KR0165298B1 - Recording/reproducing apparatus and method thereof - Google Patents

Abstract

The present invention discloses a format, recording and reproducing method of digital videotape for trick play, and apparatuses thereof. The format is divided into first, second and third areas of the video sector data area, and then normal play data is selected in the first area, and the trick play data selected in response to the highest even speed (N) among the plurality of even speeds in the second area. The DC component is repeatedly recorded at a 2N track interval, and the AC component of the trick play data is repeatedly recorded at a multiple track interval of M (MN, which is an even number among N's divisors) in the third region. And processing the play data as unencoded data, correcting an error, and modulating the error data. The reproducing method includes encoding after the error correction of the trick play data reproduced on a tape, encoding the temporary data, and supplying the ATV to the ATV after temporary storage. And recording means receives the frame data of the ATV signal, processes the trick play data into unencoded data, and modulates the data after error correction. And a means for correcting the error of the trick play data reproduced from the tape, encoding and supplying it to the ATV, and displaying at least a DC value in the high speed trick play. In this case, it is possible to obtain high resolution trick data at low speed, to eliminate the need to record additional information according to encoding, and to prevent error propagation that may be serious due to encoding on the tape.

Description

Format, recording and playback method of digital videotape for trick play and apparatus thereof.

1 is a diagram showing a track format of a digital video tape having a recording format of an SD-VCR.

FIG. 2 shows the head structure and track scan trajectory of the two head scanner for reproducing the signal recorded in the track shown in FIG.

3 is a diagram for clarifying coefficient division of each DCT block of the selected trick play frame data according to the present invention.

4 is a diagram showing the format of tracks in a tape according to the present invention.

FIG. 5A is a diagram illustrating an exemplary embodiment for repeating the trick play data on a plurality of tracks of a digital video tape according to the present invention.

FIG. 5B is a diagram illustrating another embodiment for explaining repetitive arrangement of trick play data on a plurality of tracks of a digital video tape according to the present invention.

FIG. 6 is a diagram for explaining a pattern in which a two-head scanner scans a digital video tape when playing up to 20 times the speed of trick play data recorded in the middle of a video area.

FIG. 7 is an embodiment illustrating a pattern in which a two-head scanner scans a digital video tape during low-speed play of trick play data recorded in the middle of the video area.

8 is a block diagram showing an apparatus for recording trick play data on a tape in a digital video tape according to the present invention.

FIG. 9 is a detailed block diagram of the signal processor shown in FIG. 8 according to the present invention.

10 is a block diagram of a playback apparatus for reproducing trick play and normal play data recorded on a digital video tape according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a format of a digital video tape, a recording and reproducing method, and apparatuses thereof. In particular, the present invention relates to digital video tape for trick play in a digital video tape that records and reproduces an Advanced TeleVision (ATV) signal. And a method and apparatus for recording and reproducing.

The development of consumer digital video tape players (hereinafter referred to as DVCRs) for recording and reproducing ATV (Advanced TeleVision) signals to SD (Standard VCR) -VCR digital video tapes is underway. The bit stream of the SD-VCR is 24.9 megabits per second, but the ATV signal is 19.3 megabits per second, leaving an area for recording 5.6 megabits per second. Research is underway on how to use the remaining video sector and the unused audio sector to meet the trick play speed, to satisfy all types of scanners, and to improve image quality and noise issues.

The present invention proposes one approach to one of these studies on how to implement a home digital video tape player where it is desirable to record trick play data using which device.

The problem in the development of such DVCR is how to take a recording format for special playback that can satisfy both image quality and cost.

One approach to this is to arrange the trick play data in a scan area corresponding to each double speed. This method has a problem that the cost is increased due to the burden of precise control of the servo since the image quality of the play screen for trick play is excellent but the corresponding arrangement area must be scanned.

Another approach is to repeatedly record trick play data to be recorded in a pair of tracks on tracks corresponding to a double speed. This method does not require accurate servo control because it only needs to scan in the repetitive recording area, so there is no problem of cost increase, but there is a problem of consuming a large recording area by repetitive recording. The longer the freezing time is, the less boring it feels at low speeds and the more uncomfortable if the picture quality is poor. In the past, the trick data when recording ATV (Advanced TeleVision) signals to SD-VCR digital videotape. The length of the head is recorded on the tape too much, and the variable length coding (VLC: Variable Length Coding) is used to allocate the bit in the screen so that the trick image is less than a certain number of bits. In addition, when an error that is difficult to correct on the tape occurs, error propagation There were problems that became serious.

Disclosure of the Invention An object of the present invention is to provide a digital video tape format, a recording and reproducing method, and an ATV signal for SD-Trick. There is provided a recording apparatus for quantizing and recording a variable-length encoding on a digital video tape of a VCR, and a reproducing apparatus for reproducing and encoding the recorded data.

In order to achieve the above object, the format of a digital video tape for trick play according to the present invention is divided into normal play data and trick play data by dividing the ATV signal including frame data which are supplied at predetermined intervals and independently decodable. In the tape format, the data area of the video sector of each track of the digital video tape is divided into a first area, a second area and a third area, and the normal play data is recorded in the first area. In the second area, a DC component of the trick play data, which is the frame data selected corresponding to the highest even speed N among a plurality of given even speeds, is recorded at 2N track intervals, and the third area exchanges the trick play data. The components are repeatedly written at track intervals of multiples of M (MN and even divisors of N). And it characterized in that.

Therefore, the present invention can improve image quality by recording trick play data for low speed in the video sector.

In order to achieve another object of the present invention, a method for recording a digital video tape for trick play according to the present invention temporarily stores normal play data in an ATV signal including frame data which is supplied at predetermined intervals and independently decodable, and performs tricks. A storage and signal processing step of processing play data as unencoded data, a first selection step of selecting normal play data or trick play data, and an error correction step of correcting an error of data selected in the first selection step And a modulation step of modulating the coded normal play data and the unencoded trick play data in which the error is corrected to be recorded on a tape.

According to another aspect of the present invention, there is provided a method of reproducing a digital video tape for trick play, the method comprising correcting an error of encoded normal play data and unencoded trick play data reproduced from a tape; Encoding the unencoded trick play data after correction, temporarily storing the normal play data and the trick play data, and selectively supplying the temporarily stored normal and trick play data to an ATV. Characterized in that.

In order to achieve another object of the present invention, a recording apparatus of a digital video tape for trick play according to the present invention comprises the steps of correcting an error of encoded normal play data and unencoded trick play data reproduced from a tape, and the error; Encoding the unencoded trick play data after correction, temporarily storing the normal play data and the trick play data, and selectively supplying the temporarily stored normal and trick play data to an ATV. Characterized in that.

In order to achieve another object of the present invention, a digital video tape reproducing apparatus for trick play according to the present invention includes demodulation means for demodulating the head after reading encoded normal play data and unencoded trick play data reproduced from the tape. First error correction means for receiving an output of the demodulation means and correcting an error using a first error correction sync block, and receiving the output of the first error correction means as the normal play data and the trick play data. Separating means for selectively separating and outputting, Second error correcting means for receiving the normal play data from the separating means and correcting an error using a second error correction sync block, and The unencoded trick from the separating means Encoding means for receiving and encoding play data and the second error correction means. A first storage means for receiving the output, temporarily storing and outputting the output, a second storing means for receiving the output of the encoding means, temporarily storing and outputting the output, and outputting the first and second storage means to the ATV. And selecting means for selecting a signal.

With reference to the accompanying drawings will be described in more detail the present invention.

FIG. 1 shows a track format of a digital video tape having a recording format of an SD-VCR, in which an ATV signal is recorded using the recording space of this track format as it is. That is, normal play data and trick play data of the ATV signal are recorded in the video sector.

In FIG. 1, the track is the sequence of the scanner, i.e., the Insert and Track Information (ITI) sector 200, the audio sector 202, the video sector 204 and the subcode sector 206 from the start of the track at which the head starts scanning. The caps G1, G2, and G3 exist between the sectors. The ITI sector 200 includes a preamble (ITI pre-amble) area 208, a start-sync block area 210, a track information area 212 and a postamble (ITI post amble). ) Area 214. The audio sector 202 has a preamble area 216, fourteen audio data sync blocks 218, and an audio post-amble area 220. The video sector 204 has a preamble region 222, 149 video data sync blocks 224, and a postamble region 226. The subcode sector 206 has a preamble area (Subcode Pre-Amble), a subcode area 230 and a subamble area (Subcode Post Amble) 232. The area after the subcode sector 206 is an overwrite margin 234.

The transport bitstream of the ATV signal is repeated in the order of, for example, I-P-B-B-P-B-B-P-B-B. Where I is an independently coded intra frame, P is a predicted frame coded using motion compensation from a previous intra frame or a predicted frame, and B is a frame of the previous and subsequent intra frames or It means a bidirectional predicated frame coded using motion compensation. The trick play data uses intra frames that can be independently coded among normal data.

FIG. 2 shows the head structure and track scan trajectory of the two head scanner for reproducing the signal recorded on the tape of the SD-VCR of FIG.

In the present invention, as shown in FIG. 3, intra frame data corresponding to the highest double speed, for example, 20 times speed is selected, and the AC coefficient area of each DCT block of the selected intra frame data is divided into a plurality of areas.

The DC coefficient 400 of the DCT block shown in FIG. 3 is commonly used at all speeds such as 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 times, and has an AC coefficient of 1 and 2. The field 402 is used at 4 times speed, contributing to the improvement of image quality at low speed.

4 is a diagram showing the format of tracks on a tape according to the present invention, in which region A represents video regions 606, 608 and 610, and region B represents audio region 612, respectively, and the first region 606 in the video region. ), Normal data is recorded, and trick play data is recorded in the second area 608 and the third area 610 each consisting of 15 sync blocks, which are hatched, and reference numeral 600 denotes 1800 tracks. 602 represents 40 tracks and 604 represents 8 tracks, respectively.

As shown in FIG. 4, the DC value is recorded every 40 tracks 602 to display the DC value of the trick play data at a high speed at a high speed, and to obtain the image of the trick play of the higher resolution as the low speed increases. The low frequency component is recorded every 8 tracks 604.

Various modifications are possible within the spirit and scope that the trick play data is not limited to the data area shown in FIG. 4 but can be set to 30 sync blocks anywhere in the area A. FIG.

Two examples of such a disease form are shown in FIGS. 5A and 5B.

5A and 5B show the structure of a video sector composed of audio sectors and 149 sync blocks of each track on a video tape, the left number ⅰ being the number of sync blocks for pure video data, and reference numerals 804 and 1000. Is the area where normal data is recorded in the data area, 800 and 802, 1002 and 1004 are areas where the trick data is recorded in the data area, 806 and 1006 are internal error areas for error correction, and 808 and 1008 are external codes for error correction. Area. The low frequency component shown in FIG. 4 is recorded in the 21-35 sink blocks 800 of FIG. 5A, the DC component is recorded in the 36-50 sink blocks 802, and the 77-91 sink blocks of FIG. 5B. A low frequency component is recorded at 1000, and a DC component is recorded at 92-106 sink blocks 1004, respectively.

Each sync block is composed of two bytes of sync codes 810 and 1010, three bytes of identification codes 812 and 1012, 77 bytes of data 814 and 1014, and eight bytes of error correction parity 806 and 1006. It is composed.

The first 800 and 1002 and second trick play data areas 802 and 1004 track all scan trajectories at given even speeds, i.e. 2, 4, 6, 8, 10, 14, 16, 18, 20 times. Thus, the pickup of trick play data at a given double speed is set as a common possible area.

The recording of the trick play data is performed by selecting the frame data corresponding to the maximum double speed among the intra frame data to form a plurality of sync blocks using the DC coefficient of each DCT block and the AC coefficients of 1 and 2 and 30 sink blocks for each track. Record by assignment.

In the description of the present invention, for convenience of explanation, as shown in FIG. 5B, the trick data is recorded in 30 sync blocks in the middle portion of the data area.

In the present invention, the trick data is repeatedly recorded and reproduced on the track as much as twice the maximum speed to perform the trick play. It is determined which head is useful according to how the trick data is recorded on the magnetic tape and the possible speed of the trick play. The invention has also been studied in the light of such a scope. Then, it is clarified what effect occurs when the trick data is repeatedly recorded on the track corresponding to twice the maximum speed according to the method of the present invention.

FIG. 6 is a diagram for describing a pattern in which a two-head scanner shown in FIG. 2 scans a digital video tape at a maximum 20x speed of trick play data recorded in the middle of the video area. Denotes the number of the sync block. Although not shown in the drawing, normal play data is recorded in the sync blocks 21-76 and 107-167, and as shown in the figure, low frequency components of the trick play data are included in the sync blocks 77-91. This sync block 92-106 is an embodiment in which the DC component of the trick play data is recorded. In the present invention, the trick data is recorded only in the video data area. However, the present invention will be mentioned in advance even if the trick data is recorded in the audio data area. For convenience of description, the trick data is recorded and described only in the video data area.

First, in the case of 20x speed, the maximum speed is 20x, so the number of tracks to be allocated is 40. The same trick data is recorded in the trick data recording area having the same sync block number in 40 tracks. The white part is the area where the trick data is recorded, and the hatched part is the part that Head A + and Head B- scan and read when performing the trick play, and the other sync blocks, which are not shown in the drawing, are recorded with normal data. Area. Head A + with + Azimuth scans and reads the + part track, and Head B- with Azimuth scans and reads the -part track.

Head A + decodes 78, 79, 81, 82, 84, 85, 87, 88, 90, 91, 93, 94, 97, 100, 103, 104 and 106, and Head B- decodes 77, 80, 83, 86, 89, 92, 95, 96, 98, 99, 101, 102 rule 105 is deciphered.

7 shows an example of a pattern in which a two-head scanner scans a digital video tape when playing 4 and 8 times the speed of trick play data. In the same manner as in the case of 20 times, the head A + is a sync block 82-90 and 102-106 can be deciphered and Head B- can decode sync blocks 77-81 and 91-101. That is, in the case of the maximum 4x speed, the head A + and the head B- are allocated to eight tracks to scan each track for which trick data is recorded from sync blocks 77 to 106, respectively.

At 8x, the maximum speed is 8x, so the number of tracks to allocate is 16, and Head A + decodes sync blocks 79-83, 88-91, 96-99, 105, and 106, and head B- is 77. , 78, 84-87, 92-95 and 100-104 are decoded to scan all areas where the trick data is recorded.

Therefore, in the present invention, when scanning 40 tracks at 20 times speed, the DC components are recorded every 40 tracks so that DC components of the trick play data can be picked up, and as shown in FIG. Since 1 and 2 AC components shown in FIG. 3 are repeatedly recorded for each track, the AC components of the trick play data can be picked up by scanning all 8 tracks, so that a clear picture quality can be obtained at a low even speed. In addition, the present invention can be 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 times the speed to provide a wider choice for the user.

An apparatus for recording normal play data and trick play data on the above-described recording tape will be described with reference to FIG. 8 and FIG.

8 is a block diagram showing an apparatus for recording trick play data on a tape in a digital video tape according to the present invention, and includes a storage unit 1200, a signal processing unit 1202, a first selection unit 1204, and an error correction unit. 1206 and modulator 1208.

The 19.3 Mbps ATV signal input from the ATV through the IN terminal is temporarily stored by extracting only normal play data from the storage unit 1200.

FIG. 9 is a detailed block diagram of the signal processor 1202 of FIG. 8 according to the present invention, and includes a decoder 1400, an inverse quantizer 1402, a second selector 1404, and a quantizer 1406. It is composed of

The function and operation of the signal processor 1202 shown in FIG. 8 will be described in detail with reference to FIG. 9 of the above-described configuration.

The decoder 1400 removes all dummy data of the input ATV signal, that is, removes B and P frames in a group of picture (GOP) structure, which is a substructure of a moving picture structure, and at predetermined intervals. Variable length decoding is adopted using only independently decodable intraframes which are supplied to and contain trick play data, which corresponds to the value immediately after quantization in an ATV. The inverse quantization unit 1402 inputs the decoded intraframe and dequantizes it according to a scaling factor inputted one by one in a slice or macroblock unit according to the structure of the moving image, which corresponds immediately after the DCT block generation step in the ATV. The second selector 1404 receives the output of the inverse quantizer 1402 and selects the DC 400 and the 1 and 2AC coefficients 402 as 8 bits, respectively, of the DCT coefficients shown in FIG. The coefficients are converted to '0' data and output. The quantization unit 1406 receives the selected DCT coefficients and quantizes them with a scaling factor defaulted to a predetermined value, and then outputs the quantized coefficients to the first selection unit 1204.

The output of the storage unit 1200 or the signal processing unit 1202 selected by the first selecting unit 1204 shown in FIG. 8 is the error correcting data of the outer code error correcting unit shown in FIGS. 5A and 5B in the error correcting unit 1206. Error correction coding is performed using the data of 808 and 1008 and the internal code error correction data 806 and 1006. The error correction coded data is modulated by the modulator 1208 and recorded on the tape in the form of quantization coefficients.

10 is a block diagram of a reproducing apparatus for reproducing trick play and normal play data recorded on a digital video tape according to the present invention, and includes a demodulator 1600, a first error correcting unit 1602, and a separation unit 1604. And a second error correction unit 1606, an encoding unit 1608, a first storage unit 1610, a second storage unit 1612, and a selection unit 1614.

A method and apparatus for reproducing trick play data from the above-described recording tape will be described in detail with reference to FIG. 10 through the above-described configuration.

After the head reads the data recorded on the tape and demodulates it in the demodulation unit 1600, the first error correction unit 1602 executes the internal call error correction sink blocks 806 and 1006 shown in Figs. 5A and 5B. The first error correction is used.

Detailed descriptions of the error correction are well-known techniques and thus will be omitted.

After the separation 1604, the error-corrected data is separated by sync into normal play data and all even-speed trick play data. The second error correction unit 1606 corrects the second error by using the outer block error correction sink blocks 808 and 1008 shown in FIGS. 5A and 5B. Since the data transmitted to the ATV through the second selector 1604 should be a variable length coded moving picture structure that can be decoded by the ATV, the trick play data input in the form of quantization coefficients is variable length coded by the encoder 1608. The outputs of the second error correction unit 1606 and the encoder 1608 are input to the first storage unit 1610 and the second storage unit 1612 and temporarily stored, respectively, and then normal play and trick play generated in the ATV. It is selected by the selection unit 1614 controlled by the data selection signal and sent to the ATV.

Therefore, in the present invention, the DC value is recorded every 40 tracks so that at least the DC value can be displayed on the screen when performing trick play at high speed, and the low frequency component is recorded on the tape every 8 tracks, thereby increasing the resolution at low speed. Trick data can be obtained, and the trick play data is encoded and quantized instead of recorded on tape, eliminating the need to record additional information according to the encoding, and error propagation that can be serious due to encoding on the tape. It is effective to prevent in advance.

Claims (9)

ATV signals including frame data supplied at predetermined intervals and independently decodable are divided into normal play data and trick play data to be formatted on a digital video tape, wherein the data area of the video sector of each track of the digital video tape is divided. The first region, the second region, and the third region are divided into the first region, and the normal play data is recorded in the first region, and the second region is selected to correspond to the highest even number N among a plurality of stitch numbers. The DC component of the trick play data, which is the frame data, is repeatedly recorded at 2N track intervals, and in the third region, the AC component of the trick play data is track intervals of multiples of M (MN, an even number of N's divisors). The format of a digital video tape, which is recorded repeatedly. 2. The format of a digital video tape as claimed in claim 1, wherein the trick play data is recorded in a plurality of consecutive sync blocks. 2. The format of a digital video tape as claimed in claim 1, wherein the given highest even times is 20 times. A storage and signal processing step of temporarily storing normal play data in an ATV signal including frame data supplied at predetermined intervals and independently decodable, and processing the trick play data into unencoded data; A first selecting step of selecting the normal play data or trick play data; An error correction step of correcting an error of the data selected in the first selection step; And a modulation step of modulating the coded normal play data with the error corrected in order to record the unplayed trick play data on the tape. The method of claim 4, wherein the storing and signal processing comprises: a storing step of temporarily storing the encoded normal play data; A decoding step of decoding the trick play data of the frame data; An inverse quantization step of inversely quantizing the decoded trick play data according to a scaling factor of a moving picture group; A second selecting step of selecting only direct current and predetermined AC components of the dequantized data; And a quantization step of quantizing the components of the data selected in the second selection step by the scaling factors. Correcting an error between the encoded normal play data reproduced from the tape and the unencoded trick play data; Encoding the unencoded trick play data after the error correction; Temporarily storing the normal play data and the trick flare data; And selectively supplying the temporarily stored normal and trick play data to an ATV. Storage means for temporarily storing and outputting normal play data of the ATV signal including frame data supplied at predetermined intervals and independently decodable; Signal processing means for receiving the frame data and processing the trick play data into unencoded data; First selection means for inputting and selectively outputting the output of said storage means and said signal processing means; Error correction means for receiving an output of the first selection means and correcting an error of the trick play data and the normal play data; And modulating means for correcting errors and modulating the quantized coded normal and signed and unaccepted trickflare data on a tape. 8. The apparatus of claim 7, wherein the signal processing means comprises: decoding means for receiving and decoding the trick play data of the frame data; Inverse quantization means for receiving the decoded data and inverse quantization according to a scaling factor of a moving picture group; Second selection means for receiving the output of the weakening means and selecting only direct current and predetermined AC components of the trick play data; And quantization means for receiving the output of said second selection means and quantizing it with said scaling factor. Demodulation means for demodulating the head after reading the encoded normal play data and the unencoded trick play data reproduced from the tape; First error correction means for receiving an output of the demodulation means and correcting an error using a first error correction sync block; Separating means for receiving the output of the first error correcting means and selectively outputting the normal play data and the trick play data; Second error correction means for receiving the normal play data from the separation means and correcting an error using a second error correction sync block; Encoding means for receiving and encoding the unencoded trick play data from the separating means; First storage means for receiving the output of the second error correction means and temporarily storing and outputting the output; Second storage means for receiving the output of the encoding means and temporarily storing the output; And selecting means for receiving the outputs of the first and second storage means and selecting a signal to be supplied to the ATV.