Apparatus and method for recording or reproducing digital data using speed information

Abstract

An apparatus and method for controlling recording and reproduction in a video cassette tape recorder are disclosed apparatus is capable of, in a recording mode, separating specific data for speed-varied reproduction from compressed digital video signals, recording them on designated tracks, 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 portions of the designated tracks recorded with the specific data, and in a speed-varied 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. A repeatability of reproduced video at a varied speed is obtained without any deterioration in picture quality, because of recording of the specific data for speed-varied reproduction and the continuous detection of the specific data in the speed-varied reproduction. Apparatus and method for controlling recording and/or reproduction of digital signals to and/or from a digital storage medium, are discussed. According to an embodiment, receiving the digital data, the digital data including video data compressed as at least one of intra-frame and predictive frame, stuffing data, synchronous signals, identification signals, and relative position information associated with an i-frame; detecting the synchronous signals and the identification signals for decoding the video data; obtaining the video data from the digital data by removing the stuffing data based on stuffing code information; determining a position associated with the i-frame by using the relative position information; determining whether a speed-varied reproduction mode is selected; and reproducing the video data based on the determined position associated with the i-frame, the synchronous signals, the identification signals, and a result of the step of determining whether the speed-varied reproduction mode is selected.

Description

VCRto and from a digital storage medium thefrom the storage medium

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 illustrative 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.

Claims

1. An apparatus for controlling recording and reproducing in a video cassette tape recorder comprising:

frame extracting means for buffering compressed digital data input thereto, and extracting specific data for a to speed-varied reproduction from said compressed digital data;

frame recording position controlling means for calculating a number of tracks for recording the compressed digital data and selectively outputting a buffered output, said extracted specific data from said frame extracting means, and a multiplexing timing signal;

frame position information recording means for recording position information of specific tracks for the speed-varied reproduction and index information on a magnetic tape, based on said multiplexing timing signal;

digital recording means for recording digital signals including said digital data and said index information on said magnetic tape;

digital reproduction means for reproducing the digital signals recorded on the magnetic tape;

frame position information detecting means for detecting said position information of the specific tracks for the speed-varied reproducing and said index information;

tape speed controlling means for controlling the speed of a capstan motor, based on said detected index information and said position information of the specific tracks; and

frame removing means for receiving an output from the digital reproduction means and removing unnecessary bit streams from the specific data.

2. An apparatus in accordance with claim 1, wherein said frame extracting means comprises:

an interface for receiving said compressed digital data;

a buffer for buffering an output of said interface for a predetermined period;

a frame detector for detecting said specific data from said output of the interface and outputting a write enable signal; and

a frame memory for selecting and storing the detected specific data, based on said write enable signal.

3. An apparatus in accordance with claim 2, wherein said frame detector counts a number of frames when a frame mark code is detected from a bit stream of said output of the interface, and enables said write enable signal when said counted number of frames is determined to be the same as an interval number at which i-frames are present.

4. An apparatus in accordance with claim 1, wherein said frame recording position controlling means comprises:

a track number calculator for calculating an average bit rate of said compressed digital data, the size of the specific data, a number of tracks for recording said specific data and a number of tracks present between said specific tracks;

a multiplexing timing generator for receiving an output from said track number calculator and outputting a switching signal for positioning the specific data on said specific tracks in accordance with a head switching signal;

a multiplexer for selecting an output from said frame extracting means, based on an output from said multiplexing timing generator and sending said selected output to said digital recording means; and

a bit stuffing circuit for filling insufficient data with bit streams or dummy bits when said selected output of the frame extracting means is at an underflow state.

5. An apparatus in accordance with claim 1, wherein said frame position information recording means comprises:

a frame position recorder for receiving an output from said frame recording position controlling means and outputting position discrimination information to said digital recording means so as to record position information of a next specific track on an initial synchronous block of a track having said specific data recorded thereon; and

an index signal recorder for recording position information of said track having said specific data recorded thereon on a control track of said magnetic tape by an index head.

6. An apparatus in accordance with claim 1, wherein said frame position information detecting means comprises:

an index signal detector for detecting index information recorded on a control track of said magnetic tape, said index information indicating whether tracks recorded with said specific data are present;

a recording position-synchronized block detector for detecting an output from said digital reproduction means and detecting recording position-synchronized blocks recorded with codes indicative of relative position information of said tracks recorded with said specific data; and

a recording position decoder for decoding an output of said recording position-synchronized block detector, based on a number of different tape speeds, and thereby outputting a signal for calculating a capstan servo speed.

7. An apparatus in accordance with claim 1, wherein said tape speed controlling means comprises:

a capstan servo speed calculator for calculating a capstan servo speed for repeating a normal speed travel on said specific tracks and a high speed travel on tracks between adjacent specific tracks in a speed-varied reproduction by using the position information of the specific track from said frame position information detecting means based on a number of different tape speeds; and

a capstan servo drive signal generator for controlling driving of said capstan motor, based on an output of said capstan servo speed calculator.

8. An apparatus in accordance with claim 1, wherein said frame removing means comprises:

a deformatter for converting an output of said digital reproduction means to a signal form prior to recording;

a stuffing bit-detecting and removing circuit for outputting a bit removing signal to said deformatter and removing stuffing bits or dummy bits added for preventing generation of an underflow of said frame extracting means in the speed-varied reproduction; and

a frame removal timing generator for receiving said position information of the specific tracks from said frame position information detecting means and outputting a frame removing signal to the deformatter, based on a head switching signal, thereby preventing outputting of said specific data in a normal-speed reproduction.

9. An apparatus in accordance with claim 1, wherein said specific data includes i-frames.

10. An apparatus in accordance with claim 1, wherein said digital recording means and said digital reproduction means include a plurality of heads and switches for selectively recording and reproducing the digital signals.

11. An apparatus for controlling recording in a video cassette tape recorder comprising:

frame extracting means for receiving compressed digital data input thereto and extracting specific data for a speed-varied reproduction from said compressed digital data;

frame recording position controlling means for generating a multiplexing timing signal and multiplexing said compressed digital data and said extracted specific data from said frame extracting means based on said multiplexing timing signal;

frame position information recording means for recording index information and position information of specific tracks for recording said specific data for the speed-varied reproduction on a magnetic tape based on said multiplexing timing signal; and

digital recording means for recording digital signals including said digital data and specific data from said frame recording position controlling means on the magnetic tape.

12. An apparatus in accordance with claim 11, wherein said frame extracting means includes:

an interface for receiving said compressed digital data;

a buffer for buffering an output of said interface for a predetermined period;

a frame detector for detecting said specific data from said output of the interface and outputting a write enable signal; and

a frame memory for selecting and storing said specific data based on said write enable signal.

13. An apparatus in accordance with claim 12, wherein said frame detector starts counting frames when a frame mark code is detected from a bit stream of said output of the interface, and enables said write enable signal when said counted frame number equals an interval number at which i-frames are present.

14. An apparatus in accordance with claim 11, wherein said frame recording position controlling means includes:

a track number calculator for calculating a number of said specific tracks for recording said specific data and a number of tracks present between said specific tracks;

a multiplexing timing generator for generating said multiplexing timing signal based on an output from said track number calculator; and

a multiplexer for selecting an output from said frame extracting means based on said generated multiplexing timing signal.

15. An apparatus in accordance with claim 14, wherein said frame recording position controlling means includes a bit stuffing circuit for filling insufficient data with bit streams or dummy bits when said selected output of the frame extracting means is at an underflow state.

16. An apparatus in accordance with claim 11, wherein said frame position information recording means includes:

a frame position recorder for receiving an output from said frame recording position controlling means and outputting position discrimination information to said digital recording means so as to record said position information of said specific tracks; and

an index signal recorder for recording said index information on a control track of the magnetic tape, said index information including information indicating whether said specific tracks for said specific data are present.

17. An apparatus in accordance with claim 11, wherein said specific data includes i-frames, and said digital recording means includes a plurality of heads and switches for selectively recording said digital signals.

18. An apparatus in accordance with claim 11, wherein said digital recording means includes an interleaving and channel driving circuit, a plurality recording formatters, and a plurality of channel modulators, for formatting said digital signals so as to record said digital signals on the magnetic tape.

19. A method for controlling recording and reproduction in a video cassette tape recorder, comprising the steps of:

extracting specific data for a speed varied reproduction from compressed digital data;

calculating a number of tracks for recording said digital data and outputting a multiplexing timing signal based on said calculated number of tracks;

recording position information of specific tracks for the speed varied reproduction and index information on a magnetic tape based on said multiplexing timing signal;

recording digital signals including said digital data and said index information on the magnetic tape;

reproducing said digital signals recorded on the magnetic tape;

detecting said position information of the specific tracks for the speed varied reproduction and said index information;

controlling the speed of a capstan motor based on said detected index information and position information of the specific tracks; and

removing unnecessary bit streams from said specific data.

20. A method in accordance with claim 19, wherein said specific data includes i-frames.

21. A method of controlling recording in a video cassette tape recorder, comprising the steps of:

extracting specific data for a speed-varied reproduction from compressed digital data;

generating a multiplexing timing signal and multiplexing said compressed digital data and said extracted specific data based on said multiplexing timing signal;

recording index information and position information of specific tracks for recording said specific data for the speed-varied reproduction on a magnetic tape based on said multiplexing timing signal; and

recording digital signals including said multiplexed digital data and specific data on the magnetic tape.

22. A method in accordance with claim 21, wherein said generating step includes calculating a number of tracks for recording said digital data and generating said multiplexing timing signal based on said calculated number of tracks.

23. A method for processing digital data, the method performed by at least one device and comprising:

receiving the digital data,

wherein the digital data includes video data compressed as at least one of intra-frame and predictive frame, stuffing data capable of being detected and removed, synchronous signals, identification signals, and at least one relative position information associated with an i-frame, wherein the relative position information indicates position information associated with the i-frame relative to position information associated with a current frame;

detecting the synchronous signals and the identification signals for decoding the video data;

obtaining the video data from the digital data by removing the stuffing data based on stuffing code information;

determining a position associated with the i-frame by using the relative position information;

determining whether a speed-varied reproduction mode is selected for reproduction of the video data in a varied speed; and

reproducing the video data based on the determined position associated with the i-frame, the synchronous signals, the identification signals, and a result of the step of determining whether the speed-varied reproduction mode is selected.

24. The method of claim 23, wherein the digital data further includes index information indicating that the video data includes an i-frame, and the current frame includes video information and header information.

25. The method of claim 23, wherein the relative position information indicates a position difference between an area associated with the current frame and an area associated with the i-frame.

26. The method of claim 23, wherein the reproducing step reproduces the video data 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.

27. The method of claim 23, further comprising:

reproducing the video data in a normal speed if the determining step determines that the speed-varied reproduction mode is not selected.