JPH08205081A - Digital data recording method - Google Patents

Abstract

PURPOSE: To attain the recording suitable for special reproduction in the case of recording of different bit rate data and the transmission of plural program data by attaining excellent special reproduction in a digital VTR regardless of head arrangement, tape reproduction speed and tape feed phase so as to set effectively a special reproduction data area. CONSTITUTION: The video data area of a recording track is divided into 135 SYNC blocks and a special reproduction data area TPA and a usual reproduction data area NPA are allocated to each SYNC block. The special reproduction data area TPA changes depending on the amount of usual reproduction data to be obtained and the special reproduction data area is decided accordingly and the data are recorded therein. The data are recorded at a tape speed corresponding to the data amount to be obtained, then the number of times of repetition is set for each block (m-sets of tracks) of special reproduction data in response to a tape speed. Plural program data are selected from the data and the program data are alternately recorded in the unit of blocks.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital VTR for recording / reproducing video signals and audio signals as digital data.
The present invention relates to a digital data recording method used for a (video tape recorder), and particularly to a digital data recording method capable of favorably performing special reproduction.

[0002]

2. Description of the Related Art A, the next-generation digital broadcasting system in the United States
In the TV (Advanced Television) standard, MPEG (Moving Picture Image Coding), which is an international standard for image compression.
Experts Group) will be adopted, and DVB (Digital Video Br
MPEG is about to be adopted also in oadcasting.

First, an outline of MPEG will be described. For MPEG encoding, motion compensation prediction, DCT
(Discrete cosine transform) and variable length coding are adopted. As shown in the frame structure of FIG. 9, an image is I (intra-coded) picture, P (predict
ive coded) picture, B (bi-directionally predictive)
coded) Pictures are classified into three types. The I picture is an intra-frame coded image, the P picture is an inter-frame predictive coded image predicted from a temporally preceding frame, and the B picture is an inter-frame predictive coded image from preceding and following frames.

FIG. 10 shows the MPEG data hierarchical structure.
Shown in It is configured as follows from the lower layer. (Block layer) A block is composed of adjacent 8 × 8 pixels of luminance or color difference, and DCT is executed in this unit. (Macroblock Layer) A macroblock is composed of four adjacent luminance blocks and two chrominance blocks Cb and Cr corresponding to the same position on the screen, for a total of six blocks. (Slice layer) It is composed of a plurality of macroblocks arranged in the scanning order of the image. (Picture layer) It is composed of a plurality of slices to form one image. It is classified into the above-mentioned I picture, P picture, and B picture according to the encoding format. (GOP (Group of Pictures) Layer) A GOP is composed of one or a plurality of I pictures and 0 or a plurality of non-I pictures. (Video Sequence Layer) A video sequence is composed of one or more GOPs having the same image size and image rate.

By the way, in recent years, a consumer digital VTR for recording video signals and audio signals in the form of digital signals has been developed. Next, a case of recording ATV standard data on the digital VTR will be described.

First, FIG. 11 shows a recording format of a digital VTR, in which each track is recorded in an ITI area consisting of insert data and track information in the order of recording.
It is composed of an audio data area, a video data area, and a subcode data area. And the magnetic tape is NTS
In the case of the C method, 300 tracks are recorded per second. Therefore, one frame image is recorded using an average of 10 tracks. In the case of PAL, 12 tracks will be used.

The data to be recorded is recorded in units called sync blocks, and 135 sync blocks can be recorded in the video area of one track. This sync block is shown in Figure 1.
As shown in 2, the recording area is composed of a sync area (2 bytes), an ID area (3 bytes), a data area (77 bytes) and a parity area (8 bytes), for a total of 90 bytes.

When recording MPEG data in the above-mentioned video data area, paying attention to a macroblock unit in which an input MPEG bit stream is sequentially recorded with the above-mentioned data layer, the code length of this macroblock is not constant. Moreover, since the information is recorded mixedly with the upper layer, there is no fixed relationship between the sync block and the recorded macro block. That is, the position of the data on the screen and the position of the recording track pattern are irrelevant.

When the magnetic tape recorded in this way is run at a speed different from that at the time of recording to perform special reproduction such as high-speed reproduction, the head scans over a plurality of tracks. Data can only be partially acquired. As described above, since the P picture and B picture in the MPEG bit stream are interframe predictive coded images, even if they are acquired in pieces, the images cannot be reconstructed.

That is, at the time of special reproduction, the image can be reconstructed only from the I picture which is the intra-frame predictive coded image. Further, in order to reconstruct an image of one I picture with high quality, it is necessary to obtain the data of the I picture distributed on the recording pattern as much as possible,
Special reproduction was impossible only by sequentially recording the input MPEG bit stream.

Therefore, as a conventional special reproduction method in a digital VTR, "A Recordin" of the academic journal "International Workshop On HDTV'93" issued in October 1993 was used.
g Method of ATV data on a Coqsumer Digital VCR ".

According to this method, in addition to the data for normal reproduction, the I picture data is recorded in the specific area as special reproduction data in the video data area. Such a recording method is possible because the data rate of ATV is about 19 Mbps, whereas the video data area of one track based on the consumer digital VTR is about 25 Mbps.
It is possible to record at a data rate of Mbps, so about 6M
This is because the area is left over by about bps.

Specifically, as shown in FIG. 13, special reproduction data areas TPA other than the normal reproduction data area NPA are provided at three positions in the front, center and rear of the video area. That is, 1-track video data area 135SB
Of the (sync blocks), for example, 32 SB in total is allocated as special reproduction data.

This trick play data allocation method is performed, for example, as shown in FIG. First, from the MPEG bit stream, I picture macroblock A,
B, C ... are extracted and data strings A ', B', C '.
・ ・ Get The code lengths of the encoded macroblocks are different. Then, the data strings A ′, B ′, C ′
Are sequentially assigned to the sync blocks SB1, SB2, .... At this time, since the sync block has a constant code length, there is no fixed relationship between each sync block and the assigned macro block, and one macro block extends over a plurality of sync blocks.

Then, as shown in FIG. 13, the maximum double speed number n
Allocate the same special playback data to the same number of tracks as. That is, when n = 5, the same data is inserted into the special reproduction data area TPA of 5 tracks.

Further, different data is set in units of 5 tracks, and this is repeated m times to record all the I picture data by 5 × m tracks.

When recorded in this way, if the reproduction speed is within 5 times, 5 m tracks will be recorded once for every 5 tracks.
By scanning once, a total of m times, it is possible to acquire all of the I picture data.

[0018]

However, according to the above method, an image can be reconstructed if all the data can be acquired within a limited number of scans. However, if the data acquisition rate is poor, the image is completely reproduced. There are cases where you cannot. Therefore, there is a drawback in that only a predetermined double speed number that can acquire all data can be supported.

The present invention solves the above drawbacks,
It is intended to provide a digital data recording method capable of high-speed reproduction at an arbitrary double speed number, and particularly to propose the same method capable of suitably supporting the DVB system in Europe.

[0020]

DISCLOSURE OF THE INVENTION The present invention provides a digital data recording method in which each track on a tape is divided into a plurality of data blocks and digital data is recorded.
In each of the data blocks, a first area for recording normal reproduction data and a second area for recording special reproduction data are formed, and a boundary between the first area and the second area is defined. This is a digital data recording method in which the data shown is recorded.

In the digital data recording method in which each track on the tape is divided into a plurality of data blocks and digital data is recorded, a first area for recording normal reproduction data in each of the data blocks. A second area for recording special reproduction data, a third area for recording data indicating a boundary between the first area and the second area, a sync data area for recording sync data, This is a digital data recording method in which an ID data area for recording ID data representing a position on a recording pattern of a data block is formed.

The special reproduction data is a digital data recording method in which only frame or field encoded image data of compressed image data is used.

Further, according to the present invention, each track on the tape is divided into a plurality of data blocks to record digital data, and in each of the data blocks, a first area for recording normal reproduction data and special reproduction are recorded. A recording area is provided with a second area for recording data for recording, and n blocks are repeatedly recorded with m tracks as one block, and the amount of digital data to be recorded per unit time is detected. A data amount detecting means, and a tape speed setting means for controlling the tape speed by selecting a tape speed capable of recording the detected data amount from a plurality of preset tape speeds based on the detection result of the data amount detecting means. , Receiving the output of the tape speed setting means,
Recording means for recording such that the areal recording density becomes substantially constant regardless of the set tape speed, and the number of times n of repeated recording of the block in which the special reproduction data is recorded is set to the tape speed setting. It is a digital data recording method which is set according to the tape speed at the time of recording obtained by the means.

Further, each track on the tape is divided into a plurality of data blocks to record digital data, and each of the data blocks has a first area for recording normal reproduction data and special reproduction data. A recording method in which a second area for recording is provided and the m tracks are recorded as one block, and each program data is recorded from the digital data so as to record digital data including a plurality of program data. Is a digital data recording method comprising program data selecting means for selecting special reproduction data, and alternately recording each program data obtained from the program data selecting means in block units.

According to the present invention, each track on the tape is divided into a plurality of data blocks to record digital data, and in each of the data blocks, a first area for recording normal reproduction data and special reproduction are recorded. A recording area is provided with a second area for recording data for recording and the m tracks are recorded as one block. In order to record digital data including a plurality of program data, Program data selection means for selecting each program data is provided, and normal reproduction data and special reproduction data included in each program data obtained from the program data selection means are alternately recorded in block units for each program. It is a digital data recording method.

[0026]

In the present invention, the normal reproduction data is the first data.
Is recorded in the area. The special reproduction data is recorded in the second area by associating the position on the screen with the position on the recording pattern. At that time, the boundary between the first area and the second area is determined by the data recorded in the third area,
The amount of data that can be recorded in the second area varies depending on the position of the boundary.

During normal reproduction, a normal reproduction image is obtained based on the data in the first area.

At the time of special reproduction, a special reproduction image is obtained based on the data of the second area of only the data block scanned by the head, but when the second area is large, more special reproduction data is recorded. Therefore, the quality of the special reproduction image is improved.

When recording is performed at different recording tape speeds depending on the bit rate to be recorded, the number of repetitions of the special reproduction data to be recorded changes to an appropriate number according to the tape speed.

When data of a plurality of programs are simultaneously sent in one bit stream, the special reproduction data of each program is alternately recorded in every predetermined block.

When data of a plurality of programs are simultaneously sent in one bit stream, the normal reproduction data and special reproduction data of each program are alternately recorded in predetermined blocks.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to the case of recording data transmitted by the DVB system in a consumer digital VTR will be described below with reference to the drawings.

First, the structure of the recording track in this embodiment will be described with reference to FIG. In this embodiment, for the sync block of the video data area 135, a special reproduction data area TPA and a normal reproduction data area NPA indicated by diagonal lines are provided in each sync block. Details of each sync block are shown in FIG. Sync block consists of sync area (2 bytes), ID area (3 bytes), data area (77 bytes) and parity area (8 bytes).
The basic structure of 90 bytes in total is the same as the conventional one, but 1 byte is used as the data area for the extra header (EH) in the data area, and the special playback data area TPA is Ntp bytes, normal playback. Data area N
PA is (76-Ntp) bytes.

That is, the normal reproduction data area NPA
And the boundary between the special playback data area TPA (NPSP)
Can be variably set according to the transmitted normal reproduction data, and the position of the boundary is recorded in the extra header.

As described above, the normal reproduction data area NP
Boundary between A and special playback data area TPA (NPS
P) can be variably set by the transmitted normal reproduction data for the following reason.

The transmission band for one channel of satellite broadcasting by the currently used analog system is 27 MHZ,
30 Mb when digital broadcasting is performed using this band
It is possible to transmit ps digital information.

On the other hand, the DVB method uses M as described above.
A signal is compressed by PEG, and a digital signal is transmitted at a variable rate of 1.5 to 20 Mbps. For example, if image information is transmitted at 5 Mbps per channel, it is possible to transmit a conventional one channel. It is possible to simultaneously perform 6-channel program distribution using the transmission band of, and so-called multi-channel is enabled.

Therefore, if the amount of normal reproduction data transmitted is small, the size of the data area for special reproduction can be increased accordingly. And
As the size of the data area for special reproduction increases, the amount of data for special reproduction recorded therein naturally increases. As a result, the quality of the special reproduction image can be improved.

For this reason, the normal reproduction data area NP is used according to the amount of the normal reproduction data transmitted.
Set the boundary between A and the special playback data area TPA,
The recording area of the digital VTR is effectively used.

The special reproduction data is assigned as shown in FIG. First, similarly to the conventional example, macroblocks A, B of an I picture from an MPEG bit stream
Extract C ... and extract data strings A ', B', C '...
Get. Here, the code lengths of the encoded macroblocks are different.

Next, MP each data string A ', B', C '.
The code length is set to have a predetermined code length according to the amount of normal reproduction data obtained from the EG bit stream. The DC component DC of the macroblock data subjected to DCT is almost constant in each macroblock, and the AC component AC.
Differs depending on the macroblock, and therefore the code length is limited so that the limited data of all the DC data and the AC data is summed to obtain the number of bytes.

Then, the data strings A ", B", C ", ...
1, SB2, ... Are assigned to the special reproduction data areas TPA. At this time, if the number of the sync block in one frame is recorded in the ID data area, it is possible to specify at which position on the screen the reproduction data is during reproduction.

As described above, since one macro block is assigned to each sync block, the position of the data on the screen and the position on the recording pattern have a fixed relationship. That is, it becomes possible to reconstruct the image of the specific portion on the screen from only the data of one sync block.

On the other hand, the normal reproduction data is input to the MP.
The EG bit stream is divided into (76-Ntp) bytes without limitation and sequentially allocated to the normal reproduction data area NPA following the special reproduction data area TPA of the sync block.

In the present embodiment, at the time of high speed reproduction, even if not all sync blocks can be acquired, if the sync area and ID area can be reproduced, the data of the sync block becomes valid, so the data area is set to be larger than that of NPA. By arranging the TPA so that it is close to the sync area and the ID area, the sync area, the ID area, and the TP
The probability that A can be scanned simultaneously increases.

In this embodiment, the data of one macroblock is assigned to one sync block, but a plurality of macroblocks may be assigned to one sync block or vice versa. . In short, it is only necessary that the macroblock data has a fixed relationship with the sync block.

FIG. 4 shows a recording track pattern of this embodiment. In the figure, the vertical direction is the track direction, and the horizontal direction is the tape running direction. For convenience of description, each track is not orthogonal to the tape but is orthogonal to the tape running direction.
The alphabet in the track indicates a frame, and the subscript indicates a sync block number. Further, in the figure, only the video data area is shown, and although there are actually 135 sync blocks for one track, the number is set to 7 for convenience.
In this case, all the data of one frame (I picture) can be recorded in 5 tracks. That is, the data of the frame A is recorded in the special reproduction data area TPA of the sync blocks a00 to a46. Further, one frame is made up of 5 tracks, and the same block is repeated m times. Therefore, data of the same frame is recorded over 5 × m tracks.

Further, in the ID data area, frame identification data, which switches between 1 and 0 each time the frame switches, is recorded. By reproducing this at the time of high-speed reproduction, it is possible to know the timing at which the frame has changed in the data string.

Incidentally, A and B at the upper end of the track respectively indicate the azimuth of the recording head.

Next, a case where the above-mentioned recording pattern is reproduced at 4 × speed will be described.

As shown in FIG. 4, the scanning of the A head and the B head facing each other by 180 °, for example, a00, aa01, a23, a24, a25 is obtained by one scanning of the A head, and the next B head is scanned. A01, a02, a0 in one scan
3, a25 and a26 are obtained. These data are shown in Figure 5.
It corresponds to a specific position on the screen as shown in. That is, the 2-digit number on the screen corresponds to the 2-digit subscript of the sync block in FIG. Here, the data of one track corresponds to a macroblock for one horizontal line on the screen.

Therefore, since the reproduced data from one sync block can reconstruct an image independently, m blocks (5 × m tracks) in which the data of the same frame is recorded are scanned a plurality of times to make all the blocks. If one can obtain different types of sync blocks, the entire screen can be reconstructed. Further, even if it is not possible to acquire all types of sync blocks, the screen can be reproduced to some extent according to the number of sync blocks acquired, so that the screen is easier to see than in the past.

Further, as shown in FIG. 6, when scanning a block of B frame, the data of B frame is accumulated in a buffer memory described later and the A frame previously accumulated from this buffer memory. Data is output. When a change in the frame identification data is detected, the buffer memory stores the C frame data and outputs the B frame data.

In this embodiment, there is no limitation on the reproduction speed and there is no influence on tracking deviation. The head structure may be a double azimuth structure.

Next, the recording processing circuit in this embodiment will be described with reference to FIG. First, M based on the DVB method
The PEG bit stream is input to the buffer memory 1, the I picture extracting circuit 2, and the normal data amount detecting circuit 22. In the buffer memory 1, the normal reproduction data NP is divided into 61 bytes for allocation to the normal reproduction data area of each sync block, and is output to the mixing circuit 3.

On the other hand, in the I picture extracting circuit 2, MPE
Of the G frame structure, only the I picture is extracted and divided into a DC component DC and an AC component AC for output. As shown in FIG. 3, the data input to the I-picture extracting circuit 2 is input in the order of macroblocks, and the bit stream of each block, which is a unit to which DCT is applied, has a DC component DC first, The AC components AC are arranged in order from the lowest frequency to the highest frequency, and the code length differs for each macroblock.

Here, in MPEG, since predictive coding is performed between blocks, that is, the encoded difference between the DC component of the current block and the DC component of the previous block is transmitted. Therefore, as it is, the DC component cannot be reproduced from only one macroblock. Therefore, the DC component DC from the I picture extracting circuit 2 is converted by the DC data conversion circuit 21 so that the DC component DC can be independently reproduced for each macroblock.

On the other hand, the normal data amount detection circuit 22 uses the MP
The amount of normal reproduction data obtained from the EG bit stream is detected, and the value detected here is the next Ntp determination circuit 23.
The size of the trick play data area is determined. The output of the Ntp determination circuit 23 is supplied to the code length control circuit circuit 4 and the extra header creation circuit 24.

Then, the code length control circuit 4 outputs DC and A for each macroblock by the output of the Ntp determination circuit 23.
Limit the total of C to Ntp bytes, and
The p bytes are supplied to the extra header creation circuit 24 in the next stage, and the header creation circuit 24 uses the Ntp determination circuit 2
In response to the output of No. 3, 1 byte of data indicating the amount of special reproduction data is added as an extra header before the Ntp byte and supplied to the buffer memory 5. By doing so, it becomes possible to allocate one macroblock to each sync block. Also, I
The picture extracting circuit 2 generates a flag once for each macroblock during extraction of an I picture. The counter 6 counts the flag for each I picture and outputs it as a macroblock number MB.

The buffer memory 5 is provided in parallel for two frames. The write address to the buffer memory 5 is controlled by the macro block number MB. The reading is controlled by the timing signal from the timing generation circuit 66. Specifically, the buffer memories A and B
The switch S1 is controlled based on the frame identification data, and writing and reading are alternately performed so that operations are not overlapped so that when one is writing, the other is reading. The output of the buffer memory 5 is mixed with the normal reproduction data NP in the mixing circuit 3 as special reproduction data TP to obtain a sync block structure as shown in FIG.

The output of the mixing circuit 3 is added with an error correction code by an error correction addition circuit 7, and then added with sync data and ID data by an addition circuit 8. Further, the ITI, audio data and sub-code are added by the additional circuit 9 in the subsequent stage to form data of a predetermined format, which is recorded on the tape.

Next, the reproduction processing circuit in this embodiment will be described with reference to FIG. First, the reproduction output from the tape is separated by the separation circuit 12 into ITI, audio data and subcode. The remaining data is further separated into sync data, ID data and extra header by the separation circuit 13 in the next stage. The error correction circuit 14 performs error correction on the data output from the separation circuit 13 by a known method. The separated extra header is output by the extra header detection circuit 25 as data at the boundary between the normal reproduction data NP and the special reproduction data TP, that is, data indicating the start point of the normal reproduction data. The data after error correction is separated into the normal reproduction data NP and the special reproduction data TP by the separation circuit 15.
This is performed by receiving the output of the header detection circuit 25. The normal reproduction data NP output from the separation circuit 15 is converted into a constant rate by the buffer memory 16 and output to the selector 17.

On the other hand, the trick play data TP is supplied to the buffer memory 18. The buffer memory 18 is provided in parallel for two frames, and writing and reading are alternately performed for A and B at a predetermined cycle. The write address of the buffer memory 18 is controlled based on the sync block number within one frame of the separated ID data. Further, as shown in FIG. 6, the writing to one buffer memory is performed during the period when the reproduction data from the same frame is obtained, and the switch S2 is turned off when the frame identification data in the ID data changes. With the change, the write operation and the read operation of each buffer memory are switched. This realizes the operation of FIG. The output of the switch S2 is sequentially supplied to the MPEG formatting circuit 19. Here, the layer above the macroblock is added to the special reproduction data TP to obtain M
MPEG that can be decoded by a PEG decoder (not shown)
Form the bit stream of the next buffer memory 2
Output to 0.

Then, in the buffer memory 20, the data is supplied to the selector 17 after being converted into a constant rate like the normal reproduction data NP. This selector 17 selects data according to a mode signal indicating normal reproduction or special reproduction and MPE
Output as a G bit stream.

As described above, in the DVB broadcasting system,
The bit rate of the transmitted digital information is MPE
The signal is compressed by G and the digital signal is transmitted at a variable rate of 1.5 to 20 Mbps.

On the other hand, in the digital VTR, if recording is performed in a mode of tape speed of 1 × speed, for example, 19.4.
Although Mbps recording is possible, when information is transmitted at a low bit rate (for example, 6 Mbps) in DVB broadcasting, a large amount of recordable area remains on the tape, resulting in waste of tape consumption.

An embodiment in which this point is improved will be described with reference to FIGS. 15 and 16. In FIGS. 15 and 16, the same parts as those in FIGS. 7 and 8 are designated by the same reference numerals, and the duplicate description thereof will be omitted.

In FIG. 15, the data amount detection circuit 30 detects the data amount per unit time of the MPEG bit stream signal, and the tape speed selection circuit 31 selects the tape speed mode based on the detection result. .
This tape speed mode has three types of modes: standard tape speed (standard speed mode), standard tape speed 1/2 (1/2 speed mode), and standard tape speed 1/4 (1/4 speed mode). It is assumed to be set in advance. In either mode, the recording is performed so that the areal recording density is substantially constant, as will be described later.
Assuming that a 9.2 Mbps bit stream can be recorded, a 9.6 Mbps bit stream can be recorded in the 1/2 speed mode, and a 4.8 Mbps bit stream can be recorded in the 1/4 speed mode. Therefore, the data amount of the MPEG bit stream detected by the data amount detection circuit 30 is 19.2 Mb.
Standard speed mode is selected when ps is less than or equal to 9.6 Mb
When ps or less, 1/2 speed mode is selected and 4.8M
When it is lower than bps, the 1/4 speed mode is selected.

A signal indicating the selected tape speed mode is output from the tape speed selection circuit 31 to the capstan and reel drive unit 32, whereby the capstan CA transfers the tape at the selected speed. The tape speed selection circuit 31 also outputs a signal indicating the selected tape speed mode to the recording timing generation circuit 66. The recording timing generation circuit 66 controls the timing of write data as described in the previous embodiment, and controls the switch S3 as described below to write on the tape T by the rotary head (double azimuth head) 35. Control the time period. The timing of writing on the tape will be described with reference to FIG.
In FIG. 17, the numbers enclosed by squares indicate the track numbers recorded by the double azimuth heads A and B, and S
Reference numeral 3 indicates the state of the switch S3 (ON at high level). In the standard speed mode, the switch S3 is always on as shown in the upper part of FIG. 17, and the tracks are simultaneously recorded as tracks 1 and 2 and tracks 3 and 4 at the cycle of one rotation of the cylinder. .

In this embodiment, since the cylinder rotation speed is constant, if the tape is always written, if the tape speed is halved, the recording track pitch becomes ½ and the area density becomes too large. Normal recording is not possible.

Therefore, the recording timing circuit has the switch S.
3 is controlled so that in the 1/2 speed mode, the switch S3 is closed and writing is performed on the tape only during one scanning of the double azimuth head 35 scanning the tape T twice. The recording track pitch and the areal recording density are made substantially constant (see the 1/2 speed in the middle part of FIG. 17). Similarly, in the 1/4 speed mode, the track pitch and the areal recording density are kept constant by closing the switch S3 and writing on the tape only once every four times the head scans (the lower part of FIG. 17). reference).

In this way, the recording timing generation circuit 66
Controls the memory control circuit 11 and the sync addition circuit 8 so as to output a recording signal in accordance with the opening and closing of the switch S3.

Reference numeral 34 is a modulation and recording amplifier for modulating and amplifying the output of the additional circuit 9, and this output is given to the head 35 via the switch S3.

Next, normal reproduction when recorded in the tape speed mode as described above will be described with reference to FIG.

First, the capstan CA is driven at a predetermined tape speed to reproduce a signal, and the separation circuit 13 separates the ID signal from the reproduced signal.
A tape speed detection circuit 36 detects the tape speed mode according to the D signal. The tape speed detection circuit 36
A signal indicating the detected tape speed mode is displayed on the capstan
As a result, the capstan CA transfers the tape at a tape transfer speed corresponding to the mode.

The reproduction timing generating circuit 37 generates a timing for opening / closing the switch S4 according to the detected tape speed mode. With this timing signal, as in the operation of the switch S3 at the time of recording, the switch S4 is always closed in the standard speed mode to pass all the reproduced signals, and the head is scanned twice in the 1/2 speed mode. The switch S4 is closed only during one scanning period, and in the 1/4 speed mode, the switch S4 is controlled to be closed only during one scanning period while the head is scanning four times. As a result, a signal having the same data rate as the recorded data rate is reproduced.

By the way, it is necessary to suitably perform special reproduction such as high-speed reproduction even if recorded in different tape speed modes as described above. Therefore, in the present invention, special reproduction data will be described below. I try to record it like this.

That is, in the case of recording in the standard speed mode, the switch S1 is switched, for example, every 12 × 37 444 tracks by a signal from the recording timing generation circuit 66. As described above, since the special reproduction data for one frame is recorded on 12 tracks, the special reproduction data for one frame is repeatedly recorded 37 times.

During special reproduction, the reproduction timing generation circuit 37 of the reproduction circuit always closes the switch S4 so that all reproduction signals can be used for special reproduction.

Therefore, the special reproduction data repeatedly recorded 37 times can reproduce all the special reproduction data in 12 tracks up to the special reproduction speed of 18.5 times the standard speed.

Next, in the case of recording in the 1/2 speed mode, the recording timing generating circuit 66 receives the tape speed data from the tape speed selecting circuit 31, and in this case 12 ×
The selection of the switch S1 is switched every time 228 tracks of 19 are written. In this case, special reproduction data for one frame is repeatedly recorded 19 times.

During special reproduction, the reproduction timing generation circuit 37 of the reproduction circuit always closes the switch S4 so that all reproduction signals can be used for special reproduction.

Therefore, when recording is repeated 19 times,
All special reproduction data in 12 tracks can be reproduced up to 9.5 times special reproduction speed of the standard speed mode.

Since the tape speed in the normal reproduction in the 1/2 speed mode is 1/2 of the standard speed mode, the tape speed 9.5 times that in the standard speed mode is 18 times the tape speed in the normal reproduction.
In the 1/2 speed mode, special reproduction can be performed at a speed 18 times the tape speed during normal reproduction, which is almost the same as in the case of recording in the standard speed mode.

Similarly, in the case of recording in the 1/4 speed mode, the recording timing generation circuit 66 receives the tape speed data from the tape speed selection circuit 31, and in this case, 12
The selection of the switch S1 is switched every time 108 tracks of × 9 are written. In this case, special reproduction data for one frame is repeatedly recorded 9 times.

When repeatedly recorded 9 times, all the special reproduction data in 12 tracks can be reproduced up to the special reproduction speed of 4.5 times the standard speed mode.

Since the tape speed in the 1/4 speed mode normal reproduction is 1/4 of the standard speed mode tape speed, 4.5 times the standard speed mode corresponds to 18 times the normal reproduction tape speed. Even in the case of recording in the 1/4 speed mode, it is possible to perform special reproduction 18 times as much as the normal reproduction, which is almost the same as in the case of recording in the standard speed mode.

Incidentally, FIG. 18A shows the standard speed mode, 1/2
A tape track pattern formed commonly in the high speed mode and the 1/4 speed mode is shown, and FIG. 6B shows a recording pattern of special reproduction data.

By thus configuring the number of times the special reproduction data is repeated according to the recording tape speed, the same special reproduction performance can be obtained even if recording is performed at different recording tape speeds according to the bit rate to be recorded. Can be obtained.

As described above, multi-channel broadcasting is considered in DVB, and one bit stream can include a plurality of programs in the MPEG bit stream.

An embodiment of a recording and reproducing method in which a plurality of programs are simultaneously recorded when one bitstream includes a plurality of programs will be described with reference to FIGS. 19 to 23. To do. 19 to 23, the same parts as those in FIGS. 7 and 8 are designated by the same reference numerals, and the duplicated description thereof will be omitted.

Now, the MPE input to the digital VTR
An example in which two programs, program A and program B, are included in the G bit stream and the two programs are recorded simultaneously will be described.

As data for normal reproduction, if a bit stream in which two programs are mixed is recorded as it is and reproduced, MPE is performed.
Since the program can be selected and decoded on the G decoder (not shown) side, the program can be recorded by the method described so far without being aware that it is two programs. Also, program selection during normal reproduction may be performed within the VTR before output to the decoder.

On the other hand, in the special reproduction data, the special reproduction data of two programs are separately recorded in order to record the positions on the screen in association with the recording positions.

FIG. 19 shows the method of recording the special reproduction data.
And it demonstrates based on FIG.

The input MPEG bit stream is
The program is input to the program selection circuit 40, where the program A and the program B are input.
Is separated into Each program data is input to the special reproduction data creation block for programs A and B provided below the I picture extracting circuit 2, 2 ', and special reproduction data for each program is created.

That is, the special reproduction data creation block circuit for the program A comprises the I picture extracting circuit 2, the DC data conversion circuit 21, the code length control circuit 4, the buffer memory 5, the counter 6, and the switch S1. The special reproduction data creation block circuit for the program B includes an I picture extracting circuit 2 ', a DC data converting circuit 21', a code length control circuit 4 ', a buffer memory 5', a counter 6 ', and a switch S1'. Both blocks perform the same operation. The switch S5 controlled by the control signal from the timing generation circuit 66 causes the switch S
1 and the output of the switch S1 ′ are selected and input to the mixer 3. When the trick play data is created, the trick play data of each program includes data indicating which program the trick play data is for each sync block. After being added to the special reproduction data of, the special reproduction data of each program is supplied to the switch S5.

Since one frame of special reproduction data can be recorded in the special reproduction data area of 12 tracks, the recording timing generation circuit 66 generates a switching signal to switch the switch S5 every 12 tracks. As shown in FIG. 20, program A and program B are recorded.

Next, a description will be given of a case where special recording such as high speed fast forward is performed on the recorded material as described above. Since the head scans over tracks during high speed reproduction, the program A and the program B can be scanned once. There is a case where special reproduction data for use is mixed and reproduced. Therefore, in the reproducing circuit, as shown in FIG. 23, during the special reproduction, the special reproduction data TP is separated by the separating circuit 15 and then the special reproduction program selecting circuit 4 is used.
If it is desired to perform special reproduction of program A in step 1, only the special reproduction data of program A is selected and the special reproduction buffer memory 18 is selected.
Input below and perform special playback of program A.

In this manner, in this embodiment, a plurality of programs can be recorded at the same time and the special reproduction of each program can be performed, but the data for normal reproduction are mixed and recorded as the input MPEG bit stream. Therefore, it is not possible to erase or overwrite only a specific program, for example, program A, once it has been recorded.

Therefore, next, a plurality of programs are recorded at the same time, and after recording once, only a part of the programs is erased.
An example in which overwriting is possible will be described with reference to FIGS. 21 and 22. In FIG. 21, the same parts as those in FIG. 19 are designated by the same reference numerals, and the duplicate description thereof will be omitted.

As in the previous embodiment, the program bit A and the program bit B are added to the MPEG bit stream input to the digital VTR.
A case where one program is included and two of them are recorded simultaneously will be described.

The bit stream in which two programs are mixed and inputted to the digital VTR is first transmitted to the program A by the program selection circuit 40.
And program B are separated. The normal reproduction data of the program A is once stored in the buffer 1 and read at the recording timing controlled by the recording timing generation circuit 66, and the normal reproduction data of the program B is once stored in the buffer 1'and controlled by the recording timing generation circuit 66. It is read at the recording timing that is set.

Regarding the special reproduction data, the MPEG bit stream separated for each program is input to the special reproduction data preparation block below the above-mentioned I picture extracting circuit, and the special reproduction data for each program is prepared.

For each program, the normal reproduction data and the special reproduction data are mixed by the mixing circuits 3 and 3 ', and data indicating whether each program is data is added to the data for each sync block. The normal reproduction data and special reproduction data of the program are supplied to the switch S5 '.

Since the special reproduction data can record one frame of data in the special reproduction data area of 12 tracks, the recording timing generation circuit 66 generates a switching signal for switching the switch S5 'every 12 tracks. Program A and program B are recorded as shown in FIG. In the normal reproduction data, the program A and the program B are switched every 12 tracks in accordance with the special reproduction data.

With such a configuration, as shown in the timing chart, the normal reproduction data and the special reproduction data of the specific program are recorded in the same area, so that after recording once, only the specific program may be erased. It can be overwritten.

In the case of special reproduction such as high speed fast forward, the above-mentioned plural program recording system is exactly the same as that shown in FIG.
The circuit of 3 can be used to perform special reproduction of a specific program.

In this way, it is possible to record a plurality of programs at the same time and perform special reproduction of each program. After recording once, it is possible to erase or overwrite only a specific program, for example, program A. .

In the embodiment, only the case of two programs has been described, but if the number of circuit blocks is increased, it is possible to record a plurality of programs at the same time.

[0111]

As described above, according to the present invention, since the special reproduction data is distributed and arranged in the tracks, excellent special reproduction can be performed regardless of the head arrangement, the tape reproduction speed and the tape feed phase.

Further, since the special reproduction data to be recorded is made variable according to the amount of the normal reproduction data, there is an advantage that the special reproduction data can be effectively recorded.

By recording the position on the recording pattern and the position on the screen in association with each other, the screen can be reconstructed in data block units.

By dividing the special reproduction data for one frame into a plurality of tracks and recording the data of the same frame a plurality of times repeatedly, a larger number of data blocks in the same frame can be obtained. It is possible to obtain special reproduction images with a lot of noise.

Further, by adding the frame identification data to each data block, one image can be constructed based on only the data in the same frame at the time of special reproduction, so that there is no discontinuity in the screen and it is easy to see. .

Further, by configuring the number of repetitions of the special reproduction data according to the recording tape speed, the same special reproduction performance can be obtained even if recording is performed at different recording tape speeds according to the bit rate to be recorded. Obtainable.

Further, even when a plurality of programs are sent at the same time, the recording is performed and the special reproduction of each recorded program is possible.

Further, by recording the normal reproduction data and the special reproduction data of the program in the same area,
After recording once, only specific programs can be erased or overwritten. In the case of special reproduction such as high-speed fast-forward, special reproduction of a specific program can be performed by the same method as the above-described plural program recording method. In this way, a plurality of programs can be recorded at the same time, and special reproduction of each program can be performed. After recording once, only a specific program, for example, the program A can be erased or overwritten. , Video editing can be done easily.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of sync blocks according to the present embodiment.

FIG. 3 is a diagram showing a method of allocating special reproduction data in this embodiment.

FIG. 4 is an explanatory diagram of head scanning during high-speed reproduction according to this embodiment.

FIG. 5 is an explanatory diagram of a reproduction screen during high-speed reproduction according to this embodiment.

FIG. 6 is an explanatory diagram of frame identification during high-speed reproduction according to this embodiment.

FIG. 7 is a block diagram of a recording processing circuit in this embodiment.

FIG. 8 is a block diagram of a reproduction processing circuit according to the present embodiment.

FIG. 9 is a diagram showing a frame structure of MPEG.

FIG. 10 is a diagram showing a data hierarchical structure of MPEG.

FIG. 11 is a diagram showing a recording track pattern in a conventional example.

FIG. 12 is an explanatory diagram of a sync block in a conventional example.

FIG. 13 is an explanatory diagram of head scanning during high speed reproduction in a conventional example.

FIG. 14 is an explanatory diagram of a trick play data allocation method in a conventional example.

FIG. 15 is a block diagram of a recording processing circuit according to a second embodiment of the present invention.

FIG. 16 is a block diagram of a reproduction processing circuit according to a second embodiment of the present invention.

FIG. 17 is an operation explanatory diagram of the block diagram of FIG. 15.

FIG. 18 is an operation explanatory diagram of the block diagram of FIG. 15;

FIG. 19 is a block diagram of a recording processing circuit according to a third embodiment of the present invention.

FIG. 20 is an operation explanatory diagram of the third embodiment.

FIG. 21 is a block diagram of a recording processing circuit according to a fourth embodiment of the present invention.

FIG. 22 is an operation explanatory diagram of the fourth embodiment.

FIG. 23 is a block diagram of a reproduction processing circuit according to third and fourth embodiments of the present invention.

[Explanation of symbols]

 NPA Normal reproduction data area TPA Special reproduction data area 2 I picture sampling circuit 4 Code length control circuit 6 Counter 19 MPEG formatting circuit 22 NP data amount detection circuit 24 Extra header addition circuit 30 Data amount detection circuit 31 Tape speed selection Circuit 40 Program selection circuit

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Ohnaka 2-5-5 Keihan Hondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Tatsuo Tanaka 2-5 Keihan-hondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd.

Claims (6)

[Claims] 1. A digital data recording method for recording digital data by dividing each track on a tape into a plurality of data blocks, wherein a first area for recording normal reproduction data in each of the data blocks. And a second area for recording special reproduction data, and a data recording method for recording data indicating a boundary between the first area and the second area. 2. A digital data recording method for recording digital data by dividing each track on a tape into a plurality of data blocks, wherein a first area for recording normal reproduction data in each of the data blocks. A second area for recording special reproduction data, a third area for recording data indicating a boundary between the first area and the second area, a sync data area for recording sync data, A digital data recording method comprising forming an ID data area for recording ID data representing a position on a recording pattern of a data block. 3. The digital data recording method according to claim 1, wherein only the frame or field encoded image data of the compressed image data is used as the special reproduction data. 4. Each track on the tape is divided into a plurality of data blocks to record digital data, and each of the data blocks has a first area for recording normal reproduction data and special reproduction data. A recording method in which a second area for recording is provided and n blocks are repeatedly recorded with m tracks as one block, and a data amount detection for detecting a data amount of digital data to be recorded per unit time A tape speed setting means for controlling the tape speed by selecting a tape speed capable of recording the detected data amount from a plurality of preset tape speeds according to the detection result of the data amount detecting means; Receiving the output of the speed setting means, recording is performed so that the areal recording density becomes almost constant regardless of the set tape speed. A digital data recording method, comprising: recording means, wherein the number of times of repeated recording n of the block in which the special reproduction data is recorded is set according to the tape speed at the time of recording obtained by the tape speed setting means. 5. Each track on the tape is divided into a plurality of data blocks to record digital data, and in each of the data blocks, a first area for recording normal reproduction data and special reproduction data are recorded. A recording method in which a second area for recording is provided, and the m tracks are recorded as one block, and each program data is recorded from the digital data so as to record digital data including a plurality of program data. The program data selection means for selecting the special reproduction data, and the digital data recording method for alternately recording the program data obtained from the program data selection means in block units. 6. Each track on the tape is divided into a plurality of data blocks to record digital data, and in each of the data blocks, a first area for recording normal reproduction data and special reproduction data are recorded. A recording method in which a second area for recording is provided, and the m tracks are recorded as one block, and each program data is recorded from the digital data so as to record digital data including a plurality of program data. Digital data comprising program data selecting means for selecting, and normal recording data and special reproduction data included in each program data obtained from the program data selecting means are alternately recorded in block units for each program. Recording method.