Apparatus and method for controlling recording and reproduction in digital video cassette tape recorder

Abstract

An apparatus and method for controlling recording and reproduction in a video cassette tape recorder are disclosed. The 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.

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 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. An apparatus for controlling recording in a digital video recording device, comprising:
   an input unit receiving digital video data, the digital video data including I - frames of intra - coded digital picture data;        a data generating circuit generating a plurality of relative position data, each of the plurality of relative position data associated with one of a plurality of specific data in the received digital video data, wherein the specific data includes the intra - coded digital picture data, and wherein each of the plurality of relative position data is indicative of a plurality of relative positions from a current nth specific data location on a digital recording medium to each of a n+ 1 , n+ 2 , . . . , n+m specific data location on the digital recording medium, where m is greater than  2 ; and        a recording unit coupled to the data generating circuit and recording the digital video data and the plurality of relative position data on the digital recording medium such that each specific data includes the associated relative position data, as well as the intra - coded digital picture data.     
     
     
       24. The apparatus of  claim 23 , further comprising:
   a detection circuit coupled to the input unit and detecting the specific data from the received digital video data; and wherein        the data generating circuit is coupled to the detection circuit.     
     
     
       25. The apparatus of  claim 24 , wherein the data generating circuit includes:
   a timing signal generating circuit generating a timing control signal; and        a multiplexer coupled to the timing signal generating circuit and selectively outputting the detected specific data and the digital video data based on the timing control signal.     
     
     
       26. The apparatus of  claim 23 , wherein the digital medium includes a magnetic medium. 
     
     
       27. The apparatus of  claim 23 , wherein each of the plurality of relative position data includes a plurality of distance indicators, each distance indicator indicating a distance between the current nth specific data location and one of the n+ 1 , n+ 2 , . . . , n+m specific data locations. 
     
     
       28. The apparatus of  claim 27 , wherein said distance is represented with a number of distance units present between the current nth specific data location and one of the n+ 1 , n+ 2 , . . . , n+m specific data locations. 
     
     
       29. The apparatus of  claim 28 , wherein the distance unit is a track on the storage medium. 
     
     
       30. The apparatus of  claim 23 , wherein the recording unit includes:
   a formatting circuit forming a data block associated with each specific data, the data block including the associated relative position data.     
     
     
       31. An apparatus for controlling reproduction in a digital video reproducing device, comprising:
   a reproducing unit reproducing digital video data, the digital video data including I - frames of intra - coded digital picture data stored on a digital recording medium, the digital data including a plurality of specific data, each of said plurality of specific data including relative position data and intra - coded digital picture data, each relative position data indicative of a plurality of relative positions from a current nth specific data location on a digital recording medium to each of a n+ 1 , n+ 2 , . . . , n+m specific data location on the digital recording medium, where m is greater than  2 ;        a detection circuit coupled to the reproducing unit and detecting one of the plurality of relative position data from the reproduced digital video data; and        a control circuit coupled to the detection circuit, receiving a command and controlling the reproducing unit to reproduce at least another specific data based on the detected relative position data and the command.     
     
     
       32. The apparatus of  claim 31 , wherein the detection circuit includes:
   a decoding circuit selecting one of the relative positions represented in said detected relative position data based on the command.     
     
     
       33. The apparatus of  claim 31 , wherein each of the plurality of relative position data includes a plurality of distance indicators, each distance indicator indicating a distance between the current nth specific data location and one of the n+ 1 , n+ 2 , . . . , n+m specific data locations. 
     
     
       34. The apparatus of  claim 33 , wherein said distance is represented with a number of distance units present between the current nth specific data location and one of the n+ 1 , n+ 2 , . . . , n+m specific data locations. 
     
     
       35. The apparatus of  claim 34 , wherein the distance unit is a track on the digital medium. 
     
     
       36. The apparatus of  claim 31 , wherein the reproducing unit includes a motor for moving the digital medium. 
     
     
       37. The apparatus of  claim 36 , wherein the control circuit includes:
   a calculating circuit calculating a rotational speed of the motor based on the detected relative position data.     
     
     
       38. The apparatus of  claim 31 , wherein the reproducing unit includes reading heads and signal processing circuits. 
     
     
       39. A method for controlling recording in a digital video recording device, comprising the steps of:
   receiving digital video data, the digital video data including I - frames of intra - coded digital picture data;        generating a plurality of relative position data, each of the plurality of relative position data associated with one of a plurality of specific data in the received digital video data, wherein the specific data includes the intra - coded digital picture data, and wherein each of the plurality of relative position data is indicative of a plurality of relative positions from a current nth specific data location on a digital recording medium to each of a n+ 1 , n+ 2 , . . . , n+m specific data location on the digital recording medium, where m is greater than  2 ; and        recording the digital video data and the plurality of relative position data on the digital medium such that each specific data includes the associated relative position data, as well as the intra - coded digital picture data.     
     
     
       40. The method of  claim 39 , further comprising the step of:
   generating a timing control signal; and        wherein said recording step includes,        recording the digital video data and the specific data based on the timing control signal.     
     
     
       41. The method of  claim 39 , wherein in said recording step, the digital medium includes a magnetic medium. 
     
     
       42. The method of  claim 39 , wherein each of the plurality of relative position data includes a plurality of distance indicators, each distance indicator indicating a distance between the current nth specific data location and one of the n+ 1 , n+ 2 , . . . , n+m specific data locations. 
     
     
       43. The method of  claim 42 , wherein said distance is represented with a number of distance units present between the current nth specific data location and one of the n+ 1 , n+ 2 , . . . , n+m specific data locations. 
     
     
       44. The method of  claim 43 , wherein the distance unit is a track on the digital medium. 
     
     
       45. The method of  claim 39 , wherein said recording step includes the step of:
   forming a data block associated with each specific data, the data block including the associated relative position data.     
     
     
       46. A method for controlling reproduction in a digital video reproducing device, comprising the steps of:
   reproducing digital video data, the digital video data including I - frames of intra - coded digital picture data stored on a digital recording medium, the digital video data including a plurality of specific data, each of said plurality of specific data including relative position data and intra - coded digital picture data, each relative position data indicative of a plurality of relative positions from a current nth specific data location on a digital recording medium to each of a n+ 1 , n+ 2 , . . . , n+m specific data location on the digital recording medium, where m is greater than  2 ;        detecting one of the plurality of relative position data from the reproduced digital video data;        receiving a command; and        reproducing at least another specific data based on the detected relative position data and the command.     
     
     
       47. The method of  claim 46 , wherein said reproducing step includes the step of:
   decoding the detected relative position data by selecting one of the relative positions represented in the detected relative position data based on the command to reproduce the at least another specific data.     
     
     
       48. The method of  claim 46 , wherein each of the plurality of relative position data includes a plurality of distance indicators, each distance indicator indicating a distance between the current nth specific data location and one of the n+ 1 , n+ 2 , . . . , n+m specific data locations. 
     
     
       49. The method of  claim 48 , wherein said distance is represented with a number of distance units present between the current nth specific data location and one of the n+ 1 , n+ 2 , . . . , n+m specific data locations. 
     
     
       50. The method of  claim 49 , wherein the distance unit is a track on the digital medium. 
     
     
       51. The method of  claim 46 , wherein said reproducing step includes the step of:
   calculating a rotational speed of a motor for moving the digital medium based on the detected relative position data.     
     
     
       52. A digital video recording medium having a data structure for controlling a reproducing operation, comprising:
   a plurality of specific data areas, each specific data area storing digital specific data including intra - coded digital picture data and associated relative position data, the associated relative position data indicative of a plurality of relative positions from a current nth specific data location on the digital video recording medium to each of a n+ 1 , n+ 2 , . . . , n+m specific data location on the digital video recording medium, where m is greater than  2 .