JP3480517B2 - Digital VTR - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video tape recorder (hereinafter referred to as a digital VTR) having a track format for recording a digital video signal and a digital audio signal in each of predetermined areas of an oblique track. , A digital video signal and a digital audio signal are input as a bit stream, and the present invention relates to a digital VTR for recording the bit stream.

[0002]

2. Description of the Related Art FIG. 6 is a general household digital VTR.
It is a figure which shows the track figure of. In the figure, the magnetic tape 100 has diagonal tracks, and one track is a video area 1 for recording a digital video signal.
01 and an audio area 102 for recording a digital audio signal.

Now, such a home digital VTR
There are two ways to record video and audio signals on the. One is a so-called baseband recording method in which an analog video signal and an audio signal are input and recording is performed using a high-efficiency encoder for video and audio. The other is a so-called transparent recording system for recording a digitally transmitted bit stream.

ATV being discussed in the United States
The latter transparent recording method is suitable for recording the (Advanced Television) signal. The reason is that the ATV signal is already a digitally compressed signal and a high-efficiency encoder or decoder is not necessary, and since it is recorded as it is, there is no deterioration in image quality. On the other hand, the disadvantage is the image quality during high-speed reproduction, special reproduction such as still and slow reproduction. Particularly, if the bit stream is recorded on the diagonal track as it is, almost no image can be reproduced at the time of high speed reproduction.

As a digital VTR system for recording such an ATV signal, "Inte" held in Ottawa, Canada from October 26 to 28, 1993.
national workshop on HDT
"A Recordi" was added to the technical announcement at V'93.
ng Method of ATV data ona
"Consumer Digital VCR". Hereinafter, the contents will be described as a conventional example.

As a basic specification of a home digital VTR prototype, SD (Standard Define) is used.
mode), the recording frequency of the digital video signal is 25 Mbps and the field frequency is 60H.
In the case of z, there is one that records one frame of video in the video area of 10 tracks. Here, if the data rate of the ATV signal is set to 17 to 18 Mbps, transparent recording of the ATV signal becomes possible in this SD mode.

FIG. 7 shows the normal reproduction of the digital VTR,
It is a figure which shows the head trace at the time of high speed reproduction. In the figure, each track is alternately recorded obliquely by heads having different azimuth angles. During normal reproduction, the tape feed speed is the same as during recording, so the head can trace along the recording track as shown in FIG. 7 (A). However, during high speed reproduction, the tape speeds are different, so that it is possible to trace across several tracks and reproduce only the fragments of each same azimuth track.
FIG. 7B shows the case of fast-forwarding at 5 times speed.

In the MPEG2 bit stream, only intra-coded blocks can be independently decoded without referring to other frames. If the MPEG2 bit stream is recorded on each track in order,
In the reproduction data at the time of high speed reproduction, an image is reconstructed from the burst using only the intra code. At this time, the reproduced area is not continuous on the screen, and the block fragments spread on the screen. Furthermore, since the bitstream is variable length coded,
There is no guarantee that all of the screens will be updated periodically,
Some parts may not be updated for a long time. As a result, the image quality during high speed playback is not sufficient and may not be acceptable in home digital VTRs.

FIG. 8 is a block diagram of a conventional bit stream recording apparatus capable of high speed reproduction. Here, the video area of each track is divided into a main area for recording a bit stream of all ATV signals and a copy area for recording an important part (HP data) of the bit stream used for image reconstruction at high speed reproduction. Divide. During high-speed playback, only the intra-coded block is effective, so this is recorded in the copy area. However, in order to further reduce the data, the low-frequency components are extracted from all intra-coded blocks and the HP data To record as. Figure 8
1, 1 is a bitstream input terminal, 2 is a main area bitstream output terminal, 3 is HP data output terminal, 200 is a variable length decoder A, 201 is a counter A, 202 is a data sampling circuit A, 203 is E
This is an OB (End of Block) addition circuit A.

The MPEG2 bit stream is input from the input terminal 1 and output from the output terminal 2 as it is,
It is sequentially recorded in the main area. On the other hand, the bit stream from the input terminal 1 is also input to the variable length decoder A200, the syntax of the MPEG2 bit stream is analyzed, the intra image is detected, the timing is generated by the counter A201, and the data sampling circuit A202 is detected. The low frequency components of all the blocks of the intra image are extracted by, and the EOB code is added by the EOB adding circuit A203 to form HP data, which is recorded in the copy area.

FIG. 9 shows a conceptual diagram during reproduction. During normal reproduction, all bitstreams recorded in the main area 300 are reproduced, and M bits outside the digital VTR are reproduced.
It is sent to the PEG2 decoder. The HP data recorded in the copy area 301 is discarded. This selection is made in the data separation 302. On the other hand, during high speed playback, copy area 3
Only 01 HP data is collected and sent to the decoder,
The main area bitstream is discarded. This selection is also made in the data separation 302.

Next, FIG. 10 shows an example of a head trace during high speed reproduction. If the tape speed is an integral multiple speed and phase lock control is performed, head scanning is synchronized with the same azimuth track. Therefore, the position of the reproduced data is fixed. In FIG. 10, assuming that a portion where the output level of the reproduction signal is higher than −6 dB is reproduced, a shaded area is reproduced by one head. FIG. 10 shows an example of 9 × speed, and at 9 × speed, signal reading of this shaded area is guaranteed. Therefore, HP data may be recorded in this area. However, at other speeds, signal reading is not guaranteed and this area must be chosen for reading at some tape speeds.

[0013] Figure 11 is Ri FIG der showing an example of three scan region of the tape speed, the head is an example of three scan region of the tape speed to be synchronized to the same azimuth tracks. The area scanned at each tape speed has some overlapping areas. A copy area is selected from these areas to ensure the reading of HP data at different tape speeds. Although FIG. 11 shows the case of fast-forwarding of 4 times, 9 times, and 17 times, these scan areas are -2 times,
This is the same as in the case of fast-forwarding -7 times and -15 times.

At some tape speeds it is not possible for the head to trace the exact same area. This is because the number of tracks traversed by the head differs depending on the tape speed. In addition, it should be possible to trace from any one of the same azimuth tracks. FIG. 12 shows examples of head traces at different tape speeds. In FIG. 12, areas 1, 2, and 3 are selected from the overlapping area of 5 × speed and 9 × speed. By repeatedly recording the same HP data on 9 tracks, the HP data can be read at either 5 × speed or 9 × speed.

FIG. 13 is a diagram showing an example of a head trace at 5 × speed. As can be seen from FIG. 13, by repeatedly recording the same HP data on the same number of tracks as the tape speed, the HP data can be read by the head synchronized with the same azimuth track. Therefore, by repeating the HP data copy to the same number of tracks as the tape speed when performing the maximum high-speed reproduction within the specified double speed, the HP data can be read in the forward and backward directions at several tape speeds. To do.

FIG. 14 is a diagram showing an example of a main area and a copy area. In the home digital VTR, the video area of each track is composed of 135 sync blocks, the main area is 97 sync blocks, and the copy area is 32 sync blocks. For this copy area, the overlapping areas corresponding to 4, 9, and 17 times speed shown in FIG. 11 are selected. In this case, the data rate in the main area is about 17.46 Mbps, and the same data is recorded 17 times in the copy area, which is about 338.8 kbps.

[0017]

Since the conventional apparatus is constructed as described above, the EOB code is always added to the data recorded in the copy area 301.
If one B code is 4 bits, the number of blocks in a 4 × 1 screen is 46080 (1920HX1024V, 4:
Luminance color difference component signal of 2: 0) = 184320
Bits are always needed.

The EOB code is a code indicating the end of the data of the DCT block and does not contribute to the image quality at all. There is a problem that the copy area 301 of 184320 bits is used for this EOB code.

The present invention has been made to solve the above problems, and is a system for recording a predetermined number of DCT coefficients in a copy area or a predetermined number of variable length codes in a copy area. It is an object of the present invention to provide a digital VTR capable of effectively using the copy area in the system, and capable of preventing a contradiction between the header information and the reproduced bit stream during reproduction.

[0020]

A digital VTR according to claim 1 of the present invention is at least a digital video signal.
Is entered in a bitstream and this bitstream
V for recording data by the transparent recording method
In TR, remove header information from bitstream
First extracting means to be taken and correction to the header information
And the intra-coding block from the bitstream.
And a means for detecting the component and extracting the component.
Data for high-speed playback of intra-coded block components
The number of orthogonal transform coefficients used as
And a mode designating means for designating according to
Consists of a predetermined number of orthogonal transform coefficients specified by the stage
Only the minute is the extracted intra-coded block component
A second extracting means for removing the second
A predetermined number of orthogonal transformation coefficients extracted by the scraping means
Is composed of EOB (End Of Block)
And the modified header information
Both of the input bits are used as high-speed playback data.
Recording in an area different from the area where the stream is recorded
It is characterized by doing.

In the digital VTR according to the second aspect of the present invention, at least the digital video signal is a bit stream.
Input in stream and the bitstream is variable length code
And transpose the bitstream
In a digital VTR that records by the rent recording method,
First pruning of header information from bitstream
And a means for correcting the header information and a bit
The intra-coded block from the stream
Means for extracting components and said extracted intra-coding
Can be used as data for high-speed playback among block components
Specify the predetermined number of variable length codes according to the double speed number of high speed playback.
Mode specifying means and the mode specifying means
Only the components consisting of a predetermined number of variable length codes are extracted.
Second extraction for extracting from the encoded intra-coded block component
And removing means by the second extracting means.
EOB the component consisting of a predetermined number of variable length codes
Do not add (End Of Block) code
In addition, the data for high-speed playback together with the modified header information
The input bit stream is recorded as a data
It is characterized by recording in an area different from the area
It

In the digital VTR according to a third aspect of the present invention, the mode designating means sets the orthogonal transform coefficient of the orthogonal transform coefficient.
Of these, only the DC value (DC component) is the data for high-speed reproduction.
It can be specified to be used as
Extraction means, according to the designation of the mode designation means,
From the extracted intra-coded block components, the
Extract only the DC value (DC component) from the conversion coefficient
And the second extracting means
The extracted direct current value (DC component) is
Recorded as high-speed playback data with header information
It is characterized by

A digital VTR according to a fourth aspect of the present invention reproduces a bit stream recorded by the digital VTR according to any one of the first to third aspects .
The playback mode control hand that specifies the double speed of playback.
And the high-speed reproduction data of the reproduction signal is recorded.
Playback bit stream from the area
Specified by the means for separating and the playback mode control means
The number of orthogonal transform coefficients that corresponds to the
Is an EOB (End Of Block) code for the variable length code
Means for adding and reproducing.

In the digital VTR according to claim 5 of the present invention, at least a digital video signal is input as a bit stream, and the bit stream is formed by variable length coding using a plurality of code maps. In a digital VTR for recording in a transparent recording system, there is provided means for extracting header information from a bitstream, means for correcting the header information, means for detecting an intra-coded block from the bitstream, and means for extracting the component, When one track is composed of the main area 300 for recording the input bit stream and the copy area 301 for recording HP data for high-speed reproduction, a predetermined number of orthogonal transformations are performed on the components of the extracted intra-coded block. As a component consisting of a coefficient and add to that component That the EOB code to the shortest EOB code from the plurality of code maps, the EO to said component
A B code is added to form HP data for high speed reproduction.

In the digital VTR according to claim 6 of the present invention, at least a digital video signal is input as a bit stream, and the bit stream is formed by variable length coding using a plurality of code maps. In a digital VTR for recording in a transparent recording system, there is provided means for extracting header information from a bitstream, means for correcting the header information, means for detecting an intra-coded block from the bitstream, and means for extracting the component, When one track is composed of the main area 300 for recording the input bit stream and the copy area 301 for recording HP data for high-speed reproduction, the components of the extracted intra-coded block are converted into DC of orthogonal transform coefficients. Add only to the component and add to the DC component The EOB code is the shortest EOB code from the plurality of code maps, the E to the DC component
An OB code is added to form HP data for high speed reproduction.

In the digital VTR according to claim 7 of the present invention, at least a digital video signal is input as a bit stream, and the bit stream is configured by variable length coding using a plurality of code maps. In a digital VTR for recording in a transparent recording system, there is provided means for extracting header information from a bitstream, means for correcting the header information, means for detecting an intra-coded block from the bitstream, and means for extracting the component, When one track is composed of the main area 300 for recording the input bit stream and the copy area 301 for recording HP data for high speed reproduction, the components of the extracted intra-coded block are set to a predetermined number of variable lengths. A component consisting of a code and added to the component The EOB code is the shortest EOB code from the plurality of code maps, the EO to said component
A B code is added to form HP data for high speed reproduction.

Further, in the digital VTR according to claim 8 of the present invention, at least the signal in the header for identifying the code map used by the bit stream input from the plurality of code maps is transmitted to the plurality of code maps. To modify the signal to show the code map with the shortest EOB code.

[0028]

In the digital VTR according to the first aspect of the present invention, the bit stream of the digital video signal can be efficiently recorded in the copy area 301 for recording the high speed reproduction data.

Further, in the digital VTR according to the second aspect of the present invention, the bit stream of the digital video signal is efficiently recorded in the copy area 301 for recording the high speed reproduction data, and the refresh at the high speed reproduction is accelerated. You can

Further, in the digital VTR according to the third aspect of the present invention, the bit stream of the digital video signal can be efficiently recorded in the copy area 301 for recording the high speed reproduction data.

Further, in the digital VTR according to claim 4 of the present invention, it is possible to reproduce the bit stream recorded as in the digital VTR according to any one of claims 1 to 3 of the present invention. .

In the digital VTR according to the fifth aspect of the present invention, the bit stream of the digital video signal including the EOB code can be efficiently recorded in the copy area 301 for recording the high speed reproduction data.

Further, in the digital VTR according to the sixth aspect of the present invention, the bit stream of the digital video signal including the EOB code can be efficiently recorded in the copy area 301 for recording the high speed reproduction data.
You can speed up refreshing during high-speed playback.

Further, in the digital VTR according to the seventh aspect of the present invention, the bit stream of the digital video signal including the EOB code can be efficiently recorded in the copy area 301 for recording the high speed reproduction data.

Further, in the digital VTR according to the eighth aspect of the present invention, the length of the EOB code can be made the shortest in the code map used in the variable length coding.

[0036]

【Example】

Example 1. An example of the embodiment of the present invention is shown in FIG. In FIG. 1, 1 is a bitstream input terminal, 2 is a main bitstream output terminal, 3 is an output terminal for HP data that is high-speed playback data, 5 is a header extraction circuit, 7 is a header modification circuit, and 9 is a modified header output. A terminal, 11 is a variable length decoder B, 13 is a counter B, 15 is a data sampling circuit B, 17 is a special reproduction mode control circuit A for controlling a signal path according to a high-speed reproduction mode, 19 is a switch A, 2
Reference numeral 1 is an EOB addition circuit B, 23 is a signal path A to which EOB is not added, and 25 is a switch B.

Next, the operation of FIG. 1 will be described. AT
The V bit stream is input from the bit stream input terminal 1. While output from the main bit stream output terminal 2 as the main bit stream for normal reproduction is inputted to the header extraction circuit 5. The header extraction circuit 5 extracts the header part from the input ATV bit stream and outputs it to the header correction circuit 7.
The remaining data is output to the variable length decoder B11. The ATV bit stream is also input to the data extracting circuit B15.

The header correction circuit 7 applies a predetermined correction to the header extracted by the header extraction circuit 5 and outputs it from the modified header output terminal 9. At this time, various modifications can be considered, but one example is Example 2
Shown in. The corrected header information is recorded in the copy area 301 together with HP data for high speed reproduction.

The variable length decoder B11 sequentially performs variable length decoding of the input bit stream. At this time, the counter B13 counts the number of variable-length decoded DCT coefficients. The counter B13 outputs a timing signal for extracting data to the data extracting circuit B15 when the number of DCT coefficients reaches a predetermined value based on a signal from a trick-play mode control circuit A17 described later. The data extracting circuit B15 outputs a counter B from the input bit stream.
Data is extracted from 13 at the designated timing.

Next, the special reproduction mode control circuit A17 is based on the number of predetermined DCT coefficients determined corresponding to the double speed number of the high speed reproduction, or the number of DCT coefficients specified by the user from the outside when the recording is executed. Switch A19,
And the switch B25. Also for the counter 13 described above, D to be extracted from the bit stream
A signal for informing the number of CT coefficients is output.

In this embodiment, it is considered that only the DC component (DC value) is extracted from the DCT coefficient, and that the DC component is included and the AC component (AC value) is also included.
First, in the case of extracting only the DC component, the DC component is always included in the DCT block (8 lines × 8 pixels on the screen), which is the minimum coding unit in the bitstream,
In this case, it is not necessary to add the EOB code. This is because the EOB code is a signal indicating that there is no significant data in the 1DCT block which is the minimum coding unit and the transmission of the data of the block is terminated here. If the end is known in advance, it is added. Because there is no need. When recording, make sure that the data of 1DCT block is only DC, or if the system on the playback side is 1D
If the number of DCT coefficients recorded per CT block is known, it is not necessary to add the EOB code. For example, if a system for recording HP data in which the DCT coefficient is composed of only DC is configured, it is not necessary to add an EOB code on the recording side, and the copy area 301 can be effectively used.

The above will be described again with reference to FIG. If a plurality of significant AC components are included as shown in FIG. 2A (α, β, and γ in FIG. 2A), 64 pieces of data are transmitted, or an insignificant coefficient is used. However, a code indicating that it does not exist beyond this, that is, an EOB code must be added. The transmission of 64 pieces of data is not actually performed because it has no meaning in performing compression encoding. However, in the case of FIG. 2B, when only the DC component exists and there is no significant AC component, if it is known from the beginning that there is only such a block, when the DC component can be recognized, the DC component is not present. Since there are only unintentional coefficients and the end of the DCT block can be known, it is meaningless to add the EOB code during recording.

That is, if it is known that there is only a block as shown in FIG. 2B at the time of reproduction, the end of the 1DCT block can be recognized without fail, and if the decoder always outputs E.
If an OB code is required, it can be added during playback. Therefore, the EOB code can be removed during recording.

As described above, since it is not necessary to add the EOB code when extracting only the DC component, the switch A19 and the switch B25 of FIG. 1 are connected to the lower side, and the bit stream extracted by the data extracting circuit B15. Is output to the HP data output terminal for high speed reproduction through the signal path A23.

When the DC component and the AC component are included, it is necessary to add the EOB code.
Switch A19 and switch B25 are connected to the upper side, and E
The EOB code is added by the OB adding circuit B21 and is output from the HP data output terminal 27 for high speed reproduction.

With this configuration, redundant EOB code can be deleted for one DCT block, and data of many DCT blocks can be recorded in the same copy area 301 as the conventional example.

In this embodiment, the case where only the DC component is recorded has been described, but the number of coefficients transmitted in one DCT block may be any number as long as it is predetermined.

In this embodiment, the coefficient of one DCT block is counted so as to be a predetermined number, but the variable length code (V
You may count so that the number of LC codes) may become a predetermined number.

Example 2. In the second embodiment, an example in which the header is modified in the first embodiment and a method for shortening the EOB code even when the EOB code is added to the DC component will be described. This allows HP data to be read out in a predetermined format, for example, and can be transmitted to the decoder as it is without the need to perform processing such as insertion of a new signal.

In ATV, MP is used as the video compression method.
I am using EG-2. In MPEG-2, variable length coding is used as a coding method for DCT coefficients. There are two types of code maps for this variable length coding, and which one is used is determined by a flag in the header. FIG. 3 shows a part of the above two types of code maps for variable length coding.

In MPEG-2, a part of the header called the picture coding extension has a flag for determining which of the variable length coding code maps shown in FIG. 3 is to be used. Looking at this flag, the MPEG-2 decoder determines which of the variable length coding code maps shown in FIG. 3 is to be used.

In the present embodiment, the data extracted from the main bitstream is only the DC component, and EOB
The case of adding a code will be described.

FIG. 4 is a diagram showing another embodiment of the present invention. In the figure, 1 to 15 are the same as those in the first embodiment and will therefore be omitted. 34 is a special mode control circuit B, 35 is EO
B is the additional circuit C.

Next, the operation will be described. EOB
The addition circuit C35 adds an EOB code of "10" as an EOB code to the data extracted by the data extraction circuit B15. This is because the data sampled in the data sampling circuit B15C is D as described above.
This is the case of only the DC component of the CT coefficient, which is instructed by the trick-play mode control circuit B34. The data to which the EOB code is added is output from the HP data output terminal 3 for high speed reproduction.

In this case, however, (A) is used in the code map for variable length coding shown in FIG. 3, and it is necessary to indicate that to the flag of the header. This is because the original bit stream may use the code map of FIG. 3B, and if the header is used as it is, the data and the map may not match.

Therefore, regardless of the state in which the above-mentioned flag is input from the header extracted by the header extraction circuit 5 as a part of a predetermined portion, the code map of FIG. 3A is modified to be used. . In MPEG-2, if this flag is 0, the code map of FIG. 3A is used. Therefore, in high-speed reproduction (when only the DC component is used), this flag is always set to 0 and 2 bits of "10" are set. EOB code is added.

By doing so, since the length of the EOB code to be added is only 2 bits, the total code amount can be limited, and more D areas can be stored in the predetermined copy area 301.
CT block data can be recorded. Further, since the EOB code is always added, data can be transmitted to the decoder without inserting a new signal.

In the present embodiment, the case where only the DC component is handled has been described, but the number of coefficients to be transmitted among the coefficients of one DCT block may be any number.

In this embodiment, the coefficient of one DCT block is counted so as to be a predetermined number, but the variable length code (V
You may count so that the number of LC codes) may become a predetermined number.

Example 3. In this embodiment, reproduction of HP data recorded as in the first embodiment will be described.

FIG. 5 is a block diagram showing the reproducing system of the present invention. In the figure, 300 is a main area in which normal reproduction data is recorded, 301 is a copy area in which HP data for high-speed reproduction is recorded, 400 is a data separation B for separating reproduction data, 401 is a switch C, and 402 is a The EOB adding circuit D, 403 is a signal path B for transmitting data that does not need to be added with an EOB code, and 404 is a switch D.

Next, the operation will be described. During normal reproduction, the signals reproduced from the main area 300 and the copy area 301 are input to the data separation B400, where the data in the copy area 301 is discarded and the main area 30
Data of 0 is data separation B400 as normal reproduction data
Is output from.

Next, at the time of high speed reproduction, the data separation 40
It is the same as above until it is input to 0. In the trick-play mode control circuit B34, for example, a double speed H specified by the user is used.
A signal for controlling the P data to be output from the data separation B400 is output. As shown in the first embodiment, the case of reproducing only the DC component of the DCT coefficient and the case of adding A in addition to the DC component
When the C component is also reproduced, the switch C40 located in the latter stage
The special reproduction mode control circuit B34 also outputs a signal for controlling 1 and the switch D404.

During high speed reproduction, the data separation B400 outputs the data of the double speed number designated by the special reproduction mode control circuit B34 of the data in the copy area 301. At this time, as described in the first embodiment, there are cases where only the DC component of the DCT coefficient is reproduced and cases where the AC component is also reproduced in addition to the DC component. First, the case of reproducing HP data for high speed reproduction of only the DC component will be described. Special mode control circuit B34
Instructs the data separation B400, the switch C401, and the switch D404 to reproduce the HP data of only the DC component.

The switch C401 is connected to the upper side according to an instruction from the trick-play mode control circuit B34, the EOB code is added by the EOB adding circuit D402, and the switch D404 is similarly connected to the upper side according to the instruction from the trick-play mode control circuit B34. And is output as HP data for high speed reproduction.

When reproducing the HP data including the AC component in addition to the DC component, the switches C401 and D4 are used.
04 is connected to the lower side. The HP data output from the data separation B400 passes through the switch C401, the signal path B403 not added with the EOB code, and the switch D4.
It is output as HP data for high speed reproduction through 04.

In this way, the data in the main area 300 and the data in the copy area 301 recorded as in the first embodiment can be reproduced.

In the third embodiment, the reproduction of the data recorded as in the first embodiment has been described, but the data recorded in the second embodiment can be reproduced in the same manner as in the conventional example.

[0069]

As described above, according to the digital VTR described in claim 1 of the present invention, the EOB code can be deleted and a large number of DCT blocks can be recorded in the limited recording area.

According to the digital VTR according to the second aspect of the present invention, the EOB code can be deleted,
More DCT blocks can be recorded in the limited recording area, and the refresh at the time of reproduction can be speeded up.

Further, according to the digital VTR of the third aspect of the present invention, the EOB code can be deleted,
Many DCT blocks can be recorded in the limited recording area.

Further, according to the digital VTR described in claim 4 of the present invention, it is possible to reproduce the recorded bit stream like the digital VTR described in any one of claims 1 to 3 of the present invention. .

Further, according to the digital VTR of the fifth aspect of the present invention, even when recording an EOB code, it is possible to record many DCT blocks in a limited recording area by shortening the EOB code. it can.

According to the digital VTR of the sixth aspect of the present invention, even when recording an EOB code, it is possible to record many DCT blocks in a limited recording area by shortening the EOB code. Yes, you can speed up the screen refresh during playback.

Further, according to the digital VTR described in claim 7 of the present invention, even when an EOB code is recorded, it is possible to record many DCT blocks in a limited recording area by shortening the EOB code. it can.

According to the digital VTR described in claim 8 of the present invention, the code map used by the bit stream in the digital VTR described in any of claims 5 to 7 of the present invention is reproduced. It can be identified without conflict.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a 1DCT block.

FIG. 3 is a code map for variable length coding used in a coding method used by the method / apparatus of the present invention.

FIG. 4 is a diagram showing another embodiment of the present invention.

FIG. 5 is a diagram showing a reproduction system of the present invention.

FIG. 6 is a diagram showing a track of a general home digital VTR.

FIG. 7 is a diagram showing head traces during normal reproduction and high-speed reproduction of a digital VTR.

FIG. 8 is a block diagram of a conventional bitstream recording device capable of high-speed reproduction.

FIG. 9 is a diagram showing a conventional concept during reproduction.

FIG. 10 is a diagram showing an example of a head trace during high speed reproduction.

FIG. 11 is a diagram showing an example of scan areas of three tape speeds.

FIG. 12 is a diagram showing examples of head traces at different tape speeds.

FIG. 13 is a diagram showing an example of a head trace at 5 × speed.

FIG. 14 is a diagram showing an example of a main area and a copy area.

[Explanation of symbols]

5 Header extraction circuit, 7 Header correction circuit, 17
Special mode control circuit A, 19 switch A, 23 EO
Signal path A without B code, 25 switch B.

Continuation of front page (56) Reference JP-A-7-250303 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04N 5/76-5/956 G11B 20/10-20 / 12

Claims (8)

(57) [Claims] 1. In a digital VTR in which at least a digital video signal is input as a bit stream and the bit stream is recorded by a transparent recording method, a first extracting means for extracting header information from the bit stream, and modifying the header information. fast means and detects the intra-coded blocks from a bit stream, means for extracting the components, among the extracted intra-coded block component added
Set the number of orthogonal transform coefficients used as
A mode designating means for designating in accordance with the number of times of fast reproduction, and a predetermined number of orthogonal transforms designated by the mode designating means.
Only the component consisting of the conversion coefficient is the extracted intra code
Second extraction means for extracting from the block component
The predetermined number of pieces extracted by the second extracting means.
The component consisting of the orthogonal transform coefficient is converted into EOB (End Of B
lock) without adding the code
As the data for high speed playback together with the header information,
Different from the area that records the input bitstream
Digital VTR characterized by recording in area . 2. A digital VTR in which at least a digital video signal is input as a bit stream, the bit stream is constituted by a variable length code, and the bit stream is recorded by a transparent recording method. First header information is extracted from the bit stream. For extracting the intra-coded block from the bitstream, and means for correcting the header information
And, means for extracting the components, high-speed of the extracted intra-coded block component
A predetermined number of variable-length codes used as data for reproduction is
A mode designating means for designating in accordance with the number of times of speed reproduction, and a predetermined number of variable length characters designated by the mode designating means.
Of the extracted intra-coded block only
Second extracting means for extracting from the lock component, and a predetermined number of extractable parts extracted by the second extracting means.
EOB (End Of Bloc)
k) the modified header without adding code
It is input as data for high-speed playback together with information.
Area different from the area where the bitstream is recorded
A digital VTR characterized by being recorded on . 3. The mode designating means is the orthogonal transform section.
Only the DC value (DC component) of the number
It is possible to specify that it is used as a data, and the second extracting means specifies the mode specifying means.
According to the extracted intra-coded block component
To the DC value (DC component) of the orthogonal transformation coefficient
Only the DC value (DC component) extracted by the second extracting means can be extracted.
Minutes) for high speed playback with the modified header information
The digital VTR according to claim 1, which is recorded as data of 4. The high-speed reproduction data among reproduction signals
Components of the playback bitstream from the recorded area
Is composed of a predetermined number of orthogonal transform coefficients or variable length codes.
And a reproduction mode control means for designating a double speed of reproduction and an area in which the high speed reproduction data of the reproduction signal is recorded.
Playback bitstream from A as high-speed playback signal
The means for separating and the playback speed specified by the playback mode control means
The number of orthogonal transform coefficients or variable length code
(End Of Block) Code addition means to play
Digital VTR according to any to claims 1 to 3, characterized in that it has and. 5. A digital VTR in which at least a digital video signal is input as a bit stream, the bit stream is configured by variable length coding using a plurality of code maps, and the bit stream is recorded by a transparent recording method. An area for recording the input bit stream and a high-speed reproduction are provided, which have means for extracting header information from the stream, means for correcting the header information, means for detecting an intra-coded block from the bit stream, and means for extracting the component. EOB (End Of Block) to be added to the component of the extracted intra-coded block as a component consisting of a predetermined number of orthogonal transform coefficients when forming one track in the area for recording the HP data for use Select the code from the code maps above. Short and EOB codes, digital VTR, characterized in that it comprises means for configuration by adding the EOB code to the components as HP data for high speed reproduction. 6. A digital VTR in which at least a digital video signal is input as a bit stream, the bit stream is configured by variable length coding using a plurality of code maps, and the bit stream is recorded by a transparent recording method. An area for recording the input bit stream and a high-speed reproduction are provided, which have means for extracting header information from the stream, means for correcting the header information, means for detecting an intra-coded block from the bit stream, and means for extracting the component. EOB (End Of Block) to be added to the component of the extracted intra-coded block as a component consisting of a predetermined number of variable-length codes when one track is configured in an area for recording HP data for Most of the code from the code maps above There was a EOB code, the digital VTR, characterized in that it comprises means for configuration by adding the EOB code to the components as HP data for high speed reproduction. 7. The digital VT according to claim 5, wherein the component of the extracted intra-coded block is only a direct current value (DC component) among the orthogonal transform coefficients.
R. 8. The means for modifying the header information is at least the shortest signal from the plurality of code maps in the header that identifies the code map used by the bitstream input from the plurality of code maps. EO
8. A digital VTR according to claim 5, wherein the signal is modified so as to show a code map having a B code.