is a flowchart of predictive field processing in FIG. 44.

[Fig. 46] Fig. 46 is a diagram illustrating another switching between the reference image and the intra field in the high efficiency encoding device illustrated in Fig. 41.

FIG. 47 is a flowchart of another operation of the high efficiency encoding device shown in FIG. 41.

[Fig. 48] Fig. 48 is a diagram illustrating field relationships in a motion compensation prediction process.

[Fig. 49] Fig. 49 is a diagram illustrating field relationships in a motion compensation prediction process.

FIG. 50 is a diagram showing switching of reference images.

FIG. 51 is a block diagram showing a configuration of a video information recording / reproducing apparatus of the present invention.

FIG. 52 is a diagram showing an example of a tape format according to the present invention.

FIG. 53 is a diagram showing an example of a tape format according to the present invention.

54 is a block diagram showing an internal configuration of the high efficiency encoder in FIG. 51. FIG.

FIG. 55 is a diagram showing an example of changes in the amount of data generated for each frame.

FIG. 56 is a diagram for explaining the relationship between the recording information of each field and the writing on the track according to the present invention.

[Explanation of symbols]

 2 Blocking circuit 4 Error power calculation circuit 5 Original image power calculation circuit 6 Discrimination circuit 7 First switch circuit 16 MC circuit 19 Second switch circuit 30 Motion compensation prediction circuit 31 Judgment unit 32 First switch 33 Orthogonal transformation circuit 34 Quantization circuit 35 Second switch 36 Inverse quantization circuit 37 Inverse orthogonal transformation circuit 40 Judgment device 50 Mode counter 51 Direction switching circuit 52 Image memory 60 Image memory 61 SC detection circuit 62 First switch circuit 64 Second switch circuit 103 Modulator 107 Demodulator 110 High-efficiency encoder 111 High-efficiency decoder

 ─────────────────────────────────────────────────── ─── Continuation of front page (31) Priority claim number Japanese Patent Application No. 4-43075 (32) Priority date Hei 4 (1992) February 28 (33) Country of priority claim Japan (JP) (72) Inventor Ken Onishi 1st Baba Institute, Nagaokakyo City, Kyoto Prefecture Mitsubishi Electric Co., Ltd. Electronic Products Development Laboratory (72) Inventor Hidetoshi Mishima 1st Baba Institute, Nagaokakyo City Kyoto Prefecture Mitsubishi Electric Corporation Electronic Products Development Laboratory

Claims (24)

[Claims] 1. A means for dividing a digitized video signal into blocks of a predetermined size for encoding, and a motion compensation prediction for every n fields or n frames (n is an arbitrary integer of 2 or more). A non-intra field or intra frame, and for each subsequent n-1 field or n-1 frame, a prediction means for performing motion compensation prediction with the intra field or intra frame is provided. Characterizing high-efficiency coding device. 2. A means for dividing a digitized video signal into blocks of a predetermined size for encoding, and a motion compensation prediction for every n fields or n frames (n is an arbitrary integer of 2 or more). A non-intra field or intra frame, and for the subsequent n-1 field or n-1 frame, a prediction means for performing motion compensation prediction with the intra field or intra frame, and a motion compensation prediction And a means for comparing the amount of information in each block between the case where motion compensation prediction is not performed and the case where motion compensation prediction is not performed as compared with the case where motion compensation prediction is performed. When the amount of information of the block becomes small, the selection method to select the forced intra mode as the coding mode of the block A high-efficiency coding device comprising: a stage. 3. Encoding means for dividing a digitized video signal into blocks of a predetermined size for encoding,
An intra field or intra frame that does not perform motion compensation prediction is created for each field or n frames (n is an arbitrary integer of 2 or more), and for each subsequent n-1 field or n-1 frame, a respective block is created. On the other hand, a prediction means for performing motion compensation prediction with an intra field or an intra frame, and a means for comparing the amount of information in each block with and without motion compensation prediction for each block are provided. The prediction means does not perform motion-compensated prediction for a field or frame in which the amount of information in the block is smaller when motion-compensated prediction is not performed than when the motion-compensated prediction is performed.
A high-efficiency coding apparatus, wherein the coding means is configured to perform coding as a forced intra-field or a forced intra-frame. 4. A coding means for dividing a digitized video signal into blocks of a predetermined size and coding the blocks.
An intra field or intra frame that does not perform motion compensation prediction is created for each field or n frames (n is an arbitrary integer of 2 or more), and for each subsequent n-1 field or n-1 frame, a respective block is created. On the other hand, a prediction means for performing motion compensation prediction with an intra field or an intra frame, and a means for comparing the amount of information in each block with and without motion compensation prediction for each block are provided. The prediction means does not perform motion-compensated prediction for a field or frame in which the amount of information in the block is smaller when motion-compensated prediction is not performed than when the motion-compensated prediction is performed.
The encoding means performs encoding as a forced intra field or a forced intra frame, and the predicting means,
A high-efficiency coding apparatus configured to perform motion-compensated prediction for the forced intra-field or the forced intra-frame for at least the n-1 field or the n-1 frame following the forced intra-field or the forced intra-frame again. .. 5. A coding means for dividing a digitized video signal into blocks of a predetermined size for coding, a prediction means for performing motion compensation prediction for each block, and a motion compensation prediction processing step. A detection unit that detects that a scene change has occurred; and a unit that switches a field or frame that serves as a reference image for motion compensation prediction in a direction in which the amount of code generated when a scene change occurs decreases. High efficiency coding device. 6. The detecting means is configured to detect the occurrence of a scene change by using the number of blocks in the prediction mode or the intra mode selected in the field or the frame. Item 5. The high efficiency encoding device according to Item 5. 7. The detection means uses the ratio of the number of blocks processed in the prediction mode or the number of blocks processed in the intra mode to the predetermined number among the predetermined number of blocks to detect that a scene change has occurred. The high efficiency encoding device according to claim 5, wherein the high efficiency encoding device is configured to detect. 8. A coding means for dividing a digitized video signal into blocks of a predetermined size for coding, a prediction mode for performing motion compensation prediction for each block, and an intra for which motion compensation prediction is not performed. Means for switching between modes, and when a scene change occurs in the motion compensation prediction processing process, the scene change is detected by a signal generated from the prediction mode and the intra mode, and the motion compensation prediction is performed in the direction in which the generated code amount decreases. And a means for switching a field or a frame serving as a reference image of the high efficiency encoding device. 9. The high-performance apparatus according to claim 8, wherein the scene change is detected by using the number of blocks of the prediction mode or the intra mode selected in the field or the frame. Efficiency encoder. 10. A structure for detecting the occurrence of a scene change by using a ratio of the number of blocks processed in the prediction mode or the number of blocks processed in the intra mode among the predetermined number of blocks and the predetermined number. The high efficiency encoding device according to claim 8, wherein 11. Encoding means for dividing a digitized video signal into blocks of a predetermined size for encoding.
Prediction means for performing motion-compensated prediction for each block, detection means for detecting that a scene change has occurred in the process of motion-compensated prediction processing, and the field or frame immediately after the detected scene change must be the reference image for motion-compensated prediction. And a means for switching the reference image so that the high efficiency encoding device. 12. The detecting means is configured to detect that a scene change has occurred, by using the number of blocks in a prediction mode or an intra mode selected in a field or a frame. Item 11
The high-efficiency coding device described. 13. The detection means uses the ratio of the number of blocks subjected to prediction mode processing or the number of blocks subjected to intra mode processing among the predetermined number of blocks to the predetermined number to detect that a scene change has occurred. 12. The high efficiency encoding device according to claim 11, wherein the high efficiency encoding device is configured to detect. 14. A means for dividing a digitized video signal into blocks of a predetermined size for encoding, a predicting means for performing motion compensation prediction for each block, and a scene change in a motion compensation prediction processing process. A high-efficiency coding apparatus, comprising: a detection unit that detects that a scene has occurred, and a unit that switches the reference image so that the detected field or frame before the scene change is not used as a reference image for motion compensation prediction. .. 15. A unit for dividing a digitized video signal into blocks of a predetermined size for encoding, and n fields or n frames (n is an arbitrary integer of 2 or more) as one processing unit, The scene change is provided with a means for performing motion compensation prediction processing having one field intra field or one frame intra frame therein, and a detection means for detecting the occurrence of a scene change in the motion compensation processing unit. A high-efficiency coding apparatus, characterized in that the field or frame in which is detected is an intrafield or an intraframe, and a plurality of intrafields or intraframes are included in the processing unit of the motion compensation prediction process. 16. A unit for dividing a digitized video signal into blocks of a predetermined size for encoding, and n fields or n frames (n is an arbitrary integer of 2 or more) as one processing unit, The scene change is provided with a means for performing motion compensation prediction processing having one field intra field or one frame intra frame therein, and a detection means for detecting the occurrence of a scene change in the motion compensation processing unit. A high-efficiency coding apparatus, characterized in that the field or frame in which is detected is an intra-field or an intra-frame, and is set as a head field or head frame of a processing unit of new motion compensation prediction processing. 17. A unit for dividing a digitized video signal into blocks of a predetermined size for encoding, and n fields or n frames (n is an arbitrary integer of 2 or more) as one processing unit, The scene change is provided with a means for performing motion compensation prediction processing having one field intra field or one frame intra frame therein, and a detection means for detecting the occurrence of a scene change in the motion compensation processing unit. From the field or frame in which the motion compensation prediction processing unit is detected to the last field or frame of the motion compensation prediction processing unit is combined with the next motion compensation prediction processing unit, Intrafield or intraframe that is longer and belongs to the next motion-compensated prediction processing unit A high-efficiency coding apparatus, which is configured to perform motion-compensated prediction by using as a reference image. 18. A unit for dividing a digitized video signal into blocks of a predetermined size for encoding, and n fields or n frames (n is an arbitrary integer of 2 or more) as one processing unit, The scene change is provided with a means for performing motion compensation prediction processing having one field intra field or one frame intra frame therein, and a detection means for detecting the occurrence of a scene change in the motion compensation processing unit. Is used as a prediction field or a predicted frame, and the field or frame in which the scene change is detected is the n motion field or the next motion compensation prediction processing unit, and the motion compensation prediction process is performed. A high-efficiency encoder. 19. In a video information recording / reproducing apparatus for recording video information by helicopter scan recording, signals of a plurality of fields or a plurality of frames are collectively set as one recording unit,
A video information recording / reproducing apparatus characterized by recording on a predetermined number of tracks. 20. The video information according to claim 19, wherein the information amount of one field or one frame when being combined as a recording unit is not necessarily an integral multiple of the information amount that can be recorded in one track. Recording / playback device. 21. A signal of a plurality of fields or a plurality of frames to be recorded is configured such that an intra field or intra frame not using inter-frame prediction and a prediction field or prediction frame using inter-frame prediction are mixed. 21. The video information recording / reproducing apparatus according to claim 20, wherein: 22. In a video information recording / reproducing apparatus for recording video information by helicopter scan recording, signals of a plurality of fields or a plurality of frames are collectively set as one recording unit,
A video information recording / reproducing apparatus characterized by recording on a track selected from a predetermined number of tracks according to the amount of information to be recorded. 23. The video information according to claim 22, wherein the information amount of one field or one frame when being combined as a recording unit is not necessarily an integral multiple of the information amount that can be recorded in one track. Recording / playback device. 24. A plurality of fields or a plurality of frames of signals to be recorded are configured such that intra fields or intra frames that do not use inter prediction and mixed prediction fields or prediction frames that use inter prediction are mixed. 24. The video information recording / reproducing apparatus according to claim 23, wherein: