JP3284678B2 - Digital video signal recording method and recording apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ATV (Advanced T
The present invention relates to a digital video signal recording method and recording apparatus capable of recording and reproducing signals directly on a magnetic tape by a rotary head, and more particularly to improvement of variable speed reproduction.

[0002]

2. Description of the Related Art An input digital video signal is converted into a DCT (Digit) signal.
The development of a digital VTR in which a Cosine Transform is converted, compressed by variable-length coding, and recorded on a magnetic tape by a rotating head is under development. In such a digital VTR, a mode for recording a video signal of the current television system such as the NTSC system (hereinafter, referred to as an SD mode) and a mode for recording an HDTV signal (hereinafter, referred to as an SD mode).
HD mode). In the SD mode, a video signal is recorded after being compressed to about 25 Mbps. H
In the D mode, the video signal is compressed to about 50 Mbps and recorded.

Conventionally, HDTV signals are converted to digital VT signals.
When recording in R, the HDTV signal is compressed and recorded in the HD mode. However, in the case of the all-digital system such as the AD-HDTV system, the signal is compressed and transmitted.
Can record directly. As described above, when the transmitted signal is directly recorded on the digital VTR, it is not necessary to decode the HDTV signal from the transmitted signal and compress or re-encode the HDTV signal and input the HDTV signal to the digital VTR. This has the advantage of eliminating waste.

That is, ATV (Advanced Television)
With the selection of a method, a method of transmitting an HDTV (High Definition Television) signal by digitizing everything from signal processing to transmission has been proposed. AD-HDTV is one of the most promising of these systems. In the AD-HDTV system, MPEG (MovingIm), which is an international standard for moving images, is used.
The HDTV signal is compressed by image compression based on the Age Coding Experts Group, and packetized for transmission.

FIG. 20 shows a configuration of a transmission system of the AD-HDTV system. In FIG. 20, 101 is a video compression encoder, and 102 is an audio encoder. The video compression encoder 101 has an input terminal 103
Supplies an HDTV video signal. An audio signal is supplied from an input terminal 104 to the audio encoder 102.

[0006] The video compression encoder 101 compresses an input HDTV signal in accordance with the MPEG standard, which is an international standard for moving images.

That is, the video compression encoder 101
Compresses an HDTV signal using a high-efficiency coding scheme combining DCT and motion compensation. From the video compression encoder 101, as shown in FIG. 21, an intra-coded frame (referred to as an I frame), a forward predictive coded frame (referred to as a P frame), and a bidirectional predictive code Frame (referred to as B frame)
Are sent in a predetermined order. In an I frame, DCT is performed independently without using a correlation with another frame. In a P frame, an earlier I frame or P
Motion compensation prediction is performed from the frame, and the difference signal is D
CT conversion is performed. In the B frame, motion compensation prediction is performed from the preceding or succeeding I frame or P frame, and the difference signal is subjected to DCT. The period at which the I frame appears is GOP
(Group Of Picture). In this example,
(GOP = 9).

In FIG. 20, reference numeral 105 denotes a priority encoder. Priority encoder 105
Is for prioritizing the compressed HDTV signal data. An example of the priority order is shown below.

I-frame -1... I-frame 1. 1. Frame header 2. Slice header 3. macroblock address, type and quantization step DC value5. Low frequency coefficient 6. High-frequency coefficient ------------------------------------------------------------------------- P and B frames 1. Frame header 2. Slice header 3. macroblock address, type and quantization step Motion vector DC value 6. Low frequency coefficient High frequency coefficient

As described above, in the I frame, the frame header has the first priority, and the slice header, the macroblock address, the type and the quantization step, the DC value, the low frequency coefficient, and the high frequency coefficient of the I frame have the same priority. Continue. In the P and B frames, the frame header, the slice header, the macroblock address, the type and the quantization step, the motion vector, the DC value, the low frequency coefficient, and the high frequency coefficient follow in order.

Reference numeral 106 denotes a transport encoder. The transport encoder 106 converts a packet from video data, which has been prioritized by the priority encoder 105, audio data encoded by the audio encoder 104, and additional information from the input terminal 107. Generate Packets include high-priority packets and low-priority packets. A high priority packet is called an HP (High Priority) packet, and a low priority packet is called an SP (Standard Priority) packet. The ratio between HP packets and SP packets is 1
It is four. In a normal image, the data from the header of the I frame to the low frequency coefficient and the data from the header of the P and B frames to the motion vector are transmitted in the HP packet. HP packets are transmitted on carriers with high output power. SP packets are transmitted on a low output power carrier.

FIG. 22 shows the structure of a packet. As shown in FIG. 22A, the packet length of the transmitted packet is 148 bytes. A sync is provided at the head of this packet, and subsequently, a transmission data and parity for error correction are added.

FIG. 22B shows details of the transmission data. A service type ST is provided at the head of the transmission data. As shown in FIG. 23, the service type ST includes information P indicating whether the packet is a high-priority HP packet or a low-priority SP packet, identification information ID such as video or audio, and 0 to 0. The counter CC counting to 15 is included.

Following the service type ST, an after header AH is provided. FIG. 24A shows an after header of an HP packet, and FIG. 24B shows an after header of an SP packet. The after header AH of the HP packet includes a slice start pointer indicating the first bit of the input point of the transfer data, a frame type, a frame number, a slice number in the frame, and a quantization factor. The after header AH of the SP packet includes the start pointer of the macroblock, the frame type, the frame number, and the macroblock number in the frame.

In FIG. 20, reference numeral 108 denotes a channel modulator. H generated by the transfer encoder 106
The P packet and the SP packet are supplied to the channel modulator 108. Channel modulator 108
Then, the HP packet and the SP packet are modulated using two carriers. The output of the channel modulator 108 is output from the output terminal 109.

In the AD-HDTV system, an HDTV signal can be transferred at 17.4 Mbps by image compression as described above. This is lower than the recording rate (about 25 Mbps) in the SD mode of the digital VTR. Therefore, a signal sent by the AD-HDTV system can be directly recorded in the SD mode of the digital VTR. As described above, when the transmitted signal is directly recorded on the digital VTR, there is no need to decode the HDTV signal from the transmitted signal and input it to the digital VTR.
Eliminates hardware waste. Further, since recording can be performed in the SD mode, the recording time can be extended.

However, if the AD-HDTV signal is directly recorded on the digital VTR in the SD mode as described above, there arises a problem that good variable-speed reproduction cannot be performed for the following reasons.

That is, as described above, the AD-HDTV
In the system, compression conforming to the MPEG system is performed. In this method, as described above, an intra-frame coded I frame, a forward predictive coded P frame, and a bidirectional predictive coded B frame are transmitted. At the time of variable speed reproduction, data of a continuous frame cannot be obtained because the head passes over the track. If data of continuous frames cannot be obtained, data of P frames and B frames cannot be decoded. Only I-frame data encoded in the frame can be decoded. This I
Normally, all data of a frame is sent in an HP packet. Therefore, at the time of variable speed reproduction, variable speed reproduction can be performed by using only the data of the I frame of the HP packet among the data to be reproduced.

However, if the signal transmitted by the AD-HDTV is directly recorded on the digital VTR, the HD packet including the I frame cannot be sufficiently picked up at the time of variable speed reproduction. Further, it is uncertain in what positional relationship the I frame data is recorded. For this reason, data of an I frame corresponding to a specific portion of the screen may be lost during variable speed playback, and only the screen of that portion may not be updated for a while, and the image quality during variable speed playback is degraded.

Therefore, the applicant of the present application has described that the HP packet data including the I frame is redundantly recorded in a marginal area caused by the transmission rate of the ATV signal being lower than the source rate in the SD mode of the digital VTR. is suggesting. As a result, the probability that HP packet data including an I frame can be picked up at the time of variable speed reproduction is increased, and the image quality at the time of variable speed reproduction can be improved.

[0021]

By the way, in such a digital VTR, three types of configurations can be adopted as a head arrangement. That is, a configuration in which two heads having different azimuth angles are arranged 180 degrees opposite to each other, a configuration in which two heads having different azimuth angles are arranged in one position by a double azimuth head, and Different double azimuth heads are provided to face each other by 180 degrees to provide a four-head configuration.

As described above, when the HP packet data is recorded in the margin recording area, the reproducible area fixed at the time of variable speed reproduction is defined as the margin recording area, and the HP packet data is recorded in this margin recording area. . However, depending on the head arrangement, some tracks may not be traced by any of the heads, and even if HP packet data is recorded in the margin recording area of these tracks, it is not reproduced during variable speed reproduction. For this reason, the HP packet data recorded on the track that is not reproduced may be lost and the screen may be disturbed.

Accordingly, it is an object of the present invention to provide a digital video signal capable of obtaining good image quality during variable speed reproduction when an HDTV signal transmitted in an all-digital system is directly recorded, regardless of the arrangement of heads. A recording method and a recording apparatus.

[0024]

SUMMARY OF THE INVENTION The present invention provides a DCT (Diode
screte Cosine Transform) and motion compensation
To afford the recording area resulting transmission rate of the high-efficiency coding scheme signal by less than the transmission rate of the compressed current practice digital video signal, a digital video recording duplicate high packet data importance of high-efficiency coding scheme signal In the signal recording method, two pieces of high importance packet data are transmitted over substantially 2n (n is a double speed during variable speed reproduction) tracks, and one of the two high importance packet data has a first azimuth angle. On one track, the other on the second
This is a digital video signal recording method for recording on a track having an azimuth angle of.

The present invention provides a DCT (Discrete Cosine Tr)
high efficiency coding system that combines motion compensation and motion compensation <br/> In a digital video signal recording apparatus in which a signal is directly recorded on a magnetic tape, the transmission rate of the high efficiency coding signal is reduced to the current format digital video signal. spare recording area, the high efficiency caused by lower than the transmission rate of the
The packet data with high importance of the coded signal is recorded in an overlapping manner, and the two packet data with high importance are recorded in two high importance packets over approximately 2n (n: double speed in variable speed reproduction) tracks. One of the packet data is a digital video signal recording apparatus which records the data on a track having a first azimuth angle and the other data is recorded on a track having a second azimuth angle.

[0026]

The AT which is compressed and transmitted by the all digital system
When a V signal is recorded in the current television signal recording mode (SD mode) of the digital VTR, an I frame is stored in an extra area caused by the transmission rate of the ATV signal being lower than the source rate in the SD mode of the digital VTR. By recording the included HD packet data redundantly, the probability that the HD packet data including the I frame can be picked up at the time of variable speed reproduction is increased, and the image quality at the time of variable speed reproduction can be improved.

Then, the two HP packet data are spread over 36 tracks, which are approximately 2n (n is a double speed at the time of variable speed reproduction) tracks, one for the A azimuth track and the other for the B azimuth track. By recording
Good variable-speed reproduction can be performed regardless of the arrangement of the heads.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a video recording / reproducing system to which the present invention is applied. In FIG. 1, reference numeral 1 denotes a channel demodulator. AD-HDTV transmission data is input from an input terminal 2 to the channel demodulator 1. In the channel demodulator 1, the packet is demodulated from the transmission data. The transmitted packets include an HP packet for transferring data of high importance and an SP packet for transferring data of low importance.

Reference numeral 3 denotes a digital VTR. The digital VTR 3 includes an interface / format converter 4 and a recording / reproducing unit 5. The HP packet and the SP packet from the channel demodulator 1 are supplied to the transport and priority decoder 6 via the interface and format converter 4, and are also supplied to the recording / reproducing unit 5. The data transferred to the recording / reproducing unit 5 via the interface and the format converting unit 4 can be recorded on the magnetic tape by the recording / reproducing unit 5 by a rotating head. Further, the interface and format converter 4 formats the data sent to the recording / reproducing unit 5 so that when the recording data recorded by the recording / reproducing unit 5 is reproduced at a variable speed, the reproduction screen becomes good. This will be described in detail later.

The recording / reproducing section 5 has a configuration in which a digital video signal is subjected to DCT conversion and variable-length encoding, compressed, and recorded on a magnetic tape by a rotating head. The recording / reproducing unit 5 is an SD card for recording a video signal of the NTSC system or the like.
A mode and an HD mode for recording an HDTV signal can be set. When demodulating and directly recording AD-HDTV transmission data, the mode is set to the SD mode. In addition,
The source rate in the SD mode is 24.3 Mbps.

The transport and priority decoder 6 corrects the error of the transferred HP packet and SP packet, and extracts transfer data and additional data from the transferred HP packet and SP packet. In a normal image, the parts from the header of the I frame to the low frequency coefficient and the parts from the headers of the P and B frames to the motion vectors are transmitted as HP packets. Others are transmitted in SP packets.

Reference numeral 7 denotes a video expansion decoder, and reference numeral 8 denotes an audio decoder. The video expansion decoder 7 decodes the Huffman code and performs DCT inverse transform in accordance with the MPEG system, expands the transmitted data, and forms an HDTV baseband signal. The output of the transport and priority decoder 6 is supplied to the video expansion decoder 7 and the audio decoder 8. The transmitted data is expanded by the video expansion decoder 7,
An HDTV signal is formed. The HDTV signal thus formed is output from the output terminal 9. The audio data is decoded by the audio decoder 8, and the audio data is output from the output terminal 10. Further, additional information output from the transport and priority decoder 6 is output from an output terminal 11.

FIG. 2 shows a configuration of a recording system of the recording / reproducing unit 5 in a VTR to which the present invention is applied. In FIG. 2, reference numeral 21 denotes an input terminal for a video signal or an HDTV signal of the current television system such as the NTSC system.
When recording an external video signal, input terminal 2
1, a video signal of the current television system or an HDTV
A component video signal of the signal is provided. The component video signal from the input terminal 21 is supplied to an A / D converter 22, and the A / D converter 22 converts the component video signal into a digital signal.

Reference numeral 23 denotes a DCT compression circuit. The DCT compression circuit 23 compresses the input video signal by DCT transform and variable length coding. The output of the A / D converter 22 is
It is supplied to the DCT compression circuit 23 and compressed. That is, the component video signal from the A / D converter 22 is divided into blocks, shuffled, and subjected to DCT conversion. DCT-transformed data is buffered in a predetermined buffer unit. Then, the total code amount in the predetermined buffer unit is estimated, an optimal quantization table is determined so that the total code amount is equal to or less than a predetermined value, and quantization is performed using the optimal quantization table. Then, after being subjected to the variable length coding, it is framed.

A switch circuit 24 switches between recording the transmitted signal of the AD-HDTV system and recording the video signal from the input terminal 21. AD 24 is connected to the terminal 24A of the switch circuit 24 via the interface and the format converter 4 described above.
-An HDTV signal is supplied. Switch circuit 24
The terminal 24B is supplied with the output of the DCT compression circuit 23. When recording the transmitted signal of the AD-HDTV system, the switch circuit 24 is set to the terminal 24A side. When recording a video signal from the input terminal 21, the switch circuit 24 is set to the terminal 24B side.

Reference numeral 25 denotes a framing circuit. The framing circuit 25 develops the recording data into predetermined sync blocks and performs error correction coding processing.

Reference numeral 26 denotes a channel encoder. The output of the switch circuit 24 is supplied to a channel encoder 26 and modulated. The output of the channel encoder 26 is supplied to a rotary head 28 via a recording amplifier 27. A video signal or AD-H from the input terminal 21 compressed on a magnetic tape (not shown) by the rotary head 28
A DTV signal is recorded.

In such a recording system, when recording the transmitted signal of the AD-HDTV system, the switch circuit 24 is switched to the terminal 24A side. For this reason, the signal of the AD-HDTV system input via the interface and the format converter 4 is framed by the framing circuit 25 and
And is recorded on a magnetic tape by the rotary head 27.

When recording a video signal from the input terminal 21, the switch circuit 24 is switched to the terminal 24B. Therefore, the video signal from the input terminal 21 is
The data is compressed by the DCT compression circuit 23,
5, modulated by a channel encoder 26, and recorded on a magnetic tape by a rotating head 27.

At the time of recording an AD-HDTV signal, the interface and format conversion section 4 records extra data corresponding to the HP packet and also responds to the HP packet in order to improve the image quality during variable speed reproduction. Data is arranged at a position where it can be reliably picked up during variable speed playback.

That is, while the source rate in the SD mode of the digital VTR is 24.3 Mbps, A
Since the transmission rate of the D-HDTV signal is 17.4 Mbps, if the transmitted AD-HDTV signal is recorded in the SD mode, there is a margin in the recording area. Therefore, when recording an AD-HDTV signal in the SD mode in order to improve the image quality during variable-speed reproduction, data corresponding to the HP packet is redundantly recorded in this extra area. In the SD mode, data of 135 sync blocks can be recorded on one track. In AD-HDTV, H
The ratio between P packets and SP packets is 1: 4. The transmission rate of AD-HDTV is 17.4 Mbps.
And the source rate of the SD mode of the digital VTR is 2
4.38 bps. From this, the number of sync blocks occupied by the HP packet in one track is 135 × (17.4 / 24.3) × (1/5) = 19.333 (sync block), which is about 20 sync blocks. is there. The number of sync blocks occupied by SP packets of one track is 20 × 4 = 80 (sync blocks). Therefore, the remaining one of 135 sync blocks per track is 135-20-80 = 35 (sync block). Therefore, HP packets can be redundantly recorded up to 35 sync blocks per track.

That is, as shown in FIG. 3A, 135 sync blocks of data can be recorded in the video area of one track. In this example, as shown in FIG. 3B, overlapping HP areas D _HP are provided at, for example, three places in one track, and the data of the HP packet overlaps, for example, by 32 sync blocks in the three overlapping HP areas D _HP. Recorded.

At the time of variable speed reproduction, if the positional relationship between the head trace and the track is always kept the same by the servo circuit,
The reproducible area in one track is fixed. The overlapping HP area D _HP is allocated to the fixed playable area.

As shown in FIG. 4, during variable speed reproduction, the head passes over the track. As a result, a reproduced signal as shown in FIG. 5A is obtained. As shown in Figure 5B, the position H _RF where the reproduction signal is sufficiently obtained, by the positional relationship between the trace and track the head is always kept the same,
Fixed. Duplicate HP area is provided at a position H _RF where the reproduction signal can be sufficiently obtained.

The digital VTR is 1 in the SD mode.
A frame is recorded on 10 tracks. AD-HDTV
The period GOP of the I frame of the system is 9 frames.
From this, the data of one GOP cycle on average is 90
Recorded on the track. Among the data of the cycle of 1 GOP, the data necessary at the time of variable speed reproduction is only the I frame out of the I frame, the B frame, and the P frame.
There is only one frame during the OP.

By selecting an odd number having a multiple speed of 17, the overlapping HP area can be made the same for the two heads A and B. If the double speed number is 17,
If the same HP packet data is recorded over 17 tracks in the overlapping HP area, the data is always reproduced by one or two scans.

Note that the reproducible area which is fixed when reproduced at 17 × speed is also a fixed reproducible area when reproduced at 4 × and 9 × speed. Therefore, if the HP packet data is redundantly recorded in the fixed reproducible area at the 17-times speed, it can correspond to the 4-times speed and the 9-times speed.

Since one GOP cycle is 90 tracks,
The number of tracks for recording the same HP packet data is 1 G
The processing is easier if the number is set to a divisor of 90 tracks in the OP cycle. Therefore, when the double speed number is 17, the same HP
It is conceivable that the number of tracks for recording packet data is 18 tracks, which is a divisor of 90 tracks.

Assuming that the capacity of the overlapping HP area per track is 32 sync blocks, 90 capacity of one GOP cycle
The total capacity of the overlapping HP area for the track is 32 × 90 = 2880 sync blocks. When the same data is recorded over 18 tracks, the number of HP packets recorded in the overlapping HP area of 90 tracks in one GOP cycle is 2880/18 = 160 sync blocks.

The head positions of the digital VTR are, as shown in FIG. 6, a structure in which two heads 71A and 71B having different azimuth angles are arranged 180 degrees opposite to each other, as shown in FIG. A configuration in which the heads 72A and 72B of the double azimuth configuration are provided at the same position can be adopted. Further, as shown in FIG. 8, a four-head configuration in which the heads 73A and 73B having a double azimuth configuration and the heads 74A and 74B having a double azimuth configuration are arranged 180 degrees opposite to each other can be adopted. In the two-head configuration shown in FIGS. 6 and 7, the drum rotates at 9000 rpm. In the four-head configuration shown in FIG.
Rotated at 0 rpm.

When recording the same HP packet data continuously over 18 tracks, it is conceivable to record the same HP packet data on 18 consecutive tracks as shown in FIG. In FIG. 9, HP packet data recorded on the first 18 tracks during one GOP is D0, HP packet data recorded on the next 18 tracks is D1, and HP packet data recorded on the next 18 tracks is D1.
The packet data is D2, the HP packet data recorded on the next 18 tracks is D3, and the next 18
The D4 is the HP packet data recorded on the track.

FIG. 10 shows a track in which the same HP packet data is recorded on 18 consecutive tracks as described above.
This shows the trajectories of the heads 71A and 71B in the case of variable speed reproduction at 17 × speed using the heads 71A and 71B facing 180 degrees. As shown in FIG.
When the heads 71A and 71B opposed to each other by 0 degrees are used,
HP packet data D at channel A head 71A
Are reproduced, and then the HP packet data D1, D1,... Are reproduced by the B channel head 71B, and all the duplicated HP packet data can be picked up.

On the other hand, FIG. 11 shows heads 72A and 72B of double azimuth heads in which the same HP packet data is recorded on 18 consecutive tracks in such a manner as to be reproduced at 17 × speed. 72
It shows the trajectories of A and 72B. When the double azimuth heads 72A and 72B are used, as shown in FIG.
The HP packet data D0 is reproduced from both the heads 71B of the channel, but the next HP packet data D1 is not reproduced from both the heads.
This becomes packet data D2. As described above, when the double azimuth heads 72A and 72B are used,
All duplicate HP packet data is not reproduced.

Therefore, as shown in FIG. 12, two HP packet data are recorded such that the same HP packet data is allocated to tracks having the same azimuth angle in 36 tracks.

FIG. 13 shows an example in which the same HP packet data is recorded on the track having the same azimuth angle among the 36 tracks at a 17-times speed using the heads 71A and 71B opposed to each other by 180 degrees. This shows the head trajectory when performing variable speed reproduction. As shown in FIG.
When the heads 71A and 71B opposed to each other by 180 degrees are used, the HP packet data D0, D0,... Are reproduced by the head 71A of the A channel, and the HP packet data D1,. D1,
Are reproduced, and all the duplicated HP packet data can be picked up.

FIG. 14 shows double azimuth heads 72A and 72B in which the same HP packet data is recorded on tracks having the same azimuth angle out of 36 tracks, at variable speed reproduction at 17-times speed. 9 shows a head trajectory in the case. When the double azimuth heads 72A and 72B are used, as shown in FIG. 14, the HP packet data D0 is reproduced from the A channel head 71A and at the same time, the B channel head 71A is used.
The HP packet data D1 is reproduced from B, and all the duplicated HP packet data can be picked up.

As described above, when the same HP packet data is recorded on the track having the same azimuth angle in the 36 tracks, the heads 71A and 71A facing each other by 180 degrees are provided.
All the HP packet data can be picked up at the time of variable speed reproduction at 17 × speed using 1B and at the time of variable speed reproduction at 17 × speed with the double azimuth heads 72A and 72B.

In the case of four heads, since the number of rotations of the head is halved, the trajectory of the head at 17-times speed is as shown in FIG. In such a four-head configuration, if the speed is 9 times, the trajectory of the head is similar to that when a double azimuth head is used. Therefore, if the same HP packet data is recorded on tracks having the same azimuth angle among the 36 tracks, variable speed reproduction can be performed at 9 × speed and 5 × speed.

FIG. 16 shows the state of the screen when the data recorded in this way is reproduced at a variable speed of 17 times speed. As shown in FIG. 16, when the variable speed reproduction is performed, the screen is divided into 12 areas M1, M2, M3,. Each of the divided areas M1, M2, M3,... Is formed by reproducing the data of the I frame of the HP packet of 160 sync blocks recorded in the overlapping HP area of 90 tracks. Therefore, the area M divided into 12 during variable speed reproduction is
1, M2, M3,... Can all be updated.

FIG. 17 shows that the HP packet data for 160 sync blocks is recorded on 90 tracks so that the same HP packet data is recorded on the track having the same azimuth angle in 36 tracks as described above. The processing is performed.

In FIG. 17, 31 and 32 are input terminals. The input terminal 31 is supplied with data corresponding to the HP packet, and the input terminal 32 is supplied with data corresponding to the SP packet. HP from input terminals 31 and 32
Data corresponding to the packet and SP from input terminal 32
The data corresponding to the packet is supplied to the parallel-serial conversion circuit 33. The data corresponding to the HP packet from the input terminal 31 is supplied to the sync block formatter 34.

The parallel-to-serial conversion circuit 33 converts HP packet data and SP packet data sent in parallel from the input terminals 31 and 32 to serial. The output of the parallel-serial conversion circuit 33 is supplied to the memory 35. The memory 35 stores HP packet data and SP packet data for one track.

A timing signal is supplied from an input terminal 36 to the sync block formatter 34. The output of the sync block formatter 34 is supplied to the memory 37. 160 to be recorded on 90 tracks is stored in the memory 37.
HP packet data for the sync block is stored.

Reference numeral 38 denotes a read address generator. The read address generator 38 is supplied with an area control signal from an input terminal 39. Read address generator 38
Generates a read address based on the area control signal. This read address is supplied to the memory 35. Thereby, the position of the overlapping HP area is set.

Reference numeral 40 denotes a multiplexer. The multiplexer 40 inserts the HP packet data from the memory 37 into the HP packet and SP packet data from the memory 35. The memory 37 includes three memories 37A, 37B, and 37C for 160 sync blocks. Multiplexers 40 include memories 35 and 37
Is supplied. The output of the multiplexer 40 is supplied to the encoder 41.

FIG. 18 shows the read / write timing of the memories 17A to 17C.
Indicates a GOP period. As shown in FIGS. 18B to 18D, first, data is sequentially stored in the memories 37A to 37C. Then, as shown in FIGS. 18D to 18G, data is sequentially read from the memories 37A to 37C in two channels.

FIG. 19 shows a configuration of a reproducing system of the recording / reproducing section 5 of the digital VTR 2. 19, a recording signal of a magnetic tape is reproduced by a rotary head 28 and supplied to a channel decoder 52 via a reproduction amplifier 51. The channel decoder 52 demodulates a reproduction signal by a modulation method corresponding to the channel encoder 26 of the recording system described above.

Reference numeral 53 denotes a TBC (Time Base Corrector). The TBC 53 is for removing the time axis fluctuation component of the reproduction signal. The TBC 53 is provided with a write clock based on a reproduction signal and a read clock based on a reference signal. The output of the channel decoder 52 is supplied to the TBC 53. The TBC 53 removes a time axis fluctuation component in the reproduction signal.

Reference numeral 54 denotes a deframing circuit. The deframing circuit 54 corresponds to the framing circuit 25 of the recording system, and performs an error correction process on the reproduced data. The output of the TBC circuit 53 is supplied to the deframing circuit 54.

Reference numeral 55 denotes a switch circuit. The switch circuit 55 is switched between a case where an AD-HDTV signal is reproduced and a case where a component video signal is reproduced. The output of the TBC circuit 54 is
5 is supplied. When the reproduction signal is an AD-HDTV signal, the switch circuit 55 is switched to the terminal 55A. When the reproduction signal is a component video signal, the switch circuit 55 is switched to the terminal 55B side.

Reference numeral 56 denotes a DCT decompression circuit. The DCT decompression circuit 56 corresponds to the DCT compression circuit 23 of the recording system. That is, the DCT expansion circuit 56 expands the compressed and recorded video signal into the original baseband video signal by decoding the variable length code and performing inverse DCT. The output of the terminal 55B of the switch circuit 55 is supplied to the DCT decompression circuit 56. The compressed video signal is returned to the baseband video signal by the DCT decompression circuit 56, and the video signal is output from the output terminal 57.

Reference numeral 58 denotes a header decoder, and reference numeral 59 denotes a packet selection circuit. The header decoder 58 is an AD-HDTV
And decodes the header of the reproduced signal to determine whether the reproduced signal is I-frame data. Whether the packet is an I-frame packet can be identified from the header of the packet. The header decoder 58 includes a terminal 55A of the switch circuit 55.
Is supplied. The output of the header decoder 58 is supplied to the packet selection circuit 59. During variable speed playback, I
Only frame data is valid. Packet selection circuit 5
9 selects and outputs an I-frame data packet during variable speed reproduction. The output of the packet selection circuit 59 is output from the output terminal 60.

Reference numeral 61 denotes a controller. The controller 61 performs control for switching between normal reproduction and variable-speed reproduction. The controller 61 is supplied with a mode setting signal from the input unit 62. According to this mode setting signal,
The servo circuit 63 and the packet selection circuit 59 are set. At the time of variable-speed reproduction of the AD-HDTV signal, the servo circuit 63 utilizes a tracking signal such as an ATF,
The phase information is added to the tape speed control, the positional relationship between the head trace and the track is always kept the same, and the reproducible area in the track is fixed. As described above, this reproducible area is the overlapping HP area D _HP . Therefore, at the time of variable speed reproduction, data corresponding to the HP packet including the data of the I frame is always reproduced.

[0074]

According to the present invention, when an AD-HDTV signal is recorded in the SD mode of the digital VTR, the transmission rate of the AD-HDTV signal is lower than the source rate in the SD mode. HD packet data including an I frame is redundantly recorded in a marginal area. The area in which the HD packet data is redundantly recorded is allocated to a reproducible area that is fixed when the positional relationship between the head trace and the track is maintained during variable speed reproduction. For this reason, during variable speed playback,
The HP packet including the data of the I frame is reliably reproduced, and the image quality during variable speed reproduction is improved. Further, since the same HP packet data of 32 sync blocks per track is recorded while shifting the location every 90 tracks while overlapping 18 tracks, the entire screen is updated at the time of variable speed reproduction, and the image quality at the time of variable speed reproduction is obtained. Is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a video recording system to which the present invention is applied.

FIG. 2 is a block diagram showing a configuration of a recording system of a digital VTR to which the present invention is applied.

FIG. 3 is a schematic diagram used to explain an overlapping HP area in one embodiment of the present invention.

FIG. 4 is a schematic diagram used to explain an overlapping HP area in one embodiment of the present invention.

FIG. 5 is a waveform diagram showing a relationship between an overlapping HP area and a reproduced RF signal in one embodiment of the present invention.

FIG. 6 is a plan view showing an example of a head arrangement according to an embodiment of the present invention.

FIG. 7 is a plan view showing another example of a head arrangement according to an embodiment of the present invention.

FIG. 8 is a plan view of still another example of a head arrangement according to an embodiment of the present invention.

FIG. 9 is a schematic diagram used for describing one embodiment of the present invention.

FIG. 10 is a schematic diagram used for describing one embodiment of the present invention.

FIG. 11 is a schematic diagram used for describing an embodiment of the present invention.

FIG. 12 is a schematic diagram used for describing one embodiment of the present invention.

FIG. 13 is a schematic diagram used for describing an embodiment of the present invention.

FIG. 14 is a schematic diagram used for describing one embodiment of the present invention.

FIG. 15 is a schematic diagram used for describing one embodiment of the present invention.

FIG. 16 is a schematic diagram used for describing one embodiment of the present invention.

FIG. 17 is a block diagram illustrating a specific configuration of a format conversion unit according to an embodiment of the present invention.

FIG. 18 is a timing chart used for describing a format conversion unit in the embodiment of the present invention.

FIG. 19 is a block diagram showing a configuration of a recording system of the digital VTR.

FIG. 20 is a block diagram illustrating an example of a configuration of a transmission system of the AD-HDTV system.

FIG. 21 is a schematic diagram used for describing a GOP configuration in the AD-HDTV system.

FIG. 22 is a schematic diagram illustrating a configuration of a transmission packet in the AD-HDTV system.

FIG. 23 is a schematic diagram illustrating a configuration of a transmission packet in the AD-HDTV system.

FIG. 24 is a schematic diagram illustrating a configuration of a transmission packet in the AD-HDTV system.

[Explanation of symbols]

 3 Digital VTR 4 Interface and format converter 5 Recording / reproducing unit 35, 37 Memory 38 Read address generator 40 Multiplexer

Claims (12)

(57) [Claims] 1. DCT (Discrete Cosine Transform)
The packet data with high importance of the high efficiency coding method signal is stored in a marginal recording area caused by the transmission rate of the high efficiency coding method signal that combines A digital video signal recording method for recording in an overlapping manner, wherein a plurality of overlapping areas are provided for each track ,
Of the 2n (n is the double speed during variable speed playback) track
1 in the multiple overlapping areas of the track having an azimuth angle of
Duplicate recording of two important packet data
Second azimuth angle of approximately 2n consecutive tracks
Another important point in the above overlapping areas of the track
A digital video signal recording method in which high-degree packet data is recorded in duplicate . 2. The multiple speed number n at the time of the variable speed reproduction is (n = 1
7) , and the number of tracks of the approximately 2n tracks is 36
2. The video signal recording method according to claim 1, wherein the video signal is a track. 3. DCT (Discrete Cosine Transform)
Of High Efficiency Coding System Combining Motion and Motion Compensation
The transmission rate of the digital video signal is
Above the height,
Packet data of high importance for the efficiency coding signal
This is a digital video signal recording method for recording multiple
Of continuous 2n tracks (n is a double speed during variable speed reproduction)
One of the tracks with the first azimuth angle
Duplicate recording of highly important packet data
The second azimuth angle of approximately 2n tracks that follow
One more important packet data on multiple tracks
Digital video signal with duplicate data recorded
Number recording method. 4. The multiple speed number n during the variable speed reproduction is (n = 1
7), and the number of tracks of the approximately 2n tracks is 36
4. A video signal recording method according to claim 3, wherein the video signal is a track. 5. DCT (Discrete Cosine Transform)
Transmission of high-efficiency coding scheme signal was Align set compensation and motion
The transmission rate of the digital video signal is
Above the height,
Packet data of high importance for the efficiency coding signal
This is a digital video signal recording method for recording multiple
Te, that you want to correspond to the data of 1GOP (Group Of Picture) period
The number of racks is M, and the duplication related to the number of double speeds during variable speed playback
Assuming that the number of tracks is N, the number N of overlapping tracks is added to the data of the 1 GOP cycle.
The number of tracks M is a divisor, and the number of tracks M corresponding to the data of one GOP cycle is
And the first track of a continuous (2 × N) track
One track with high importance is placed on N tracks that
The packet data is recorded in duplicate and the above continuous (2 ×
N) N tracks having a second azimuth angle among the tracks
Another important packet data of high importance
Digital video signal recording method for multiple recording
Law. 6. A data corresponding to the data of one GOP cycle.
Assuming that the number of racks M is (M = 90),
The number N of overlapping tracks related to the number is (N = 18),
(N-1 = 17)
6. The digital video signal recording method according to claim 5. 7. DCT (Discrete Cosine Transform)
Directly encodes high-efficiency coding signals that combine
Digital video signal recorded on magnetic tape
In the recording device, A plurality of overlapping areas are provided per track,
Of the 2n (n is the double speed during variable speed playback) track
1 in the multiple overlapping areas of the track having an azimuth angle of
Duplicate recording of two important packet data
Second azimuth angle of approximately 2n consecutive tracks
Another important point in the above overlapping areas of the track
Provision of means to record high-degree packet data redundantly
To Digital video signal recording apparatus. 8. The multiple speed number n at the time of variable speed reproduction is (n = 1
7), and the number of tracks of the approximately 2n tracks is 36
8. A video signal recording device according to claim 7, which is a track. Recording device. 9. DCT (Discrete Cosine Transform)
Directly encodes high-efficiency coding signals that combine
Digital video signal recorded on magnetic tape
In the recording device, Of approximately 2n (n is a double speed during variable speed reproduction)
One of the tracks with the first azimuth angle
Duplicate recording of highly important packet data
The second azimuth angle of approximately 2n tracks that follow
One more important packet data on multiple tracks
Provision of means for duplicating recording of data Digit
Video signal recording device. 10. The multiple speed number n at the time of the variable speed reproduction is (n = 1
7), and the number of tracks of the approximately 2n tracks is 36
10. The video signal recording device according to claim 9, which is a track. 11. DCT (Discrete Cosine Transform)
 ) And motion compensation
Digital video signal recorded on magnetic tape
In the number recording device, Toe equivalent to data of one GOP (Group Of Picture) cycle
The number of racks is M, and the duplication related to the number of double speeds during variable speed playback
If the number of tracks is N, The number of overlapping tracks N is added to the data of one GOP cycle.
It is a divisor of the number of applicable tracks M, The number of tracks M corresponding to the data of one GOP cycle is
And the first track of a continuous (2 × N) track
One track with high importance is placed on N tracks that
The packet data is recorded in duplicate and the above continuous (2 ×
N) N tracks having a second azimuth angle among the tracks
Another packet with the same importance as another packet data.
Means of duplicating recording Digital video
E signal recording device. 12. Corresponding to the data of one GOP cycle.
The number of tracks M is assumed to be (M = 90), which is twice that of the above-mentioned variable speed reproduction.
The number N of overlapping tracks related to the speed is (N = 18),
(N-1 = 17)
The digital video signal recording device according to claim 5.