|Publication number||USRE41611 E1|
|Application number||US 11/798,311|
|Publication date||31 Aug 2010|
|Filing date||11 May 2007|
|Priority date||16 Apr 1993|
|Also published as||DE69434456D1, DE69434456T2, DE69435252D1, EP0620683A2, EP0620683A3, EP0620683B1, EP1298924A2, EP1298924A3, EP1298924B1, EP2131582A1, EP2131582B1, US5587789, USRE38868, USRE41042, USRE41125, USRE41820, USRE41971, USRE42679, USRE42795|
|Publication number||11798311, 798311, US RE41611 E1, US RE41611E1, US-E1-RE41611, USRE41611 E1, USRE41611E1|
|Inventors||Je Hyung Lee, Soo Kyung Kim, Sang Joon Woo, Tae Seok Yang|
|Original Assignee||Lg Electronics Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (53), Non-Patent Citations (2), Classifications (63)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present application is a continuation application of co-pending Reissue application Ser. No. 11/344,605 filed on Feb. 1, 2006, which is a continuation application of co-pending Reissue Application Ser. No. 10/883,196 filed Jul. 1, 2004, which is a continuation application of Reissue Pat. Re 38,868 (application Ser. No. 09/118,824 ) issued Nov. 8, 2005, which is a Reissue of U.S. Pat. No. 5,587,789 issued on Dec. 24, 1996, for which priority is claimed under 35 U.S.C. §120. The present application also claims priority of Application No. 6441/1993 filed in Republic of Korea on Apr. 16, 1993 under 35 U.S.C. §119. The entire contents of all are hereby incorporated by reference. Note: More than one reissue application has been filed for the reissue of U.S. Pat. No. 5,587,789. The reissue applications are application Ser. Nos. 09/118/824; 10/883,196; 11/344,605; 11/806,513; 11/902,928; 11/798,311; 12/411,333; 12/411,339.
1. Field of the Invention
The present invention relates to a circuit device and method for controlling recording and reproduction in a digital cassette tape recorder, and to an apparatus and method for recording or reproducing digital data to or from a digital storage medium using speed information.
2. Description of the Background Art
For analog/digital conversion for converting an analog video signal into a digital video signal and linear quantization, a signal transmission rate of about 100 Mega bits per second is typically required in the case of a normal TV broadcast signal such as NTSC, SECAM and PAL signals. On the other hand, a high definition TV (HDTV) signal with higher resolution than that of the normal TV broadcast signal requires a signal transmission rate higher than 100 Mega bits.
For achieving data transmission in a limited transmission band, digitized video signals should be transmitted in the form compressed in accordance with the video data compression-technique. In the case of digital cassette tape recorders (digital VCRs) having a limitation on record bandwidth, signals recorded on a magnetic tape may be digital normal TV signals having the form of compressed signals or digital HDTV signals having the form of compressed signals.
Now, operations of the conventional circuits will be described in conjunction with
First, in a recording mode, a compressed HDTV signal or compressed normal TV signal is applied to the interface 1 which, in turn, converts the received signal into a signal V1 capable of being recorded and reproduced. The signal V1 is then inverted into a predetermined form to reduce burst errors in the interleaving and channel-driving circuit 2 which, in turn, outputs signals V2 and V3 channel-divided so as to be matched with the bandwidth of the recording channel.
The outputs V2 and V3 from the interleaving and channel-dividing circuit 2 are applied to the recording formatters 3A and 3B and then added with synchronous signals SYNC, identification signals ID and redundancy bits for error correction codes ECC in the recording formatters 3A and 3B. Resultant signals from the recording formatters 3A and 3B are then received in the channel modulators 4A and 4B which, in turn, output signals V6 and V7 matched with a predetermined recording format, respectively. The outputs V6 and V7 from the channel modulators 4A and 4B are applied to the recording amplifiers 5A and 5B which, in turn, amplify them, respectively.
Outputs V8 and V9 from the recording amplifiers 5A and 5B are applied to selected heads HD1 (or HD3) and HD2 (or HD4) via the switches SW1 and SW2 switched by the output SWP from the drum pulse generator 7, so that they are recorded on a magnetic tape recording medium in a recording format shown in FIG 3.
In this case, the drum pulse generator 7 generates two pulses at every rotation of the head drum 6 driven by the drum motor M1.
Meanwhile, frames have a mixed form of intra-frames (I-frames) able to be independently decoded and predictive frames (P-frames) compressed by moving information of previous screen and unable to be independently decoded, in accordance with a video compression system for HDTV signals or an MPEG (Moving Picture Experts Group) system. Bit rate generated in each frame is non-uniform, as shown in FIG. 5.
In a reproduction mode, the magnetic tape travels by the rotation of the capstan 9 caused by the capstan motor M2 while being in contact with the head drum 6 rotating by the driving force of the drum motor M1. At this time, the heads HD1 (or HD3) and HD2 (or HD4) detect signals on the magnetic tape and send them to the reproduction amplifiers 11A and 11B via the switches SW3 and SW4 switched by the output SWP of the drum pulse generator 7, respectively.
The signals received in the reproduction amplifiers 11A and 11B are amplified to a predetermined level and then sent to the equalizers 12A and 12B which, in turn, output signals V12 and V13 having compensated frequency characteristics, respectively. The signals V12 and V13 from the equalizers 12A and 12B are then applied to the channel demodulators 13A and 13B, respectively, so as to be demodulated. Outputs V14 and V15 from the channel demodulators 13A and 13B are received in the sync-detecting and error-correcting circuits 14A and 14B which, in turn, detect respectively synchronous signals SYNC and identification signals ID from synchronous block of the received signals and remove error components included in the data.
Outputs V16 and V17 from the sync-detecting and error-correcting circuits 14A and 14B are applied to the deinterleaving circuit 15A and 15B which, in turn, deinterleave the signals V16 and V17 and thereby generate signals V18 and V19 having the original signal forms, respectively. The signals V18 and V19 are received in the deformatter 16 and thereby converted to the format having the signal form prior to recording. Signal V20 from the deformatter 16 is applied to the interface 17 which, in turn, generates a reproduced digital signal Vo.
In a speed-varied reproduction, the rotation speed of the head drum 6 is kept constant while the travel of the magnetic tape is accelerated. As a result, the heads HD1 to HD4 travel across tracks on the magnetic tape. The trace of the heads is shown in FIG. 3. Consequently, the detected signals have a discontinuous data form, data burst with a magnitude inversely proportional to the travel speed of the magnetic tape.
In the case of existing analog VCRs video recorders, data of one field are recorded in one track in the reproduction order. Accordingly, regions on tracks from which data are detected in the speed-varied reproduction mode are directly associated with reproduction regions of a corresponding screen. Therefore, video reproduction in the speed-varied mode is possible even when a noise bar is generated due to data detected on an adjacent track.
In the case of existing digital VCRs video recorders, however, data of one field are recorded in a plurality of tracks, as shown in FIG. 3. As a result, reproduction bursts on adjacent tracks have no relation with the reproduction order. In this case, therefore, a frame memory and an addressing process for rearranging data detected are needed. Furthermore, there is a problem of an inevitable mosaic-shaped distortion of small segments due to discontinuous detection of data bursts.
For a video reproduction in the existing digital VCRs video recorders, data bursts detected should be independently decoded. However, these data bursts include unrecoverable other data on the screen or unrecoverable previous screen data, because the data bursts have the digital form compressed using the correlation between signals that may be the important factor of adversely affecting the picture quality in reproduction. The unrecoverable data can not be decoded and thereby reproduced in the form of videos. In particular Further, such a problem becomes more frequent in the case of data obtained from the a video compression systemsuch as the , for example, variable length coding involving non-uniform data lengths.
In other wordsMoreover, although data bursts detected from tracks on which data for the 0-th I-frame, the n-th I-frame, the 2n-th I-frame . . . are recorded can be constructed to a video, data bursts detected from tracks on which data of P-frames are recorded can not be constructed to a video.
Therefore, an object of the invention is to provide an apparatus and method for controlling recording and reproduction in a digital VCR video recorder capable of, in a recording mode, extracting independently-decodable data, namely, intra-frames from digital signals having a compressed form so as to record them on tracks designated with respect to a number of different tape speeds and, in a speed-varied reproduction mode, repeatedly performing a normal-speed travel and a high-speed travel of a magnetic tape digital recording medium so as to detect specific data for speed-varied reproduction periodically or non-periodically recorded on tracks of the magnetic tape, thereby reproducing videos with improved picture quality.
Another object of the invention is to provide an apparatus and method for controlling recording and reproduction of digital data, which address the above noted limitations and other limitations associated with the related art.
Another object of the invention is to provide an apparatus and method for recording and reproducing digital data to and from a digital storage medium in an effective manner.
In accordance with an embodiment of the present invention, this object can be accomplished by providing there is provided an apparatus for controlling recording and reproduction in a digital video cassette tape recorder comprising: a frame extracting means unit for buffering and amplifying compressed digital data input, and extracting specific data for a speed-varied reproduction from the compressed digital data; a frame recording position controlling means unit for calculating the number of tracks for the compressed digital data, selectively outputting a buffered and amplified output and the extracted specific data from said the frame extracting means unit, and outputting a multiplexing timing signal; a frame position information recording means unit for recording position information of tracks for a speed-varied reproduction and index information on a magnetic tape recording medium, based on the multiplexing timing signal; a digital recording means for recording the digital signals including the index information on the magnetic tape recording medium; a digital reproduction means for reproducing the digital signals recorded on the magnetic tape recording medium; a frame position information detecting means unit for detecting position information of specific tracks for the speed-varied reproduction and an index information tape speed controlling means unit for controlling the speed of a capstan motor, based on the detected index information and position information of the specific tracks; and a frame removing means for receiving therein the output from the digital reproduction means unit and removing unnecessary bit streams from the specific data.
In accordance with another embodiment of the invention, there is provided a method for processing a digital signal stored on a digital storage medium, comprising receiving digital data processed to prevent at least one of buffer underflow and buffer overflow and stuffed by stuffing data capable of being detected and removed, the digital data including video data in a first data format converted from video data in a second data format; determining whether a speed-varied reproduction mode is selected for reproduction of the video data in the first data format in a varied speed, the video data in the first data format compressed as at least one of I-frame and P-frame; and reproducing the video data in the first data format in a varied speed based on speed information when the speed-varied reproduction mode is selected, the speed-varied reproduction mode being associated with the speed information, wherein the video data in the first data format is reproduced in the varied speed by processing the video data in the second data format. Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
These and other objects, features and advantages of the invention will become more apparent upon a reading of the following detailed specification and drawings which are given by way of illustration only, and thus are not limitative of the present invention, in which:
In similar to the conventional case, the digital recording unit 18 includes an interleaving and channel-dividing circuit 2, recording formatters 3A and 3B, channel modulators 4A and 4B, recording amplifiers 5A and 5B, a head drum 6 equipped with heads HD1 to HD4, a drum pulse generator 7 and switches SW1 and SW2. With this construction, the digital recording unit 18 records digital signals including index signals on the magnetic tape. For simplicity of the description, the description concerning the digital recording unit 18 will be omitted.
The frame extracting unit 20 includes a buffer 22 adapted to buffer the output signal V1 of the interface 1 and thereby amplify it to a predetermined level, a frame detector 24 adapted to detect specific data corresponding to an intraframe, and a frame memory 23 adapted to store the detected specific data.
The frame recording position controlling unit 21 includes a track number calculator 28 adapted to calculate the number of tracks, a multiplexing timing generator 27 adapted to operate an output SWP of the drum pulse generator 7 and thereby generate a multiplexing timing signal V27, a bit stuffing circuit adapted to make the output signal V23 of the frame memory 23 have a constant data length when the output signal V23 is at an underflow state, and a multiplexer 25 adapted to multiplex the output signals V22 and V23 of the frame extracting unit 20 and thereby output a signal V25.
On the other hand, the frame position information recording unit 19 includes a frame position recorder 29 adapted to receive the multiplexing timing signal V27′ from the frame recording position controlling unit 21 and record, on the leading portion of a track for varied speed, position information of a next track for speed change, and an index signal recorder 30 adapted to record index information of a track to be scanned by an index head 31.
The digital reproduction unit 32 includes the head drum 6 equipped with the heads HD1 to HD4, the drum pulse generator 7, switches SW3 and SW4, reproduction amplifiers 11A and 11B, equalizers 12A and 12B, channel demodulators 13A and 13B, and sync-detecting and error-correcting circuit 14A and 14B. This construction of the digital reproduction unit 32 is similar to that of the conventional digital reproduction unit shown in FIG. 2. Therefore, the detailed description concerning the digital reproduction unit 32 will be omitted for simplicity of the description.
The frame position information detecting unit 33 includes an index signal detector 36 adapted to detect index information from the storage medium, a recording position-synchronized block detector 40 adapted to detect, from the outputs V16 and V17 of the sync-detecting and error-correcting units 14A and 14B, position information of a specific track including specific data recorded, and a recording position decoder 39 adapted to decode the detected position information.
The tape speed controlling unit 34 includes a capstan servo-speed calculating circuit 38 adapted to operate outputs V36 and V39 of the frame position frame detecting unit 33, and a drive signal generator 37 adapted to generate a drive signal V37 for controlling the speed of the capstan motor M2.
Finally, the frame removing unit 35 includes a frame removal timing generator 41 adapted to operate an output of the drum pulse generator 7 and outputs V36 and V39′ of the frame position information detecting unit 33 and thereby generate a timing signal for removing specific data for speed-varied reproduction, a stuffing bit-detecting and removing circuit 42 adapted to detect and remove a stuffing bit adapted for preventing generation of the underflow of the frame memory 23, and a deformatter 16 adapted to convert an output of the digital reproduction unit 32 to the format having the signal from prior to recording.
Operations of the apparatus for controlling recording and reproduction in the a recording/reproducing device, for example, a digital VCR in accordance with an embodiment of the present invention will be described, in conjunction with
First, in a recording mode, an input signal Vi such as a compressed HDTV signal or compressed normal TV signal is applied to the interface 1 which, in turn, converts the received signal into a signal V1 having the form capable of being recorded and reproduced.
The signal V1 from the interface 1 is then applied to the frame extracting unit 20. In the frame extracting unit 20, the received signal V1 is buffered and amplified by the buffer 22. By the buffering and amplifying operations, the signal V1 is delayed for a predetermined time. The frame detector 24 detects compressed I-frames repeated at intervals of n frames, from a bit stream encoded to have frames with different compressed bit lengths. The frame memory 23 stores data of the detected I-frames.
In other words, compressed digital data of the I-frames repeatedly present at intervals of n frames are separated from the encoded bit stream shown in FIG. 4 and then duplicatively recorded on a specific track because they can be independently decoded. A write enable signal W/E of high level is applied to the frame memory 23 only for the period of detecting I-frames from the encoded bit stream by the frame detector 24. As a result, the frame memory 22 can store only the compressed video data of the I-frames.
This procedure for detecting I-frames will be described in detail, in conjunction with FIG. 12. An input bit stream is received in the frame detector 24 and then decoded. The frame detector 24 detects a frame mark code from a header of each frame in the bit stream. When the frame mark code is detected, an increment in frame counted value is carried out. If I-frames are present at intervals of n frames, it is determined whether the number of counted frames equals a multiple of n (i.e., k*n, where k=0, 1, 2, . . . ). When the (n*k)th is detected, a write enable signal W/E of high level is applied to the frame memory 23, thereby enabling compressed digital data bits of a corresponding I-frame to be stored. When a next frame mark code is detected, a write enable signal W/O of low level is applied to the frame memory 23. As a result, it is possible to prevent frames of the frame bit stream other than I-frames from being stored.
The frame recording position controlling unit 21 sends selectively I-frame data V23 and record data V22 outputted from the frame extracting unit 20 to the digital recording unit 18 at a predetermined timing. Accordingly, a recording format shown in
On the other hand, since the lengths of compressed data of frames are non-uniform, the frame memory 23 may encounter at underflow phenomenon that data stored in the frame memory 23 at the moment an I-frame is recorded in the frame memory 23 is insufficient or an overflow phenomenon that data stored in the frame memory 23 prior to recording of an I-frame is full.
This will be described in detail. Assuming that the average bit rate of input data received in the interface 1 is R and the size of regions of the input data occupied by I-frames is α, the average bit rate of data to be recorded is expressed by R+αR. This average bit rate of data is calculated in the track number calculator 28. In this case, α can be calculated from α=the number of tracks i for I-frames/ the number of tracks j for P-frames. Here, the number of tracks, i, is generally determined by the average bit rate of I-frames.
The multiplexing timing generator 27 operates an output V28 of the track number calculator 28 which calculates the number of I-frame tracks, i, and the number of P-frame tracks, j. The multiplexing timing generator 27 also operates the output SWP of the drum pulse generator 7. By these operations, a reference pulse is calculated. One pulse of the output SWP of the drum pulse generator 7 corresponds to a recording period for one track in a case of recording one-channel data and to a recording period for two tracks in a case of recording two-channel data. Accordingly, the multiplexing timing generator 27 outputs a switching signal V27 enabling the multiplexer 25 to selectively output data V23 for double speed stored in the frame memory 23 and normally-recorded data (
In the output V22 from the buffer 22 shown in
In the frame position information recording unit 19, the frame position recorder 29 and the index signal recorder 30 receive the output V27′ from the multiplexing timing signal generator 27 of the frame recording position controlling unit 21. The frame position recorder 29 outputs information V29 based on its frame position discrimination to the recording formatters 3A and 3B. Based on the information V29, the recording formatters 3A and 3B from a synchronous block including information indicative of the position of a track including a next I-frame recorded, in each video data region. The recording formatters 3A and 3B also record the recording position information in the first synchronous block recording position of the tracks including I-frames recorded, as shown in FIG. 9. Here, the recording position information represents the code converted from the number of tracks present between the track including the current I-frame recorded and the track including the next I-frame recorded, as shown in FIG. 11.
On the other hand, the index signal recorder 30 outputs index information V30, namely, a pulse indicative of whether an I-frame has been recorded or not, to the index head 31 which, in turn, records the index information V30 on a control track.
The above-mentioned overall operations will be described in detail. As the head drum 6 carrying the heads HD1 to HD4 is rotated by the driving force of the drum motor M1 while the magnetic tape engaged between the capstan 9 and the pinch roller 10 is fed by the driving force of the capstan motor M2, the interface 1 receiving the input signal Vi such as the compressed HDTV signal or the normal TV signal applies its output V1 to the frame extracting unit 20. Thereafter, the recorded data is buffered and amplified in the buffer 22 for a predetermined period while the I-frame data is stored in the frame memory 23 in accordance with the write enable signal W/E from the frame detector 24.
Subsequently, the multiplexer 25 receives selectively the output V22 from the buffer 22 and the output V23 from the frame memory 23, based on the output V27 from the multiplexing timing generator 27. As a result, the multiplexer 25 outputs the output signal V25 as shown in FIG. 10D to the digital recording unit 18. Thereafter, the interleaving and channel-dividing circuit 2 of the digital recording unit 18 interleaves the signal V25 to a predetermined form for reducing burst errors and then outputs signals V2 and V3 channel-divided to be matched with a recording channel bandwidth to the recording formatters 3A and 3B, respectively.
Accordingly, the recording formatters 3A and 3B form synchronous blocks shown in
Outputs V4 and V5 are converted to a predetermined recording format in the channel modulators 4A and 4B, amplified to a predetermined level by the recording amplifiers 5A and 5B, and then selectively sent to the heads HD1 (or HD3) and HD2 (or HD4) via the switches SW1 and SW2 switched by the output SWP of the drum pulse generator 7 generated by the rotation of the drum motor M1.
Thus, the outputs of the recording amplifiers 5A and 5B selectively applied to the heads HD1 (or HD3) and HD2 (or HD4) via the switches SW1 and SW2 being switched are recorded on the storage medium, for example, a magnetic tape in a recording format shown in FIG. 9.
On the other hand, when a speed-varied reproduction mode is selected in a case where the data of the recording format shown in
The signals detected b the heads HD1 (or HD3) and HD2 (or HD4) are sent to the reproduction amplifiers 11A and 11B via the switches SW2 and SW4 switched by the output SWP of the drum pulse generator 7, respectively. The signals received in the reproduction amplifiers 11A and 11B are amplified to a predetermined level and then sent to the equalizers 12A and 12B which, in turn, compensate distortions of frequency characteristics of the amplified signals V10 and V11, respectively. Resultant signals V12 and V13 from the equalizers 12A and 12B are then applied to the channel demodulators 13A and 13B which, in turn, demodulate the output signals V12 and V13 to the original signal forms, respectively.
Output signals V14 and V15 from the channel demodulators 13A and 13B are received in the sync-detecting and error-correcting circuits 14A and 14B which, in turn, detect respectively synchronous signals SYNC and identification signals ID from the received signals V14 and V15 and remove error components included in the recorded data. Resultant signals V16 and V17 from the sync-detecting and error-correcting circuits 14A and 14B are applied to the deinterleaving circuit 15A and 15B which, in turn, deinterleave the signals V16 and V17 to the original signal forms, respectively. Resultant signals V18 and V19 are then sent to the deformatters 16 of the frame removing unit 35.
At this time, the frame position information detecting unit 33 detects index information recorded on a control track disposed at the lower edge of the magnetic tape by the index head 31. The index information is a pulse indicative of a track including an I-frame. On the other hand, the recording position-synchronized block detector 40 detects recording position-synchronized blocks recorded with I-frames from the outputs V16 and V17 of the sync-detecting and error-correcting circuits 14A and 14B. Upon detecting the index information in order to achieve a discrimination for the position of a specific track, the index signal detector 36 takes into consideration the time taken to control a speed matched with a speed multiple and calculated in the capstan servo speed calculator 38 of the tape speed controlling unit 34. The physical position of the index head 31 is determined by the processing speed of the capstan servo speed calculator 38.
The recording position-synchronized block detector 40 also detects the outputs V16 and V17 of the sync-detecting and error-correcting circuits 14A and 14B and separates recording position-synchronized blocks shown in
Accordingly, the frame position information detecting unit 33 detects specific track position information periodically or non-periodically recorded and track position information about I-frames recorded in the recording position-synchronized blocks, taking into consideration the calculation time taken to control the sped of the capstan motor M2 and the driving time. In this connection, the capstan servo speed calculator 38 receives the position information V36 from the index signal detector 36 and the position information V39 from the recording position decoder 39 and thereby calculates the rotation speed of the capstan motor M2 in accordance with the input speed multiple n. Resultant signal V38 from the capstan servo speed calculator 38 is then applied to the capstan servo driving signal generator 37 which, in turn, controls the speed of the capstan motor M2 so that the capstan motor M2 can be driven repeatedly at a normal speed and a high speed. As a result, the heads HD1 to HD4 mounted on the drum 6 repeatedly travel at the normal speed on specific tracks of the magnetic tape and jump travel on other tracks, thereby enabling reproduction of speed-varied videos.
The outputs V18 and V19 from the digital reproduction unit 32 resulted from the speed-varied reproduction are sent to the deformatter 16 of the frame removing unit 35, converted into the signal form prior to the recording, and then outputted as a speed-varied reproduced signal Vo such as a digital HDTV signal or a normal TV signal via the interface 17.
For the signal conversion in the deformatter 16, it is required to remove the stuffing bits or dummy bits added for preventing the underflow phenomenon of the frame memory 23 upon recording data for varied speed on specific tracks. To this end, the stuffing bit-detecting and removing circuit 42 supplies a bit removing signal V42 for preventing any bit string from being outputted to the interface 17 when a stuffing synchronous code recorded at the starting portion of stuffing bits is detected. The supplying of the bit removing signal V42 is continued until a stuffing bit end code is detected.
In the reproduction at the normal speed, the frame removing unit 35 also separates date of recording tracks for varied speed so that the I-frame data recorded on the magnetic tape for the speed-varied reproduction is prevented from being outputted to the interface 17 and thereby being included in the reproduction signal Vo.
On the other hand, the frame removal timing generator 41 receives position information of tracks recorded with specific data for varied speed from both the recording position decoder 39 and the index signal detector 36 of the frame position information detecting unit 33. Based on the output SWP of the drum pulse generator 7 shown in
Based on the frame removing signal V41, the deformatter 16 removes I-frame data from the signals V18 and V19 (
As apparent from the above description, the present invention provides an apparatus for controlling recording and reproduction in a magnetic VCR capable of separating specific data for a speed-varied reproduction from compressed digital video signals and recording them on designated tracks in a recording mode, recording position information of the designated tracks on a control track by an index head or recording position information of recording position-synchronized blocks at the starting positions of the designated tracks recorded with the specific data so as to accurately scan the designated tracks in a reproduction mode, controlling a capstan servo speed so as to maintain the travel of a magnetic tape at a normal speed and periodically or non-periodically accelerate or decelerate it where specific data for varied-speed have been recorded periodically or non-periodically on predetermined portions of tracks, thereby making heads travel repeatedly at the normal speed and the high speed and thereby detect continuously the specific tracks for varied-speed. In accordance with the apparatus, the specific data for a speed-varied reproduction is removed in the reproduction at the normal speed. Thus, the reproduction at the normal speed can be accomplished.
Therefore, the embodiments of the present invention provide an apparatus and method for controlling recording and reproduction of digital data to and from a digital storage medium, which allow a speed-varied reproduction of the digital data in an effective manner using one or more of various information, for example, multiplexing timing information, synchronization information, varied speed information, index information, frame position information, etc.
Accordingly, the present invention provides a repeatability of reproduced video at a varied speed without any deterioration in picture quality in that it enables recording of specific data for speed-varied reproduction on a digital storage medium in an effective manner and continuous detection of the specific data in the speed-varied reproduction from the digital storage medium.
Although the preferred embodiments of the invention have been disclosed for illustration purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. For example, the teachings of the present invention are equally applicable to other suitable digital recording/reproducing devices and digital storage mediums, and are not limited to the examples discussed above.
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|1||Boyce et al., "Fast Scan Technology for Digital Video Tape Recorders", IEEE Transactions on Consumer Electronics, vol. 39, No. 3, Aug. 1993, pp. 186-191.|
|2||Int's Organization for Standardization, ISO/IEC JTC1/SC29/WG11 MPEG 93/251, Mar. 1993, Jill Boyce et al. "Fast Scan Technology for MPEG Video Tape Recorders".|
|International Classification||G11B20/12, G11B27/10, H04N5/783, G11B20/10, H04N5/926, H04N9/82, G11B27/32, G11B15/12, H04N5/76, H04N9/79, H04N9/797, G11B15/18, G11B27/00, H04N9/804, G11B15/467, H04N5/92, G11B5/008, G11B15/48, G11B5/02, G11B27/30, H04N5/93, G11B15/52, H04N5/7826, G11B5/09, H04N5/91|
|Cooperative Classification||H04N19/61, G11B5/5927, G11B27/32, G11B5/09, G11B2220/91, H04N9/7973, H04N5/783, G11B2220/90, G11B27/324, H04N9/8042, G11B15/48, H04N5/782, H04N9/8205, G11B15/4673, H04N5/78266, G11B5/0086, G11B15/125, G11B27/3027, G11B15/1875, H04N5/78206, G11B27/005, G11B15/52, G11B27/107, H04N5/9262|
|European Classification||H04N5/782, G11B5/592A4H, H04N7/50, G11B27/32B2, H04N5/926B2, G11B27/32, H04N5/783, G11B27/10A2, G11B5/09, G11B5/008T4R, G11B27/00V, G11B27/30C, G11B15/18B3|