KR0135795B1 - Digital video tape recording method for trick play and the recording and reproducing apparatus - Google Patents

Abstract

The present invention relates to a method for recording a digital video tape, comprising: converting an ATV signal transmission packet into a sync block of an SD digital video tape recording format and recording normal and trick play data in the video sector of each track. The normal play data and the trick play data are recorded, but each track having the first azimuth is scanned at least once in the trick play at each speed at the first trick play data which is used in common at the trick play at all speeds set. A plurality of sync blocks are recorded in a predetermined position, and the normal play data is recorded in a remaining area, and each track having a second azimuth is commonly used in trick play at a specific speed or less. The trick play data is changed at least once during trick play at the specified speed or less. The normal play data is recorded in a plurality of sync blocks at a predetermined position, and the normal play data is recorded in the remaining area, and the first and second trick play data of the respective tracks are composed of data of an intra frame, The same data is recorded repeatedly in the tracks.

Therefore, the present invention can further improve the image quality at low speed compared to the high speed by additionally recording trick play data for low speed on the track having the first azimuth.

Description

Digital video tape recording method and its recording and reproducing apparatus for trick play

1 is a diagram showing a recording format of a digital video tape according to the present invention.

FIG. 2 is a diagram showing a recording format of a video sector of track f0 of FIG.

3 is a diagram for explaining conversion of an ATV signal transmission pocket into a sync block of an SD digital video tape.

4 is a diagram for explaining error correction decoding of normal play data.

5 is a diagram for explaining error correction decoding of trick play data.

6 is a block diagram of a recording apparatus according to the present invention.

7 is a block diagram of a playback apparatus according to the present invention.

8 is a view showing the scan trajectory of the two-head scanner during 8.5x trick play according to the present invention.

9 is a view showing scan trajectories of a double azimuth head and a double azimuth head during 8.5 times trick play according to the present invention.

10 is a table showing the numbers of common sink blocks obtained by experimentally obtaining an area common to all scanners of the first and second trick play data according to the present invention.

The present invention relates to a method of recording a digital video tape and a recording and reproducing apparatus thereof, and more particularly to a method of recording video data for trick play in a digital video tape recording / reproducing apparatus for recording and reproducing an ATV (Advanced TeleVision) signal. It relates to a recording and reproducing apparatus.

The development of consumer digital video tape players (hereinafter referred to as DVCR) for recording and reproducing ATV (Advanced TeleVision) signals on digital video tapes is in progress. The problem with the development of DVCR is how to take a recording format for special playback that can meet both picture quality and cost.

One approach is to arrange the trick play data in the scan area corresponding to each double speed. This method has a good picture quality of the trick play playback screen, but must scan the corresponding arrangement area, which involves servo control of speed lock, pager lock, and track select, resulting in a cost increase due to the burden of hardware design.

Another approach is to repeatedly record the trick play data to be recorded in a pair of tracks on tracks corresponding to a double speed. Since this method only needs to scan in the repetitive recording area, only the speedlock servo control is required, thereby reducing the hardware design burden. However, there is a problem of consuming a large recording area due to repetitive recording, and at a low speed compared to a high speed, the time for freezing a screen becomes longer, resulting in tedious and poor image quality at a low speed. There was a problem that was unobtrusive.

Disclosure of the Invention An object of the present invention is to provide a method of recording a digital video tape for a trick play that can satisfy both the servo control burden of a corresponding recording method and a low image quality deterioration of a repetitive recording method in order to solve the problems of the related art. The present invention provides a playback device under recording.

In order to achieve the above object, the recording method of the present invention is a method of recording normal and trick play data by converting a transmission packet of an ATV signal into a sync block of an SD digital video tape recording format. Data and trick play data are recorded, but for each track having a first azimuth, the first trick play data which is used in common at all times of trick play set up to a maximum N times or less includes at least one trick play data at each trick play speed. It is distributed once in a plurality of sync blocks at a predetermined position to be scanned, and the normal play data is recorded in the remaining area, and each track having a second azimuth is set at all speeds below a specific M (MN) speed. The second trick play data which is commonly used in trick play is when the trick play is below a specific double speed. At least once, distributed recording is performed in a plurality of sync blocks at a predetermined position to be scanned, and the normal play data is recorded in the remaining area, and the first and second trick play data of each track are composed of data of intra frames, The same data is repeatedly recorded in the number of tracks.

Herein, the maximum speed is an integer speed and the specific speed is less than the decimal speed. The transport packet is reconstructed with five sync blocks of data of two packets, five 1 byte headers and two 3 byte picture classification information. Each 1-byte header includes normal / trick 1 / trick 2 identification information, sequence information of each sync block, and toggle information of a repeating unit. Each of the 3 byte picture classification information includes the same screen identification information during the trick play. In the normal play data, data of a pair of tracks having different odd numbers is used as a sync block error correction unit. The trick play data uses a specific number of sync blocks as sync block error correction units.

The recording apparatus of the present invention comprises a recording buffer for buffering a transport stream of an ATV signal, a first sync block generator for reading data from the recording buffer, and adding sync data to form a sync block of the SD recording format; An error correction encoder for adding error correction information of a plurality of supplied sync blocks, a data extraction unit for extracting an intra frame corresponding to the maximum speed of the header information and trick play from the transport stream of the ATV signal, and an extracted intra frame A data separator for separating and outputting the first trick play data and the second trick play data from the data, a buffer for buffering the separated data, and reading the data from the buffer to form first and second trick play sink blocks. A second sink block former and a plurality of sink blocks supplied from the sink block former; A second error correction encoder for adding error correction information, normal play sync blocks to which an error correction code is added, and first and second trick play sync blocks to which the error correction code is added, according to track and sync block mapping. And a mapping unit for selectively outputting, a third error correction encoding unit for SD error correction encoding the mapped sync blocks, and a channel modulation unit for channel modulating the error corrected data and recording the same on a standard definition digital video tape.

The playback apparatus of the present invention includes a first error correction decoding unit for decoding and demodulating the demodulated data into SD error correction, normal play sync blocks and first and second trick play sync blocks with error corrected data according to track and sync block mapping. A demultiplexer that separates the signal, a second error correction decoder that error corrects the separated normal play sync blocks, a playback buffer that buffers the error corrected sync blocks, and error correction of the separated first and second trick play sync blocks. A third error correction decoding unit configured to perform a fast trick play playback buffer buffering the error corrected first trick play sync block, a low speed trick play playback buffer buffering the error corrected first and second trick play sync blocks; A first information appender for appending additional information to data read from the fast trick play playback buffer; and from the low speed trick play playback buffer. A second information adding unit for connecting the corresponding first and second trick play data and adding additional information to the data, and outputting from the playback buffer and the first and second information adding units according to a normal / trick play mode. And a data selector for selecting data to be output as a transport stream of the ATV signal.

Accordingly, the present invention can reduce the burden of the servo control by reducing the burden of the servo control by regenerating both the first and second wrong play data from the tracks having the first and second azimuths by a simple speed lock control at a speed lower than a specific speed. Can improve the quality of reproduction.

Hereinafter, with reference to the accompanying drawings will be described in more detail the present invention.

1 shows a track structure of a digital video tape for recording an SD (Standard Definition) -ATV signal. In FIG. 1, the tracks are divided in the order of the ITI sector 2, the audio sector 4, the video sector 6, and the subcode sector 8 from the scanner, i.e., the track start at which the head starts scanning. There is a gap between each sector. The ITI sector 2 includes a preamble area, a start sync block area, a track information area and a postamble area. The subcode sector 8 includes a preamble area, a subcode area, and a postamble area. The area after the subcode sector 8 is an overwrite margin. A track with + azimuth has a frequency characteristic of f 0, and a track with azimuth has an alternating frequency characteristic of f 1 and f 2. This frequency feature is the frequency feature of the bit stream recorded on each track. There are five first trick play data areas 10 in each video sector 6 of the f0 tracks. In the first trick play data area 10, trick play data consisting of header information of intra frame data and DC information of a DCT block is recorded. In the video sectors other than the first trick play data area 10, a normal play data area 12 is used, and 13 is an error correction data area of normal play data. 14 is an error correction data area of the SD format. There are three second trick play data areas 16 in each video sector 6 of the f1 and f2 tracks. In the second trick play data area 16, trick play data composed of variable length coding (VLC) data of some AC information of a DCT block of intra frame data is recorded. Here, the number of VLC data is preferably about two corresponding to the AC information of the low frequency component. In the video sectors other than the second trick play data area 16, a normal play data area 12 is used, and 13 is an error correction data area of normal play data. Here, the first and second trick play data areas are determined by experimentally obtaining an area in which the two-head scanner, the double azimuth scanner and the two-double azimuth scanner are commonly scanned as shown in the table of FIG. Therefore, at the speed of 8.5 times, the first trick play data areas 10 on the track f0 are preferably 41-45, 63-67, 84-88, 105-109, 127-131 in terms of sync block numbers, and f1 or The second trick play data areas 16 in the f2 track are preferably 61-65, 52-86, 103-107 in terms of sync block numbers.

2 shows the structure of the video sector of the f0 track of the digital videotape according to the present invention. The video sector 6 is composed of 149 sync blocks. That is, 19-20 sync blocks as the first video auxiliary data area 21, 25 sync blocks as the five first trick play data areas 22, and 100 sync blocks as the normal play data area 23. 10 error correction sync blocks for normal play data, one sync block as the second video auxiliary data area 24, and 157-167 sink blocks as the error correction outer code area 25. Each sync block is composed of a 2-byte sync code 26, a 3-byte identification code 27, a 77-byte data 28, and an 8-byte error correction inner code parity 29.

Referring to FIG. 3, two transmission packets of 188 bytes of the ATV signal are reconstructed and recorded into five sync blocks of the SD recording format. The transmission packet 30 is composed of 1 byte of sync byte and 187 data bytes. Thus, in order to divide and reconstruct 374 bytes of two transmission packets into 5 sync blocks having 77 * 5 = 385 bytes of data bytes, 5 headers 31 of 1 byte and 2 picture classification information of 3 bytes are used. It is comprised by adding 32. Each header 31 of one byte has information for distinguishing whether it is normal play data, first and second trick play data or dummy data by upper two bits, and the least significant bit has trick play repeat toggle information. In the case of trick play data, 5 bits have information indicating the order of 30 sink blocks, which is an error correction unit. The picture classification information 32 has the same screen information, and at the time of trick play, this information identifies whether it is one screen data of the trick play.

Referring to FIG. 4, normal play data includes +100 sync blocks of azimuth track and 210 sync blocks of 110 sync blocks of azimuth track to 20 error correction sync blocks for normal play data. Error correction and decoding. Referring to FIG. 5, the first and second wrong play data constitute an error correction decoding processing unit with 30 sync blocks. In the case of the trick play at the maximum speed, for example, 18 times, the first trick play data sync blocks of the track f0 are collected by 30 to perform error correction decoding with the 25 data sync blocks 50 and the five error correction sync blocks 51. do. In trick play at a specific speed, for example, 8.5 times or less, the data of the second trick play data sync blocks are combined and reproduced with the data of the corresponding first sync block.

Referring to FIG. 6, the recording apparatus of the present invention is a recording buffer 62 for buffering a transport stream of an ATV signal, and the sink and identification information and error correction internal code of the sync block after reading data from the recording buffer 62. Error correction for adding error correction information of the first sync block former 64 to form the sync block of the SD recording format by adding additional data such as the second sync block, and the plurality of sync blocks supplied from the first sync block former 64; An encoder 66, a data extractor 68 for extracting an intra frame corresponding to the maximum speed of the header information and trick play from the transport stream of the ATV signal, and a DC coefficient and a header of the DCT block from the extracted intra frame data. In the case of DC, the first trick play data composed of information and the second trick play data composed of an AC number of the DCT block are output separately, respectively, to reduce the data bit rate. The data separator 70 forms data without an EOB, which is a block termination code, and adds an EOB if VLC is 2 or less, and otherwise forms an EOB, and a buffer buffering the separated data. ), A second sync block former 74 that reads data from the buffer 72 to form first and second trick play sync blocks, and a plurality of sink blocks supplied from the second sync block former 74; The second error correction encoding unit 76 which adds error correction information, the normal play sync blocks to which an error correction code is added, and the first and second trick play sync blocks to which the error correction code is added, are shown in FIG. A mapping unit 78 for selectively outputting according to the track and sync block mapping signal TM according to the arrangement of the invention, a third error correction coding unit 80 for SD error correction encoding the mapped sync blocks, Error definition The SD of the data channel modulated in a channel modulator 82 for recording on the SD digital video tape 84.

Referring to FIG. 7, the playback apparatus according to the present invention includes a channel demodulator 86 for channel decoding a signal picked up from an SD digital video tape 84 to generate demodulated data, and correcting the SD error with the demodulated data. A first error correction decoding unit 88 to decode, and a demapping unit 90 which separates the error corrected data according to the selected play into a normal play sync block and first and second trick play sync blocks. A second error correction decoder 92 for error correcting normal play sync blocks, a reproducing buffer 94 for buffering error corrected sync blocks, and a first error correcting first and second trick play sync blocks. 3 The error correction decoding unit 96, the fast trick play reproducing buffer 98 buffering the error corrected first trick play sync block, and the slow trick play buffering the error corrected first and second trick play sync blocks.A first information addition section 102 for adding additional information of the EOB, the end code of the DCT block, to the data read from the playback buffer 100 and the fast trick play playback buffer 98, and a corresponding read from the low speed trick play playback buffer. A second information appending unit 104 which connects the first and second trick play data and adds additional information of the EOB to the data having no EOB, and the playback buffer 94 and the first and first in accordance with the normal / trick play mode. 2 includes a data selector 106 which selects data output from the information adding units 102 and 104 and outputs the data to the transport stream of the ATV signal.

Referring to Fig. 8, the trajectory when the ATV recording SD digital video tape according to the present invention is scanned by a 8.5-fold double-head scanner is shown. When 18 times the maximum speed, the first trick play data is recorded in 18 + azimuth tracks corresponding to 18 times the speed. Thus, 36 + and-azimuth tracks have a repetition period. That is, the same first trick play data is recorded in 18 + azimuth tracks out of 36 tracks. Similarly, the same second false play data is recorded in eighteen azimuth tracks. That is, the contents of the first and second wrong play data are different for every 36 tracks. One screen data during normal play is recorded in ten tracks (12 tracks in the 625 scan line method) in the case of the 525 main line method. If one screen group is composed of 15 screens and one intra frame consists of trick play data for every 10 screen groups, one screen trick play screen is played for 150 screens of normal play. Therefore, one piece of trick play data is repeatedly divided into approximately 42 pieces every 36 tracks over 1500 tracks. Therefore, in the 8.5-times trick play of FIG. 8, the first trick play data is picked up by the + azimuth head, and the second trick play data is picked up by the azimuth head, and these first and second trick plays are picked up. The data is combined to form a 8.5x trick play screen. In the drawing, the first trick play data is picked up at 1-3-5 and 2-4 and the second trick play data is picked up at 1-3 and 2.

9 shows scan trajectories in the case of the scanner of the double azimuth head method and the double azimuth head method. The solid line is the scan trajectory of the double azimuth method, and the case where the solid line and the dotted line are combined is the scan trajectory of the 2 double azimuth method. Meanwhile, the first trick play data is picked up at 2-4 and 1-3-5, and the second trick play data is picked up at 1-3 and 2.

In the present invention, a decimal point speed of 18 times speed, -16 times speed, or less than +/- 8.5 times speed is possible. Only the first trick play data is reproduced at 18 / -16 times, but the first and second trick play data are reproduced at decimal speeds of 8.5 times or less, so that the image quality is improved compared to the high speed.

As described above, in the present invention, in recording the ATV signal to the SD digital video tape, the first trick play data that can be picked up at all speeds in order to reproduce the playback screen at the time of trick play at multiple speeds is the maximum speed number. + In order to improve the image quality at low speeds below a certain speed, only the information of DC coefficient of DCT block is repeatedly recorded on azimuth tracks. By selecting both the DC and AC information with speed lock control, the playback screen can be configured to improve the screen quality and reduce the servo control burden during trick play.

Claims (9)

A method of recording normal and trick play data by converting an ATV signal transmission packet into a sync block of an SD digital video tape recording format, The normal play data and trick play data are recorded in the video sector of each track, Each track having a first azimuth has a plurality of sync blocks at a predetermined position where first trick play data which is used in common at the time of trick play at all double speeds is scanned at least once during trick play at each double speed. Distributedly recorded and the normal play data is recorded in the remaining area, Each track having a second azimuth has a plurality of sync blocks at a predetermined position where second trick play data which is commonly used in trick play at a specific double speed or less is scanned at least once in trick play at or below the specific double speed. Are recorded in a distributed manner, and the normal play data is recorded in the remaining area. And the first and second trick play data of the tracks are composed of intra frame data, and the same data is repeatedly recorded on the tracks of the highest double speed. The recording method according to claim 1, wherein the double speed is the maximum double speed and the double speed is less than the specified double speed. The recording method as claimed in claim 1, wherein the transmission packet comprises five sync blocks of data of two packets, five 1-byte headers, and two 3-byte picture classification information. 4. The recording method of claim 3, wherein each of the headers includes normal / trick 1 / trick 2 identification information, sequence information of each sync block, and toggle information of a repeating unit. 4. The recording method as claimed in claim 3, wherein each of the picture classification information includes the same screen identification information during traffic play. The recording method as claimed in claim 1, wherein the normal play data comprises a pair of tracks having different azimuths as sync block error correction units. The recording method as claimed in claim 1, wherein the trick play data comprises a specific number of sync blocks as sync block error correction units. A recording buffer for buffering the transport stream of the ATV signal; A first sync block former for reading data from the write buffer and adding sync data to form a sync block of the SD recording format; An error correction encoder for adding error correction information of a plurality of sink blocks supplied from the sink block former; A data extraction unit for extracting an intra frame corresponding to the maximum speed of the header information and the trick play from the transport stream of the ATV signal; A data separation unit for dividing the first trick play data and the second trick play data from the extracted intra frame data and outputting them separately; A buffer for buffering the separated data; A second sync block former that reads data from the buffer and forms first and second trick play sync blocks; A second error correction encoder for adding error correction information of a plurality of sink blocks supplied from the sink block former; A mapping unit for selectively outputting normal play sync blocks to which the error correction code is added and first and second trick play sync blocks to which the error correction code is added according to track and sync block mapping; A third error correction encoder which encodes the mapped sync blocks with SD error correction; And And a channel modulator for channel modulating error-corrected data and recording the same on a standard definition digital video tape. A first error correction decoding unit for decoding the demodulated data into the SD error correction decoding unit; A demultiplexer for separating error corrected data into normal play sync blocks and first and second trick play sync blocks according to the track and sync block mapping; A second error correction decoder configured to error correct the separated normal play sync blocks; A playback buffer for buffering error corrected sync blocks; A third error correction decoder configured to error correct the separated first and second trick play sync blocks; A fast trick play playback buffer buffering the error corrected first trick play sync block; A low speed trick play reproducing buffer buffering the error corrected first and second trick play sync blocks; A first information unit for adding additional information to the data read from the fast trick play playback buffer; A second information unit for connecting the corresponding first and second trick play data read from the slow trick play playback buffer and adding additional information to the data; And And a data selector for selecting data output from the playback buffer and the first and second information units according to a normal / trick play mode and outputting the data as a transport stream of an ATV signal.