Abstract:
The present invention has been made to reproduce data such as video or sound while preventing a video image from being reproduced in a discontinuous manner with respect to a previously reproduced still image in a reproducing apparatus that reproduces a video image and still image that operate in accordance with time information for synchronous reproduction and that have been recorded on a recording medium according to a recording system in which the data size corresponding to one frame is variable. When the reproducing apparatus operates in accordance with time information for synchronous reproduction to reproduce a video image and still image recorded in a recording medium according to a recording system in which the size of data corresponding to one frame is variable, the recording medium is stopped or reversely driven after all the data of the last bank have been picked up or after the reproduction position on the tape has passed over the last bank at the time when the operation mode of the reproducing apparatus is switched from video image reproduction mode to still image reproduction mode.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
       [0001]     The present invention contains subject matter related to Japanese Patent Application JP 2004-250821 filed in Japanese Patent Office on Aug. 30, 2004, the entire contents of which being incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a reproduction control method for use in a recording/reproducing apparatus such as a video tape recorder and a reproducing apparatus.  
         [0004]     2. Description of the Related Art  
         [0005]     When a tape drive is once stopped for reproduction of a still image, and the tape drive is restarted for video reproduction in a tape recording/reproducing apparatus, the video image is reproduced in a discontinuous manner with respect to the still image that has been reproduced up to then, in some cases.  
         [0006]     To solve the above problem, a method of rewinding the tape simply while controlling the tape drive distance and tape drive timing has been used (refer to, for example, Jpn. Pat. Appln. Publication No. Hei. 7-75413).  
         [0007]     A format for compressing video data according to, for example, an HDV system and recording the video data on a magnetic tape has been specified as an HDV format of a digital video tape recorder. With this format, variable length data having a variable frame size such as an MPEG-PES (Packtized Elementary Stream) is recorded on a magnetic tape (refer to, for example, Jpn. Pat. Appln. Laid-Open Publication No. 2004-164731).  
       SUMMARY OF THE INVENTION  
       [0008]     However, in the case where video data is recorded on the magnetic tape according to a recording system in which the data size corresponding to one frame is variable, such as the MPEG-PES, the tape drive distance differs from the number of reproduced frames, so that it has been impossible to solve the above problem simply by controlling the tape drive distance and its drive timing. The reason is that even when the tape is rewound by the same distance, there is no certainty that the same number of frames has been rewound.  
         [0009]     In view of the above situation, it is desirable to reproduce data such as video or sound while preventing a video image from being reproduced in a discontinuous manner with respect to a previously reproduced still image in a reproducing apparatus that operates with time information for synchronous reproduction and reproduces a video image and still image that have been recorded on a recording medium according to a recording system in which the data size corresponding to one frame is variable.  
         [0010]     The advantages and features of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings.  
         [0011]     According to the present invention, there is provided a reproduction control method for use in a reproducing apparatus which operates in accordance with time information for synchronous reproduction to reproduce a video image and still image which are recorded in a recording medium according to a recording system in which the size of data corresponding to one frame is variable, including the step of: stopping or reversely driving the recording medium after all the data of the last bank have been picked up or after the reproduction position on the tape has passed over the last bank at the time when the operation mode of the reproducing apparatus is switched from video image reproduction mode to still image reproduction mode.  
         [0012]     According to the present invention, there is provided a reproduction control method for use in a reproducing apparatus which operates in accordance with time information for synchronous reproduction to reproduce a video image and still image which are recorded in a recording medium according to a recording system in which the size of data corresponding to one frame is variable, including the steps of: once rewinding the recording medium in the backward direction with respect to the reproduction direction at the time when the operation mode of the reproducing apparatus is switched from still image reproduction mode to video image reproduction mode; restarting drive of the recording medium in the forward direction while reading out the time information for synchronous reproduction recorded in the recording medium; calculating decode time based on the time information for synchronous reproduction that has been read out from the recording medium before or during approach run and rewinding reference time depending on the calculation result; restarting supply of the reproduced data based on a result obtained by comparing the reference time of which measurement has been restarted from the reference time that had been rewound before or during the approach run and decode time; and latching the reference time of which measurement has been restarted from the reference time that had been rewound before or during the approach run and restarting a video reproduction according to a result obtained by comparing the reference time, decode time, and presentation time.  
         [0013]     According to the present invention, there is provided a reproducing apparatus which operates in accordance with time information for synchronous reproduction to reproduce a video image and still image which are recorded in a recording medium according to a recording system in which the size of data corresponding to one frame is variable, including: control means for stopping or reversely driving the recording medium after all the data of the last bank have been picked up or after the reproduction position on the tape has passed over the last bank at the time when the operation mode of the reproducing apparatus is switched from video image reproduction mode to still image reproduction mode.  
         [0014]     According to the present invention, there is provided a reproducing apparatus which operates in accordance with time information for synchronous reproduction to reproduce a video image and still image which are recorded in a recording medium according to a recording system in which the size of data corresponding to one frame is variable, including: drive means for driving the recording medium in the forward direction or backward direction; reproduction processing means for reproducing the data from a reproduced signal obtained from the recording medium driven by the drive means; decode processing means for decoding the data reproduced by the reproduction processing means and outputting the decoded data; and control means for controlling the operations of the above means, wherein, at the time when the operation mode of the reproducing apparatus is switched from still image reproduction mode to video image reproduction mode, the control means once rewinds the recording medium in the direction opposite to the reproduction direction; restarts drive of the recording medium in the forward direction while reading out the time information for synchronous reproduction recorded in the recording medium; calculates decode time based on the time information for synchronous reproduction that the reproduction processing means has read out from the recording medium before or during approach run; rewinds the reference time depending on the calculation result; restarts supply of the reproduced data based on a result obtained by comparing the reference time of which measurement has been restarted from the reference time that had been rewound before or during the approach run and decode time; allows the decode processing means to latch the reference time of which measurement has been restarted from the reference time that had been rewound before or during the approach run; and restarts a video reproduction according to a result obtained by comparing the reference time, decode time, and presentation time.  
         [0015]     According to the present invention, it is possible to reproduce data such as video or sound while preventing a video image from being reproduced in a discontinuous manner with respect to a previously reproduced still image in a reproducing apparatus which operates in accordance with time information for synchronous reproduction to reproduce a video image and still image which are recorded in a recording medium according to a recording system in which the size of data corresponding to one frame is variable. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a block diagram showing a configuration of a reproducing apparatus according to the present invention;  
         [0017]      FIG. 2  is a view schematically showing a video data recording state on a magnetic tape in the reproducing apparatus;  
         [0018]      FIG. 3  is a view schematically showing a tape drive state in the case where operation mode in the reproducing apparatus is switched from video image reproduction (PB) mode to still image reproduction (PB Pause) mode, and then switched from still image reproduction (PB Pause) mode to video image reproduction (PB) mode;  
         [0019]      FIG. 4  is a view schematically showing operations of respective sections in the reproducing apparatus when the operation mode is switched from video image reproduction (PB) mode to still image reproduction (PB Pause) mode; and  
         [0020]      FIG. 5  is a view schematically showing operations of respective sections in the reproducing apparatus when the operation mode is switched from still image reproduction (PB Pause) mode to video image reproduction (PB) mode. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited to the following embodiment and can be arbitrarily modified without departing from the spirit and scope of the invention.  
         [0022]     The present invention is applied, for example, to a reproducing apparatus  100  as shown in  FIG. 1 .  
         [0023]     The reproducing apparatus  100  includes a mechanical deck section  10  for tape drive, a reproduction signal processing section  20  to which a reproduced signal is supplied from the mechanical deck section  10  for tape drive, a decode processing section  30  to which reproduced data obtained by the reproduction signal processing section  20  is supplied, and a system controller  40  which controls the above sections.  
         [0024]     In the reproducing apparatus  100 , the mechanical deck section  10  includes a tape running system  11  allows a magnetic tape  50  to run, and a rotation head  12  which scans tracks on the magnetic tape  50 . The mechanical deck section  10  allows the rotation head  12  to scan the magnetic tape  50  driven by the tape running system  11  to obtain a reproduced signal and supplies the reproduction signal processing section  20  with the obtained reproduced signal.  
         [0025]     On the magnetic tape, MPEG-PES data in which the data size corresponding to one frame is variable has been recorded as shown in  FIG. 2 .  FIG. 2  shows a recording state of video data having a GOP structure of N=15 (I-picture is placed every 15 pictures) and M=3 (P-picture is placed every 3 pictures) on the magnetic tape. That is, one pack is constituted by M (three, in this case) picture data, AUX data (AUX-V: U in  FIG. 2 ) related to the picture, audio data (A in  FIG. 2 ) related to the picture, and AUX data (AUX-A: X in  FIG. 2 ) related to the audio data.  
         [0026]     The above video data is subjected to ECC (Error Correcting Code) processing with data corresponding to  16  tracks as a unit, and thereby ECCTB (Error Correction Code Table Block) (H in  FIG. 2 : packet placed in a sync block to be assigned to the recording of the top of ECC block) storing predetermined information is placed on the first track of every 16 tracks. A unit including 16 tracks, which is a unit of ECC processing, is referred to as ECC bank.  
         [0027]     In the reproducing apparatus  100 , the reproduction signal processing section  20  includes an ECC bank memory  21 , a video delay memory  22 , an STC counter  23 , a reproduction control microcomputer  24  and the like. Reproduced unit data per the ECC processing is fetched from the reproduced signal obtained by the mechanical deck section  10  for tape drive and is written into the ECC bank memory  21 . The reproduced unit data per the ECC processing that has been written into the ECC bank memory  21  is then subjected to error correcting processing and is supplied to the decode processing section  30  through the video delay memory  22 .  
         [0028]     In the reproducing apparatus  100 , the decode processing section  30  includes a bit stream buffer  31 , a decoder  32 , a decode control microcomputer  33 , and the like. The reproduced data obtained by the reproduction signal processing section  20  is supplied to the decoder  32  through the bit stream buffer  31 . The decoder  32  then decodes the reproduced data and outputs the decoded data.  
         [0029]     Next, an operation of the reproducing apparatus  100  having the above configuration will be described. Here, the magnetic tape  50  is driven and operation mode in the reproducing apparatus is switched from video image reproduction (PB) mode to still image reproduction (PB Pause) mode, and then switched from still image reproduction (PB Pause) mode to video image reproduction (PB) mode, as shown in  FIG. 3 .  
         [0030]     Operations of the mechanical deck section  10  for tape drive, reproduction signal processing section  20  to which a reproduced signal is supplied from the mechanical deck section  10  for tape drive, decode processing section  30  to which the reproduced signal obtained by the reproduction signal processing section  20  is supplied, and system controller  40  which controls the above sections at the time when the operation mode of the reproducing apparatus  100  is switched from video image reproduction (PB) mode to still image reproduction (PB Pause) mode are shown in  FIG. 4 .  
         [0031]     When the operation mode is switched from video image reproduction (PB) mode to still image reproduction (PB Pause) mode, the system controller  40  does not stop tape drive in the middle of bank, but waits for image output(A 1 ) and stops the tape drive after pick-up of all the data of the last bank (A 2 ), or waits for the reproduction position on the tape to pass over the last bank and stops the tape drive in the bank subsequent to the last bank. Thereafter, the system controller  40  requests the reproduction control microcomputer  24  of the reproduction signal processing section  20  to switch the operation mode to still image reproduction mode (PB Pause) and requests the decode control microcomputer  33  of the decode processing section  30  to perform reproduction end (PB END) processing (A 3 ).  
         [0032]     Upon receiving the operation mode switch request (to PB pause) from the system controller  40 , the decode control microcomputer  33  of the decode processing section  30  stops the supply of the reproduced data obtained by the reproduction signal processing section  20  to the decoder  32  through the bit stream buffer  31  to allow the decoder  32  to stop the decode of the reproduced data to thereby stop the reproduction data output (B 1 ) and notifies the system controller  40  of DTS (Decoding time stamp) to be decoded next (B 2 ).  
         [0033]     Upon receiving the reproduction end (PB END) request from the system controller  40 , the reproduction control microcomputer  24  of the reproduction signal processing section  20  performs the reproduction end processing (C 1 ) and notifies the system controller  40  of the completion of the reproduction end processing.  
         [0034]     Upon receiving the notification of the completion of the reproduction end processing from the reproduction control microcomputer  24  of the reproduction signal processing section  20 , the system controller  40  requests the reproduction control microcomputer  24  to switch the operation mode to still image reproduction (PB Pause) mode (A 4 ) and stores a first ETN (Extended track number) of the last bank or immediately subsequent bank (A 5 ).  
         [0035]     Upon receiving the operation mode switch request (to PB pause) from the system controller  40 , the reproduction control microcomputer  24  of the reproduction signal processing section  20  performs processing of still image reproduction (PB Pause) mode.  
         [0036]     ETN (Extended track number) is track number that can be obtained by converting DTS (Decoding time stamp). The following relationship exists between ETN and DTS: 
 
DTS=(ETN−10)×(clock number/10) 
 
 where clock number is 3003 in the case of NTSC and 3600 in the case of PAL. 
 
         [0037]     Next, operations of the mechanical deck section  10  for tape drive, reproduction signal processing section  20  to which a reproduced signal is supplied from the mechanical deck section  10  for tape drive, decode processing section  30  to which reproduced data obtained by the reproduction signal processing section  20  is supplied, and system controller  40  which controls the above sections at the time when the operation mode of the reproducing apparatus  100  is switched from still image reproduction (PB Pause) mode to video image reproduction (PB) mode are shown in  FIG. 5 .  
         [0038]     When the operation mode is switched from still image reproduction (PB Pause) mode to video image reproduction (PB) mode, the system controller  40  uses the stored ETN (Extended track number) and DTS (Decoding time stamp) notified by the decode control microcomputer  33  of the decode processing section  30  in the abovementioned operation switch control from video image reproduction (PB) mode to still image reproduction (PB Pause) mode to determine a tape rewind amount and writing start bank (A 11 ). The system controller  40  then once rewinds the magnetic tape  50  and, after that, forwards the magnetic tape  50  (A 12 ). The system controller  40  then requests the reproduction control microcomputer  24  of the reproduction signal processing section  20  and the decode control microcomputer  33  of the decode processing section  30  to switch the operation mode to video reproduction (PB) mode (A 13 ).  
         [0039]     As a result, the tape drive is restarted in the forward direction (approach run) while the system controller  40  reads out time information (ETN) for synchronous reproduction recorded on the magnetic tape  50 .  
         [0040]     The system controller  40  then calculates decode time (DTS) from the time information (ETN) for synchronous reproduction that has been read out from the magnetic tape  50  before or during the approach run and, depending on the calculation result, rewinds the reference time (STC) of the decode processing section  30  and reproduction signal processing section  20  (A 14 ).  
         [0041]     The reproduction control microcomputer  24  of the reproduction signal processing section  20  restarts measurement using the STC counter  23  (C 11 ) from the reference time (STC) that has been rewound by the system controller  40  before or during the approach run, compares the reference time (STC) measured using the STC counter  23  and decode time (DTS), and restarts supply of reproduced data to the decode processing section  30  (C 12 ) according to the comparison result (STC&gt;DTS−VBV_Delay−offset due to hardware delay, etc.).  
         [0042]     VBV_Delay is a delay of the video delay memory  22 .  
         [0043]     The decode control microcomputer  33  of the decode processing section  30  latches, from the STC counter  23  of the reproduction signal processing section  20 , the reference time (STC) the measurement of which has been restarted from the reference time (STC) that had been rewound before or during the approach run and restarts video reproduction (B 1 ) according to a result obtained by comparing the latched reference time (STC), decode time (DTS), and presentation time (PTS: Presentation Time Stamp).  
         [0044]     The reproducing apparatus  100  that performs the above processing uses, at the time of restart of video reproduction, time information (ETN) (track number that can be obtained by converting decode time (DTS)) for synchronous reproduction to adjust the rewinding amount of reference time (STC) and tape drive timing and restarts video reproduction based on the rewound reference time (STC), thereby preventing the restarted video image from being reproduced in a discontinuous manner with respect to a previously reproduced still image.  
         [0045]     The tape distance to be rewound in the tape end direction is defined by [(average track number per one picture)×(picture number needed to be retrieved from buffer by the time when tape position returns to ETN corresponding to stop position)+(distance needed to wait for stable state of tape path running)+(distance needed to accelerate up to one-fold speed to achieve tracking)]. The tape may be rewound by an extra distance for allowing a margin.  
         [0046]     The above method adjusts the number of pictures to be used up in decode processing by the time when the tape position returns to ETN corresponding to the stop position and timing at which data supply to the buffer is restarted, thereby preventing a buffer overflow.  
         [0047]     Alternatively, in addition to the above method in which the tape rewind distance changes depending on the number of pictures needed to be retrieved from the buffer, another method can be employed, in which stop time may be provided for the tape drive in order to adjust the time until the restart of PB so that the number of pictures needed to be retrieved from the buffer by the time when the tape position returns to ETN corresponding to the stop position are used up.  
         [0048]     It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alternations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.