JP2004088671A - Digital video tape recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the execution of a right error correction even if residual data, which is not erased and remains on a substrate track, is reproduced at an in-point and an out-point when editing a tape, in a case where an error parity data is recorded on the track prior to the in-point and on the track following the out-point. <P>SOLUTION: Upon writing in data on tracks, a flag is added to respective editing units at both ends of an editing section by an editing control means 116. Upon reading out the data, the existence or non-existence of the flag on the tracks is checked by an editing point flag judging means 117 to judge the track to be the editing units at both ends of the editing section, and the track at both ends of the editing section is invalidated. In this process, an error correction is executed correctly even if the residual data, which is not erased and remains on the substrate track, is reproduced at the in-point and the out-point when editing the tape, in the case where the error parity data are recorded on the track prior to the in-point and on the track following the out-point. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a digital VTR (hereinafter referred to as a digital VTR) that performs editing operations on a tape, such as insert and assemble, using a helical scan type recording / reproducing apparatus.
[0002]
[Prior art]
As a device for recording and reproducing moving image signals, a so-called helical scan recording VTR, which mounts a magnetic head on a rotating drum and scans the head obliquely with respect to a tape for recording, is generally used.
[0003]
Hereinafter, recording and reproduction of a conventional digital VTR will be described with reference to the drawings.
The moving image signal to be recorded is composed of a video signal composed of a series of images sampled at a fixed period and an audio signal temporally coincident with the video signal. For example, in the case of the NTSC system, a moving image is formed by a series of images sampled at a 1/30 second cycle. At this time, each image sampled in a 1/30 second cycle is called a frame.
[0004]
At present, in a generally used compression type digital VTR, video data of each frame is compressed to a fixed data amount by digital signal processing, and the compressed data is recorded on a fixed number of helical tracks on a tape. . For example, in the D-7 format of the SMPTE 306M standard, one frame of NTSC video data is recorded on ten helical tracks on a tape.
[0005]
FIG. 6 is a track pattern diagram schematically showing the D-7 format, and shows 10 tracks on which video data and audio data for one frame are recorded.
[0006]
In FIG. 6, each track includes a video sector 601, an audio sector 602, and an audio sector 603. One frame of video data is recorded in the video sector 601, one frame of first channel audio data temporally corresponding to the video data is recorded in the audio sector 602, and one frame of the same frame is recorded in the audio sector 603. The audio data of the second channel is recorded.
[0007]
At this time, it is preferable that the width of one track is as small as possible because the recording density is high and it is economical.
At present, so-called azimuth recording is generally used, in which interference from adjacent tracks is prevented by changing the magnetization direction. As a result, adjacent tracks are recorded without gaps, and the tape is effectively used. In this case, it is ideal that the track width is exactly the same as the effective reproduction track width necessary for obtaining an error rate of a certain level or less during reproduction, because the tape utilization efficiency is the highest.
[0008]
However, when performing so-called insert editing, which rewrites part of the data on the tape once recorded, mechanical errors due to cylinder processing / assembly accuracy, tape expansion / contraction, etc., and helical track follow-up control accuracy Due to the tracking error caused, the rewritten track is recorded with a deviation from the originally recorded track. For this reason, at the start point (hereinafter referred to as “in point”) and the end point (hereinafter referred to as “out point”) of the section in which a new track group is recorded, the originally recorded track is cut by the newly recorded track, It is possible that the width of the remaining tracks will decrease.
[0009]
With reference to FIG. 7, a description will be given of track scraping when a track group overwritten at the in point shifts forward.
FIG. 7 is a track pattern diagram for explaining track scraping at the conventional in-point.
[0010]
In FIG. 7, the first track 702 immediately after the in-point of the upper track group to be overwritten is recorded to be shifted to the last track 701 immediately before the in-point of the previously recorded base track group. Since the overlapped portion is overwritten by the track 702, the width of the track 701 is substantially reduced.
[0011]
Therefore, the conventional VTR is designed so that the width of the remaining track 701 has a width necessary for reproduction even when the maximum deviation determined by the mechanical accuracy occurs. For example, in the D-7 format shown in FIG. 6, the track width at the time of recording is set to 18 μm while the required minimum track width is 9 μm.
[0012]
In the insert editing as described above, track scraping occurs only before and after the IN point and the OUT point. In the case of a digital VTR in which compressed data is arranged in a fixed number of tracks in frame units as described above, editing is performed in frame units due to the nature of video data, so that the in point and the out point are frame units on the tape. It is limited to tracks at both ends of a corresponding fixed number of track groups (hereinafter, referred to as editing units on the tape).
[0013]
Therefore, in order to further increase the use efficiency of the tape, a method of further reducing the track width with respect to the conventional digital VTR as described above has been proposed by the invention described in JP-A-2001-229626. However, in this method, since the track width is reduced to the minimum width required for reproduction, there is a problem that the under-recording track recorded in advance at the IN point and the OUT point may be completely overwritten. . This will be described in detail with reference to FIG.
[0014]
FIG. 8 is a track pattern diagram for explaining track shaving that makes reproduction impossible at the in-point in the related art, and shows this state for the in-point.
In FIG. 8, the last track 801 of the base frame previously recorded is almost entirely overwritten by the first track 802 of the upper frame to be newly overwritten, and the track width required for reproduction remains. Not. In this state, at the time of reproduction, all data recorded on the track 801 becomes an error. Also, since the track 802 has the same azimuth direction as the track 803, the tracks 802 and 803 are reproduced simultaneously, and both the data of the tracks 802 and 803 become errors.
[0015]
As described above, there is a problem that an extremely large number of errors occur. In the above-mentioned conventional example, tracks 801 and 802 at both ends of an edit unit on a tape which can be an in-point and an out-point are provided. In addition, unnecessary data is arranged in normal reproduction, and normal reproduction image data is not arranged. As a result, even if the track 801 is cut off by the insert editing, the normal reproduction image can be reproduced without an error because no valid data is arranged.
[0016]
Further, in the above conventional example, only at the in-point and the out-point, erasing is performed without recording the track 802 at the end of the upper frame, or by recording a signal of a single frequency on the track 802, This prevents the occurrence of an error due to interference from the track 802 in the same azimuth direction during the reproduction of. At this time, data that should be arranged on the track 802 is not recorded, but there is no problem because the normal reproduced image data is not arranged there.
[0017]
In the above conventional example, auxiliary data that is not necessary for normal reproduction, such as a search image, is recorded on a track that may be erased by editing. However, such an auxiliary data such as an audio signal is recorded. When it is not necessary, the error correction capability has been enhanced by recording a part of the error correction parity of the normal reproduction data on a track which may be erased by editing.
[0018]
Also in this case, similarly to the above-described conventional example, only the erasing is performed without recording the track 802 at the upper edge only at the in-point and the out-point, or a single-frequency signal having no problem in reproduction is recorded in the track 803. Is recorded, it is possible to prevent an error from occurring due to interference from the track 802 in the same azimuth direction when the track 803 is reproduced. By this processing, the error-corrected parity data arranged on the tracks 801 and 802 is not reproduced from the track at the time of reproduction, but the non-reproduced parity data is treated as a lost symbol in the error correction operation. Correct error correction can be performed.
[0019]
However, errors occurring at the in-point and the out-point may not only be caused by the above-described track shaving or azimuth disturbance, but also may be caused by the unerased tracks immediately after the under-in point and immediately before the under-point out point. This will be described in detail with reference to FIG.
[0020]
FIG. 9 is a track pattern diagram for explaining the remaining unerased data at the conventional in-point, and shows the problem of the unerased data at the in-point.
In FIG. 9, when the first track 902 of the upper frame to be newly overwritten is shifted backward as shown in FIG. The track 903, which should have been overwritten or erased immediately after the in point of the base, remains without being overwritten. As described above, the track 902 is used only for recording or erasing at a single frequency in order to prevent the same azimuth disturbance when the upper track 902 is shifted forward. It does not cause any interference.
[0021]
[Problems to be solved by the invention]
However, since the tracking deviation at the time of editing occurs in the backward direction as well as in the forward direction, the width of the track 903 remaining to be erased may have a sufficient width for reproduction. Therefore, the data recorded on the track 903 can be read without error. It may be reproduced.
[0022]
At this time, as described above, when a part of the error correction parity is arranged on the tracks 902 and 903 which may be erased by editing, the error correction parity data recorded on the track 903 is changed without error. The data is reproduced and error correction is performed together with the reproduced data of the upper frame. However, since the parity data reproduced from the track 903 is generated from the base data overwritten by the upper frame, the parity data is an error parity that is inconsistent with the data of the upper frame. As a result, error correction is performed using inconsistent parity, and a serious problem that the error correction capability is significantly impaired may occur.
[0023]
In order to solve this problem, the digital VTR according to the present invention, when storing error correction parity in tracks before and after the in-point and out-point, reproduces the unerased portion of the background at the in-point and out-point by tape editing. Even if the error is corrected, the purpose is to correctly correct the error.
[0024]
[Means for Solving the Problems]
In order to achieve the above object, a digital VTR according to claim 1 of the present invention is a helical scan type digital VTR that performs an editing operation on a tape by using a fixed number of tracks corresponding to a frame as an editing unit, Editing means for adding information indicating the in-point to all tracks in the data write start edit unit when writing data, and adding information indicating the out point to all tracks in the write end edit unit; and Means for checking the presence or absence of the information indicating the point and the information indicating the out point to determine whether the track is a write start track or a write end track. The feature is that the track is invalidated.
[0025]
According to a second aspect of the present invention, there is provided a digital VTR of a helical scan type which performs an editing operation on a tape using a fixed number of tracks corresponding to a frame as an editing unit and stores error correction parity in tracks at both ends of the editing unit. Editing means for adding information indicating an in point to all tracks in a data write start edit unit and adding information indicating an out point to all tracks in a write end edit unit when writing data; and reading data. Determining whether or not there is information indicating an in point and information indicating an out point, and determining whether the track is a writing start track or a writing end track. Invalidates the error correction parity of the track.
[0026]
As described above, when the error correction parity is stored in the tracks before and after the IN point and the OUT point, the error can be correctly corrected even if the rest of the background is erased at the IN point and the OUT point in the tape editing.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
In the digital VTR of the present invention, an in-point flag area and an out-point flag area are set for each editing unit recorded on the tape, and a start point (in point) and an end point (out point) of a continuous overwrite recording area at the time of editing. ), The in-point and the out-point can be known at the time of reproduction based on the reproduction data from the in-point flag area and the out-point flag area. Therefore, in the case of the IN point, the error correction parity arranged in the first track of the edit unit in which invalid background data may be reproduced, and in the case of the OUT point, the invalid background data is reproduced. The error correction parity arranged in the last track of the edit unit that may have been lost can be treated as lost regardless of the actual playback state.
[0028]
Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1, 2, 3, 4, and 5. FIG.
FIG. 1 is a block diagram of a digital VTR of the present invention, FIG. 2 is a schematic diagram of a track pattern in the digital VTR of the present invention, FIG. 3 is a data structure diagram of audio error correction data of the present invention, and FIG. FIG. 5 is a data structure diagram for explaining a recording position of an in-point / out-point flag according to the present invention.
[0029]
FIG. 2 shows 12 tracks on which data of one frame is recorded. Each track includes video sectors 201 to 212 for recording video data and audio sectors 213 to 212 for recording audio data of the first channel. 218 or audio sectors 219 to 224 for recording the audio data of the second channel are arranged, respectively. The track pitch is set to 9 μm, which is の of the conventional example shown in FIG. Here, each of the audio sectors 213 to 218 and 219 to 224 in which data of one frame of each audio channel is recorded is an editing unit of audio.
[0030]
As described above, the video data constituting the normal reproduced image is arranged over 10 tracks of the video sectors 202 to 211, and the search image data is arranged in the video sectors 201 and 212 at both ends. In the first audio channel, all audio data and the main part of the outer correction code parity data are arranged in audio sectors 214 to 217, and the remaining part of the outer correction code parity data is arranged in audio sectors 213 and 218. You. In the second audio channel, all audio data and the main part of the outer correction code parity data are arranged in audio sectors 220 to 223, and the remaining part of the outer correction code parity data is arranged in audio sectors 219 and 224.
[0031]
The error correction code in the first audio channel is shown in FIG. 3 for each of three plus azimuth sectors of the audio sectors 213, 215, and 217 and three minus azimuth sectors of the audio sectors 214, 216, and 218. The configuration is as follows.
[0032]
In FIG. 3, one row in the horizontal direction represents one sync block. One sync block is composed of a sync pattern of 2 bytes, ID data of 3 bytes, 154 bytes of audio data or outer correction code parity, 2 bytes of additional ID, and 16 bytes of inner correction code parity.
[0033]
The vertical columns of byte numbers 5 to 158 are 12 bytes of audio data and 12 bytes of outer correction code parity generated from the data, respectively, and constitute an outer correction code.
[0034]
The error correction data structure of FIG. 3 includes 154 bytes × 12 blocks = 77 bytes × 24 blocks of audio data. Since each of the plus azimuth sector and the minus azimuth sector has the error correction data structure of FIG. 3, 77 bytes × 48 blocks of audio data can be recorded for one audio channel.
[0035]
For the following description, the number of the error correction data structure corresponding to the plus azimuth sectors 213, 215, 217 is 0, and the number of the error correction data structure corresponding to the minus azimuth sectors 214, 216, 218 is 1 Each of the sync blocks is assigned an inner block number of 0 to 23 shown in FIG.
[0036]
FIG. 4 shows an arrangement of the sync blocks subjected to the error correction coding as described above in the audio sectors 213 to 218. In FIG. 4, each column indicates a sync block arranged in each audio sector, and two numbers written therein indicate an error correction data structure number and an inner block number. For example, it indicates that the sync block of the inner block number 0 of the error correction data structure number 0 is arranged in the first (lowest) sync block of the audio sector 215.
[0037]
As shown in FIG. 4, for the plus azimuth audio sectors 213, 215, and 217, the sync blocks of the inner block numbers 0 to 11 including the audio data of the error correction data structure number 0 are divided into six blocks, and the audio blocks are divided into six blocks. The sync blocks of inner block numbers 12 to 23 including the outer correction code parity arranged in the sectors 215 and 217 are divided into three blocks and arranged in the audio sectors 215 and 217, and the remaining six blocks including the outer correction code parity are provided. In the audio sector 213.
[0038]
For the audio sectors 214, 216, and 218 of minus azimuth, the sync blocks of the inner block numbers 0 to 11 including the audio data of the error correction data structure number 1 are divided into six blocks and arranged in the audio sectors 214 and 216. Then, the sync blocks of the inner block numbers 12 to 23 including the outer correction code parity are divided into three blocks and arranged in the audio sectors 214 and 216, and the remaining six blocks including the outer correction code parity are arranged in the audio sector 218. I do.
[0039]
By arranging in this manner, blocks including audio data are not arranged in the audio sectors 213 and 218 which may be lost when only the first audio channel is inserted. Can reduce the probability of interpolating audio data.
[0040]
Regarding the data arrangement in the second audio channel, similarly, two error correction data structures are configured and arranged in the audio sectors 219 to 224 in the same manner as the first audio channel. The audio sectors 213, 214, 215, 216, 217, and 218 in the first audio channel correspond to the audio sectors 219, 220, 221, 222, 223, and 224 in the second audio channel, respectively.
[0041]
At this time, of the two bytes (byte numbers 159 and 160) of the additional ID in FIG. 3, the in-point flag and the out-point flag are recorded using two bits of bit 1 and bit 0 of byte number 159. FIG. 5 shows the contents of the byte 159, in which bit 1 records a flag E1 indicating an audio in point and bit 0 records a flag E0 indicating an audio out point.
[0042]
The values recorded in the in-point flag E1 and the out-point flag E0 are determined as follows.
First, in normal recording which is not editing, since all sectors are recorded continuously, the flags E1 and E0 are set to "0" for recording.
[0043]
Next, in the audio sector group (editing unit) for one frame of each audio channel, when the audio sector group is overwritten and recorded, the recording position of the audio sector group on the tape is shifted forward in the tape longitudinal direction. When recording an existing audio sector at the same time, set "0" to the flag E1 of all audio sync blocks included in the audio sector group, and set "1" to the flag E1 when not recording the preceding audio sector at the same time. And record.
[0044]
Finally, in the audio sector group (editing unit) for one frame of each audio channel, when the audio sector group is overwritten and recorded, the recording position of the audio sector group on the tape is rearward in the tape longitudinal direction. When the audio sectors existing in the audio sector group are simultaneously recorded, "0" is set in the flag E0 of all the audio sync blocks included in the audio sector group. When the rear audio sector is not recorded simultaneously, "1" is set in the flag E0. Set and record.
[0045]
For example, in the audio sector arrangement shown in FIG. 2, when only the first audio channel is overwritten and the second audio channel is not overwritten, the front sector is also rearward with respect to the audio sector groups 213 to 218. Sector 219 is also a sector of the second audio channel and is not recorded simultaneously with the audio sector groups 213 to 218. Therefore, the flags E1 and E0 of all the audio sync blocks included in the audio sector groups 213 to 218 are both set to “1”. And record. At this time, the audio sectors 213 and 218 on the tracks at both ends of the editing unit are not actually recorded but are erased or a signal of a single frequency is recorded.
[0046]
Similarly, when only the second audio channel is overwritten, the flags E1 and E0 are both set to "1" for recording, and the audio sectors 219 and 224 are not recorded.
[0047]
For example, in a case where both the first audio channel and the second audio channel are overwritten, an audio sector group including the first audio channel of the first frame of the section to be overwritten is recorded. Since the front audio sector is not recorded outside the overwrite recording section and the rear audio sector is a sector of the second audio channel to be recorded simultaneously, the flag E1 of the audio sync block recorded in this audio sector group is set to "". 1 and E0 is set to "0" and recorded. At this time, the first audio sector is not actually recorded, but is erased or replaced with a signal of a single frequency. Further, for the audio sector group including the second audio channel of the last one frame of the section to be overwritten, the audio sector on the rear side is not recorded outside the overwrite recording section, and the audio sector on the front side is simultaneously recorded. Since this is the sector of the first audio channel to be recorded, the flag E1 of the audio sync block to be recorded in this audio sector group is set to "0" and E0 is set to "1" for recording. At this time, the last audio sector is not actually recorded, but is erased or replaced with a signal of a single frequency. Further, in an intermediate frame other than the first and last frames of the overwrite recording section, all the audio sectors are continuously recorded, so that both the flags E1 and E0 are recorded with "0".
[0048]
The configuration of the digital VTR according to the embodiment of the present invention will be described with reference to FIG.
In FIG. 1, reference numerals 101 and 102 denote A / D converters for A / D-converting the input audio and video signals, 103 denotes a compression means for compressing the video data input from the A / D converter 102, 104 Is an outer encoding unit that divides the compressed video data and audio data into frames and arranges them in an error correction data structure to perform outer correction encoding. 105 denotes an inner correction code for the outer correction encoded data for each sync block. Inner recording means for driving the recording head 107 by the inner-coded data; 107, a recording head for recording data on the magnetic tape 108; 109, a waveform read on the magnetic tape 108; Reproducing head 110 amplifies and binarizes analog reproduced waveform from reproducing head A reproducing amplifier for obtaining reproduced digital data by means of an inner decoding means for correcting reproduced data by an inner error correction code for each sync block; Outer decoding means for performing correction; decompression means 113 for decompressing the outer corrected compressed video data; D / A conversion means 114 and 115 for D / A conversion of audio data and video data, respectively; The editing control unit 117 sends flag data indicating the point and the out point to the inner encoding unit 105. The editing control unit 117 monitors the flag data indicating the in point and the out point read from the reproduced sync block, and It is an edit point flag determining means for determining a point.
[0049]
The input audio signal and video signal are digitized by A / D converters 101 and 102, respectively, to obtain audio data 118 and video data 119 before compression. At this time, the audio signal has two channels, and each channel is processed in parallel.
[0050]
The video data 119 before compression is compressed for each frame by the compression means 103 and compressed, and compressed video data 120 is obtained for each frame. One frame of each audio channel of the audio data 118 and the compressed video data 120 of one frame are input to the outer encoding means 104 and subjected to outer error correction encoding.
[0051]
The outer encoding unit 104 divides one frame of data of each audio channel into halves, and arranges each in the audio data portion of the error correction data structure shown in FIG. Further, an outer correction code parity is obtained from the audio data arranged for each column having the same byte number in FIG. 3, and is arranged in the outer parity part in FIG.
[0052]
The data subjected to the outer correction encoding in this manner is output from the outer correction encoding unit 104 for each row in FIG. 3 and sent to the inner correction encoding unit 105.
[0053]
The inner correction encoding unit 105 adds a sync pattern, ID data, and additional ID data to the block composed of the transmitted audio data or outer parity data as shown in FIG. Further, an inner correction code parity is obtained based on the ID data, audio data or outer parity data, and additional ID data, and this is added to the inner parity portion of FIG.
[0054]
At this time, the editing control means 116 generates the values of the audio editing point flags E1 and E0 as described above in accordance with the recording mode, and outputs them as the audio editing point flag signal 121. The inner correction encoding means 105 inserts this into the position of the additional ID shown in FIG.
[0055]
The data 122 configured in the sync block as described above is recorded on the magnetic tape 108 through the recording amplifier 106 and the recording head 107.
As described above, the audio editing point flags E1 and E0 according to the state of the insert recording are recorded in each sync block.
[0056]
When reproducing the tape 108 on which the insert recording has been performed as described above, first, the recording waveform is read by the reproducing head 109, and the reproduced digital data 123 is obtained by the reproducing amplifier 110.
[0057]
The inner decoding unit 111 detects the sync pattern from the reproduced digital data 123 to reproduce the data arrangement in the sync block, and according to the inner correction code parity included in each sync block, ID data, audio data or The reproduction error included in the outer parity data and the additional ID data is corrected. Data 124 including the corrected ID data, audio data or outer parity data, and additional ID data is sent to the outer decoding unit 112.
[0058]
The outer decoding means 112 has a memory constituting the error correction data structure shown in FIG. 3, finds a row address for writing data in accordance with the corrected ID data, and outputs the corrected audio data or outer data to the row. Write parity data and additional ID data. When the reproduction of one frame of data is completed, all the corrected data of the sync block has been written into the memory. At this time, a flag indicating the fact is set for each sync block in the data of the sync block that could not be corrected due to the error in reproduction and the data of the sync block in which the sync pattern could not be detected due to the error in reproduction. . By referring to this flag, the outer encoding unit 112 treats the data of the sync block in which the flag is set as invalid, and treats the data as an erasure in the error correction code theory.
[0059]
At this time, the edit point flag determination means 117 reads the additional ID data 125 for each sync from the memory of the outer decoding means, and performs majority processing on the audio edit point flags E1 and E0 included in the additional ID data 125 for each outer correction code. Then, the continuity between the previous and next sectors at the time of recording of the frame is determined, and the determination result is returned to the outer decoding means 112 as a control signal 126.
[0060]
For example, when decoding the outer codes of the sectors 213, 215, and 217 on the plus azimuth side of the first audio channel, the 18 sync blocks included in the audio sectors 215 and 217 can be subjected to the inner correction and the erase flag If the additional ID data of the non-standing sync block is read out and the number of blocks in which the E1 flag of the additional ID is “1” is a large number exceeding a certain threshold, the audio sector immediately before the audio sector 213 is detected. Determines that the frame was not rewritten at the time of recording, and sends a control signal 126 to the outer decoding means 112 indicating that the frame is an in point. Upon receiving the control signal 126 indicating that the frame is the IN point, the outer decoding means 112 forcibly replaces the sync blocks of the inner block numbers 18 to 23 arranged in the audio sector 213 regardless of the playback state. Treat as vanishing.
[0061]
When decoding the outer codes of the sectors 214, 216, and 218 on the minus azimuth side of the first audio channel, the 18 sync blocks included in the audio sectors 214 and 216 can be subjected to the inner correction and the erasure flag is deleted. The additional ID data of the non-standing sync block is read out, and if the number of blocks in which the E0 flag of the additional ID is “1” is a large number exceeding a certain threshold, the audio sector immediately after the audio sector 218 is output. Determines that the frame has not been rewritten at the time of recording, and sends a control signal 126 to the outer decoding means 112 indicating that the frame is an out point. Upon receiving the control signal 126 indicating that the frame is the out point, the outer decoding means 112 forcibly replaces the sync blocks of the inner block numbers 18 to 23 arranged in the audio sector 218 irrespective of the playback state. Treat as vanishing.
[0062]
By performing erasure correction based on the error correction code theory for these erasures, the outer correction code is decoded.
The outer corrected audio data 127 is converted into an analog signal by the D / A converter 114 to obtain an audio output.
[0063]
The compressed video data corrected by the outer decoding unit 112 is decompressed by the decompression unit 113, and the obtained video data is converted into an analog signal by the D / A converter 115, and a video output is obtained.
[0064]
As described above, when the error parities are stored in the tracks before and after the IN point and the OUT point, the error correction can be performed correctly even if the rest of the background is erased at the IN point and the OUT point in the tape editing.
[0065]
【The invention's effect】
As described above, in the digital VTR of the present invention, the flag is added to the editing unit located at both ends of the editing section by the editing control means at the time of writing data, and the presence or absence of the flag is confirmed by the editing point flag determining means at the time of reading data. When the error parity is stored in the tracks before and after the IN point and OUT point by invalidating the tracks at both ends of the edit section by determining that the edit unit is the edit unit at both ends of the edit section, Even if the erased portion of the background is reproduced at the point and the out point, error correction can be performed correctly.
[Brief description of the drawings]
FIG. 1 is a block diagram of a digital VTR of the present invention.
FIG. 2 is a schematic diagram of a track pattern in the digital VTR of the present invention.
FIG. 3 is a data structure diagram of audio error correction data of the present invention.
FIG. 4 is a track pattern diagram showing sync blocks arranged in an audio sector according to the present invention;
FIG. 5 is a data structure diagram illustrating a recording position of an in-point / out-point flag according to the present invention.
FIG. 6 is a track pattern diagram schematically showing a D-7 format.
FIG. 7 is a track pattern diagram for explaining track scraping at a conventional in point.
FIG. 8 is a track pattern diagram for explaining track shaving in which reproduction cannot be performed at a conventional in point.
FIG. 9 is a track pattern diagram for explaining a remaining unerased part at a conventional in point.
[Explanation of symbols]
101 A / D converter
102 A / D converter
103 Compression means
104 outer coding means
105 inner coding means
106 Recording amplifier
107 storage head
108 magnetic tape
109 Playhead
110 playback amplifier
111 inner composite means
112 Outer composite means
113 Extension means
114 D / A conversion means
115 D / A conversion means
116 Edit control means
117 Edit point flag determination means
118 audio data
119 Video data
120 compressed video data
121 Audio edit point flag signal
122 data
123 Reproduced digital data
124 data
125 Additional ID data
126 control signal
127 audio data
201 Video Sector
202 Video Sector
203 Video Sector
204 Video Sector
205 Video Sector
206 Video Sector
207 Video Sector
208 video sectors
209 Video Sector
210 Video Sector
211 Video Sector
212 Video Sector
213 Audio Sector
214 audio sectors
215 Audio Sector
216 Audio Sector
217 Audio Sector
218 Audio Sector
219 Audio Sector
220 audio sectors
221 Audio Sector
222 audio sectors
223 Audio Sector
224 audio sector
601 video sector
602 audio sector
603 audio sector
701 truck
702 truck
801 truck
802 truck
803 truck
901 truck
902 truck
903 truck

Claims (2)

A helical scan type digital VTR that performs editing work on a tape by using a fixed number of track groups corresponding to frames as an editing unit,
Editing means for adding information indicating an in-point to all tracks in a data write start edit unit when writing data, and adding information indicating an out point to all tracks in a write end edit unit,
Means for determining whether there is information indicating an in point and information indicating an out point when reading data, and determining whether the track is a write start track or a write end track. A digital VTR wherein the track is invalidated. A helical scan digital VTR that performs an editing operation on a tape using a fixed number of tracks corresponding to a frame as an editing unit and stores error correction parity in tracks at both ends of the editing unit,
Editing means for adding information indicating an in-point to all tracks in a data write start edit unit when writing data, and adding information indicating an out point to all tracks in a write end edit unit,
Means for determining whether there is information indicating an in point and information indicating an out point when reading data, and determining whether the track is a write start track or a write end track. A digital VTR wherein the error correction parity of the track is invalidated.

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