JPH1169282A - Video tape recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve convenience by setting a magnetic tape at a prescribed waiting position with respect to a video signal outputted at the last within the range of the process delay of stopping, in the case of stopping the reproduction of the magnetic tape, thereby shortening the waiting time at the time of starting reproduction by switching a reproducing direction. SOLUTION: A tape-traveling control circuit 9 discriminates the presence/ absence of the accumulation of a prescribed data quantity in a reproducing memory 5 via a reproducing memory control circuit 11 with the command of a system control circuit 12, when the reproduction of the magnetic tape 2 is instructed. Next, when traveling is stopped, the tape 2 is stooped at a position preceding by the portion of process delay and the memory 5 stores AV signals in a reproducing process. Consequently, in a period from the restart of reproduction from the stopping position of the tape 2 until the AV signal delaying the process delaying portion becomes capable of being output, the AV signals held in the memory 5 are successively sent out. Thereby, consecutive AV signals is outputted continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video tape recorder, and more particularly to a video tape recorder, such as MPEG (Moving Picture Experts).
Group) format and can be applied to a video tape recorder that reproduces a video signal recorded after data compression. According to the present invention, when reproduction of a magnetic tape is stopped for a process delay until a video signal is demodulated from a reproduction signal output from a magnetic head, a magnetic field corresponding to a video signal output last within a range of the process delay is stopped. By setting the position of the tape, the waiting time in the case where the direction is switched and the reproduction is resumed is reduced, and the usability is improved.

[0002]

2. Description of the Related Art Hitherto, there has been proposed a video tape recorder capable of recording a video signal at a high density by compressing the video signal.

[0003] That is, this type of video tape recorder converts a sequentially input video signal into a luminance signal and a color difference signal, and then converts the luminance signal and the color difference signal into digital signals. Further, these digital signals are data-compressed in a format prescribed by, for example, MPEG, and an error-correcting code is added to the resulting compressed video signal in a predetermined block unit, followed by shuffling and recording on a magnetic tape. ing.

[0004]

When reproducing a video signal recorded on a magnetic tape in this way, the video tape recorder demodulates a bit stream from a reproduced signal output from a magnetic head and then performs a deshuffling process. To demodulate the compressed video signal in the original arrangement.
Further, the compressed video signal is subjected to data expansion, thereby demodulating the original luminance signal and color difference signal. As a result, in this type of video tape recorder, a time delay (hereinafter referred to as a process delay) occurs between the time when the video signal is reproduced by running the magnetic tape and the time when the video signal is actually demodulated and output. ) Can not be avoided.

When such a process delay is large,
Generally, it takes time from the start of the reproduction of the magnetic tape by the operation of the operation unit to the start of the actual movement of the image, which generally impairs the accessibility. As a result, in this type of video tape recorder, there is a problem that the usability at the time of editing work is still insufficient for practical use.

The present invention has been made in view of the above points, and it is an object of the present invention to propose a video tape recorder capable of improving usability in this type of video tape recorder.

[0007]

According to the present invention, a video signal is output by performing signal processing on a reproduced signal output from a magnetic head in a period of a plurality of frames of the video signal. When the reproduction of the magnetic tape is stopped, the magnetic tape is displaced to a predetermined standby position,
This standby position is set so that the position of the magnetic tape is a position of a plurality of frames or less earlier than the video signal at the time when the reproduction of the magnetic tape is stopped.

After the reproduction of the magnetic tape is stopped, the magnetic tape is displaced to a predetermined standby position, and the standby position is such that the position of the magnetic tape corresponds to the video signal at the time when the reproduction of the magnetic tape is stopped. By setting the position at a position of a plurality of frames or less required for signal processing, in the case of subsequently switching the direction and reproducing, it is possible to reduce the waiting time until the video signal following the frame where reproduction is stopped is output. it can.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 is a block diagram showing a reproduction system of the video tape recorder according to the embodiment of the present invention. This video tape recorder 1 converts a digital video signal into M
The data is compressed in the PEG format and recorded on the magnetic tape 2 together with the digital audio signal. The digital video signal and digital audio signal recorded on the magnetic tape 2 are reproduced and output.

In this digital video signal recording system, the video tape recorder 1 alternately sets continuous frames of the digital video signal to I-pictures and B-pictures as shown in FIG. For the B picture, the digital video signal is data-compressed by a bidirectional prediction in which the preceding and succeeding I pictures are set as prediction frames by the inner coding processing to generate a compressed video signal.

Further, the video tape recorder 1 adds an error correction code of a product code format to video data constituting the compressed video signal in units of two frames, and
Shuffling processing is performed by interposing D data or the like. Further, the shuffled compressed video signal is time-division multiplexed with the digital audio signal, and is converted into a recording signal by a predetermined modulation method. The video tape recorder 1 drives the magnetic head 3 based on the recording signal, and converts the digital video signal and the digital audio signal to the magnetic tape 2.
To record.

The reproduction signal processing circuit 4 receives the reproduction signal RF obtained from the magnetic head 3, performs signal processing by processing corresponding to the recording system, and demodulates a digital video signal and a digital audio signal.

That is, as shown in FIG. 4, in the reproduction signal processing circuit 4, the demodulation circuit 4A equalizes the waveform of the reproduction signal RF, then binarizes the signal RF at a predetermined slice level, and obtains the resulting binarized signal. Regenerate the clock more. Further, the demodulation circuit 4A demodulates the reproduction data from the reproduction signal RF by sequentially latching the binary signal based on the clock. Further, the demodulation circuit 4A processes the reproduced data by a demodulation method corresponding to the modulation method at the time of recording to generate demodulated data D1.

The deshuffling circuit 4B performs a deshuffling process on the demodulated data D1 based on the ID data added to the demodulated data D1, and outputs the data. The inner code error correction circuit 4C receives the demodulated data D1 from the deshuffling circuit 4B, performs error correction processing using an inner code error correction code among the product code format error correction codes added to the demodulated data D1, and outputs the result. I do. The outer code error correction circuit 4D outputs the output data D1 of the inner code error correction circuit 4C.
Then, the data is subjected to error correction processing using an error correction code formed of an outer code and output.

The packing circuit 4E receives the output data of the outer code error correction circuit 4D, converts the output data into serial data SDDI of a predetermined format, and outputs the converted data, for example, to an externally connected hard disk device.
Here, this format is a transmission format defined for digital video signals and digital audio signals that have been data-compressed in the MPEG format. Further, at the time of fast forward reproduction in the forward direction and the reverse direction, the packing circuit 4E generates and outputs serial data SDDI based on the compressed video signal assigned to the I picture among the compressed video signals obtained intermittently.

The unpacking circuit 4F converts the output data of the packing circuit 4E into a format suitable for the subsequent processing of the decoder 4G. The decoder 4G converts the output data of the unpacking circuit 4F into the original digital video signal, digital audio signal and digital audio signal. The signal is decoded and output.

Thus, in the reproducing system of the video tape recorder 1, when reproducing the magnetic tape in the normal mode (in the case of forward reproduction at 1 × speed),
With respect to the reproduction signal RF obtained from the magnetic tape 2, the digital video signal (same for digital audio signal) DV output from the decoder 4G is output with a delay of 9 frames.

That is, in this embodiment, by shuffling and recording the compressed video signal in units of two frames, a delay of two frames cannot be avoided when deshuffling by the deshuffling circuit 4B. In the subsequent error correction using the inner code, a delay time of approximately one frame occurs. Thereby, the outer code error correction circuit 4
The compressed video signal (FIG. 5 (B)) input to D corresponds to the reproduction signal RF output from the magnetic head 3 (FIG. 5).
(A)) Delay by three frames. Further, after error correction processing is performed by the outer code error correction circuit 4D (FIG. 5C), a delay time of three frames is generated when the data is converted into serial data SDDI by the packing circuit 4E (FIG. 5D). ),
In the decoder 4G following the unpacking circuit 4F,
In order to decode a B picture by bidirectional prediction, a delay time of three frames occurs (FIG. 5E).

As a result, the digital video signal DV finally output from the decoder 4G and visually checked by the monitor by the monitor is delayed by nine frames with respect to the reproduction signal RF output from the magnetic head 3. That is, a process delay for nine frames occurs. Therefore, for example, the first of the digital video signal DV
If the operator stops the running of the magnetic tape 2 and switches the operation mode of the video tape recorder 1 to the still mode when the 0 frame is displayed on the monitor device, the magnetic head 3 Then, the scanning of the portion where the compressed video signal of the 19th frame is recorded is completed, and the digital video signals from the 11th frame to the 19th frame are held in the demodulation process in this reproduction system.

In this embodiment, this reproduction system
Even after the operation is switched in this way, the digital video signal in the demodulation process is continuously subjected to demodulation processing and output from the decoder 4G. Further, the output of the digital video signal in the demodulation process to the external device is stopped, and the digital video signal is recorded in the reproduction memory 5 together with the corresponding digital audio signal. Hereinafter, the digital video signal and the corresponding digital audio signal are referred to as an AV signal.

On the other hand, when the magnetic tape is reproduced in reverse (in the case of reverse reproduction at 1 × speed), a process delay of 15 frames occurs. That is, in this case,
The decoder 4G waits for the decoding of the compressed video signal composed of the I and B pictures previously recorded on the magnetic tape 2 and then decodes the subsequent B picture on the magnetic tape 2 to perform forward reproduction. In this case, a delay time of 7 frames is generated, which is 4 frames longer than in the case of, and a delay time of 2 frames is generated in rearranging the frames.

Thus, in reverse playback, when the operator stops the running of the magnetic tape 2 and switches the operation mode of the video tape recorder 1 to the still mode, a digital video signal for 15 frames is generated.
In this reproduction system, it is held in the demodulation process.

In this embodiment, this reproducing system
Even after the operation is switched in this way, the digital video signal in the demodulation process is continuously subjected to demodulation processing and output from the decoder 4G. Further, the output of the digital video signal in the demodulation process to the external device is stopped, and the digital video signal is recorded in the reproduction memory 5 together with the previous AV signal.

That is, in the video tape recorder 1 (FIG. 2), the reproduction memory 5 is adapted to record AV signals for a predetermined frame, and switches the operation under the control of the reproduction memory control circuit 11. The reproduction memory 5 sequentially and cyclically switches the recording area, and stores the digital video signal DV output from the reproduction signal processing circuit 4 and the corresponding digital audio signal. Accordingly, when the magnetic tape is continuously reproduced at, for example, 1 × speed, the reproduction memory 5 sequentially updates the held contents and goes up from the AV signal to be transmitted to the external device to the AV signal corresponding to the capacity. Hold.

For a predetermined period after the operation mode of the video tape recorder 1 is switched, the held AV signal is output to an external device instead of the output of the reproduction signal processing circuit 4.

The reproduction memory control circuit 11 switches the operation of the reproduction memory 5 under the control of the tape running control circuit 9. Further, it monitors the data amount D4 of the AV signal held in the reproduction memory 5 and notifies the tape running control circuit 9 whether or not this data amount is equal to or more than a predetermined value.

In the video tape recorder 1 (FIG. 2), a tape position detector 6 obtains a reproduction signal of a control track formed in the longitudinal direction of the magnetic tape 2 via a predetermined fixed head 7, and converts this reproduction signal. Demodulate the magnetic head 3
And detects and outputs the position information D3 corresponding to the scanning position.

The magnetic tape drive circuit 8 outputs drive signals for the reel motor, the capstan motor 10 and the like under the control of the tape running control circuit 9, thereby causing the magnetic tape 2 to run at a predetermined running speed.

The system control circuit 12 is composed of a computer for controlling the operation of the entire video tape recorder 1. The system control circuit 12 controls the tape running control circuit 9, the reproduction signal processing circuit 4 and the like in response to the operation of the controls and the jog dial. A command CD is issued, whereby the entire operation mode is switched in response to the operation of the operator.

The tape running control circuit 9 controls the operations of the reproduction memory control circuit 11 and the magnetic tape drive circuit 8 in response to a control command output from the system control circuit 12. At this time, the tape running control circuit 9 switches the overall control according to the position information D3 detected by the tape position detector 6 and the notification of the data amount D4 of the reproduction memory 5 notified by the reproduction memory control circuit 11.

FIG. 1 is a flowchart for explaining the control in the tape running control circuit 9. When a control command is input from the system control circuit 12, the tape running control circuit 9 executes this processing procedure.

That is, for example, when the jog dial is operated by the operator in the still state and the reproduction of the magnetic tape 2 is instructed in the still state, the tape running control circuit 9 responds to the control command output from the system control circuit 12 from step SP1. In step SP2, it is determined whether or not an AV signal of a predetermined data amount is stored in the reproduction memory 5 based on the notification from the reproduction memory control circuit 11.

Here, the predetermined amount of data is
During the period from the start of reproduction to the time when the corresponding AV signal is demodulated and can be output to the monitor device, the AV signal held in the reproduction memory 5 is output, and the AV signal is output to the monitor device without interruption. This is the minimum amount of data that can be performed.

More specifically, this data amount is determined by rapidly forwarding the magnetic tape by the number of frames obtained by adding a predetermined number of frames to the process delay in the forward direction, the process delay in the reverse direction, and the number of frames corresponding to the sum of these process delays. Is the data amount of the AV signal corresponding to the sum time obtained by adding the transition time α.

In these cases, even when the reproduction direction is switched without the still state, the data amount of the judgment criterion in step SP2 is the same as that in the case of once passing through the still state.

That is, as shown in FIG. 6, assuming that the process delay in the forward direction is 5 frames, in this embodiment, even after the operation is switched, the digital video signal in the demodulation process is continuously demodulated. When the running of the magnetic tape 2 is stopped at the timing when the 0 frame is displayed on the monitor by sequentially and cyclically recording the AV signal in the reproduction memory 5, It stops at the position preceding by the delay (FIG. 6 (A)).
In this case, in the reproduction memory 5, the AV signals in the reproduction process are accumulated, so that the AV signals of the amount (process delay) preceding the magnetic tape 2 from the 0 frame are accumulated and held.

As a result, the reproduction is resumed from the stop position of the magnetic tape 2 and the AV signal reproduced from the magnetic tape 2 with a delay corresponding to the process delay can be output to the monitor device. By sequentially transmitting the AV signals stored in the reproduction memory 5, continuous AV signals can be output without interruption (FIG. 6).
(C)). That is, the operation of the magnetic tape traveling system is controlled so that the scanning position of the magnetic head 3 precedes the AV signal output to the monitor device by the process delay.
The V signal can be output without interruption.

Similarly, assuming that the process delay in the reverse direction is five frames, as shown in FIG. 7, after normal reproduction is continued in the reverse direction and set to the still state, normal reproduction is performed in the reverse direction. Similarly,
After setting to the still state, the AV signal in the demodulation process is stored in the reproduction memory, and immediately after the reproduction in the reverse direction is resumed, the stored AV signal is output to the monitor device, so that the AV signal continuous from the still state is output. Can be output without interruption (FIG. 7A)
(C)). That is, also in this case, the operation of the magnetic tape traveling system is controlled so that the scanning position of the magnetic head 3 precedes the AV signal output to the monitor device by the process delay, and the AV signal continuous from the still state is output. It can output without interruption.

Further, as shown in FIG. 8 in comparison with FIGS. 6 and 7, after normal reproduction is continued in the forward direction and set to the still state, the reproduction direction is reversed and normal reproduction is started in the reverse direction. In this case, in the still state, the magnetic tape 2 stops at a position preceding by the process delay (FIG. 8A). In this case, the reproduction memory 5 accumulates and holds the past AV signal from the 0 frame in which the running of the magnetic tape 2 is controlled to stop by subtracting the process delay from the capacity of the reproduction memory 5 (FIG. 8). (B-1)).

Immediately after the reproduction direction is reversed and the reproduction of the magnetic tape 2 is started, the past AV signals from the 0 frame held in the reproduction memory 5 are sequentially outputted, and the past AV signals held in the reproduction memory 5 are sequentially outputted. During the period until the signal output is completed, the magnetic tape 2 is fast-forwarded in the reverse direction, and the AV signal of the frame (in this case, −15 frame) subsequent to the oldest frame stored in the reproduction memory 5 is monitored. If it is possible to output to
(B-2) and (C)), continuous A from the still state
The V signal can be output without interruption.

In the case where normal playback is continued in the reverse direction and the still state is set, and then the playback direction is reversed and normal playback is started in the forward direction, similarly, continuous AV signals from the still state are interrupted. Can be output without the need.

That is, when the reproduction direction is reversed in this way, the reproduction memory 5 is added to the process delay in both directions by adding the transition time α required for fast-forwarding the magnetic tape 2.
If the AV signal is stored in the memory, a continuous image can be output without interruption.

Thus, even when the reproduction direction is reversed,
Assuming that a predetermined amount of data is held in the reproduction memory 5, the AV signal output to the monitor device is
By controlling the operation of the magnetic tape traveling system so that the scanning position of the magnetic head 3 is advanced by the process delay, an AV signal continuous from the still state can be output without interruption.

According to this control principle, the tape running control circuit 9 proceeds from step SP2 to step SP3 when the data amount corresponding to the control command is held in the reproduction memory 5 by the notification from the reproduction memory control circuit 11. As described above with reference to FIGS. 6 to 8, the overall operation is controlled so that the scanning position of the magnetic head 3 precedes the AV signal output to the monitor device by the process delay. That is, by issuing a control command to the magnetic tape drive circuit 8 according to the position information detected by the tape position detector 6 and controlling the operation of the reproduction memory 5 via the reproduction memory control circuit 11, the tape travel control circuit 9
Outputs a continuous AV signal to the monitor device without interruption. Further, when a control command is issued to the magnetic tape drive circuit 8 and the reproduction memory control circuit 11, the process proceeds to step SP4, and this processing procedure is ended.

On the other hand, if the reproduction memory 5 does not store a certain amount of data, the tape running control circuit 9
Moves to step SP5 when a negative result is obtained in step SP2. Here, for example, when a control command for stopping the reproduction of the magnetic tape 2 is input, the tape running control circuit 9 stops the running of the magnetic tape 2 and then responds to the AV signal output to the monitor device by the magnetic head 3. The operation of the tape traveling system is controlled by displacing the magnetic tape in the reverse direction by an amount substantially equal to the preceding scanning (that is, approximately the process delay) so that the tape position becomes substantially equal to the image output position.

In response to a command such as reproduction, the running of the magnetic tape 2 is started from the position at which the magnetic tape is fast-forwarded in this manner, so that the tape running system is operated so that the tape position becomes substantially equal to the image output position. While the operation is being controlled, the operation of the magnetic tape traveling system and the like is controlled so as to correspond to the control command.

That is, when the data amount described above is not stored in the reproduction memory 5, even if the operation of the magnetic tape traveling system and the reproduction memory 5 is controlled as described above with reference to FIGS. Output becomes difficult.

For example, when the jog dial is operated after fast-forwarding and setting the still state, the reproduction memory 5 is kept in a state where a sufficient amount of data is not stored. In this case, after the magnetic tape 2 is reproduced in the forward direction by operating the jog dial for a few frames and then the reproduction in the reverse direction is started, after the jog dial is operated, the process delay in the forward direction and the process delay in the reverse direction are delayed. The corresponding video is displayed on the monitor device. In this case, the delay time becomes extremely long, and the usability deteriorates remarkably.

In this case, as shown in FIG.
Is stopped, so that the position of the magnetic head 3 on the magnetic tape 2 matches the last video output.
When the magnetic tape 2 is run (FIGS. 9A and 9B), after the reproduction is started in the forward direction, the image changes on the monitor device with a delay corresponding to the process delay in the forward direction. (Fig. 9
(C) and (D)).

On the contrary, after the reproduction is started in the reverse direction, the image changes on the monitor device with a delay corresponding to the process delay in the reverse direction (FIG. 9 (E)). And (F)). In FIG. 9, the process delay in the reverse direction and the forward direction is described as five frames.

Further, in these cases, when the running of the magnetic tape 2 is subsequently stopped, the magnetic tape 2 is moved so that the position of the magnetic head 3 on the magnetic tape 2 coincides with the last video output. Accordingly, even when the magnetic tape 2 is reproduced in the reverse direction and the forward direction by switching the direction thereafter, the image of the monitor device is changed by delaying by the process delay in the reverse direction and the forward direction, respectively. Become. As a result, after the jog dial is operated, the waiting time until the image actually changes can be reduced, the accessibility is improved,
Usability is improved.

Further, in these cases, the AV signal is stored in the reproduction memory 5 at least for the process delay corresponding to the reproduction direction, so that, for example, when the jog dial is operated, the reproduction direction is changed once in the reverse direction and once in the forward direction. Or the magnetic tape 2 is reproduced by the number of frames corresponding to the data amount described in step SP2, and the subsequent reproduction of the magnetic tape 2 by operating the jog dial starts from step SP2.
By the processing procedure of 2-SP3, it is possible to effectively avoid the generation of the delay time due to the process delay.

More specifically, in this embodiment, when the reproduction of the magnetic tape 2 is stopped, the magnetic tape is displaced to a predetermined standby position, whereby the tape traveling system is moved so that the tape position becomes substantially equal to the image output position. Control the operation of.

Here, when the tape running control circuit 9 stops the running of the magnetic tape 2 by fast-forwarding in the forward direction, the tape is temporarily reproduced at 1 × speed to stop the running of the magnetic tape 2. After fast-forwarding in the forward direction as described above, the position that is two frames ahead of the last frame of the digital video signal output by reproduction at the 1 × speed is set as the standby position.

Similarly, when the tape running control circuit 9 stops the running of the magnetic tape 2 by fast-forwarding in the reverse direction, the tape running control circuit 9 once reproduces the magnetic tape 2 at 1 × speed and stops the running of the magnetic tape 2. After fast-forwarding in the reverse direction as described above, a position two frames later than the last frame of the digital video signal output by the reproduction at the 1 × speed is set as the standby position. Thereby, the tape running control circuit 9
Is designed to reduce the number of rewinds to the standby position.

FIG. 10 is a transition state diagram for explaining the operation of the video tape recorder 1 when the magnetic tape 2 is stopped by fast-forwarding in the forward direction.

When the operator instructs to stop fast-forwarding in the fast-forwarding state, the tape running control circuit 9 causes the magnetic tape 2 to run at the normal playback speed of 1 × for a period of eight frames. Thereafter, the running of the magnetic tape 2 is controlled to be stopped (FIG. 10A). Reproduction signal processing circuit 4
In the case of (1), the compressed video signal (FIG. 10 (C)) input to the outer code error correction circuit 4D with respect to the reproduction signal RF (FIG. 10 (B)) obtained from the magnetic head 3 at the time of fast forward.
Is further delayed by three frames, and the compressed video signal subjected to error correction processing by the outer code error correction circuit 4D is further delayed by three frames by the packing circuit 4E. (FIGS. 10 (D) and (E)), and are output after being delayed by three frames in the decoder 4G following the unpacking circuit 4F (FIG. 1).
0 (F) and (G)).

In this state, in the reproduction signal processing circuit 4, for the four frames immediately after the switching to the 1 × speed (the frames indicated by hatching in FIG. 10),
The error correction process in the outer code error correction circuit 4D is stopped and controlled, thereby effectively avoiding error correction. One more
As for the sixth frame immediately after the switching to the double speed, the packing circuit 4E further forms a time delay of two frames (the frame indicated by the broken line in FIG. 10). By forming such a delay time, in the reproduction signal processing circuit 4, when the traveling of the magnetic tape 2 is stopped,
The demodulation process is continuously executed for the digital video signal in the reproducing process, and the output to the monitor device is stopped only for the digital video signal for the last two frames.

Thus, in the reproduction signal processing circuit 4, when the traveling of the magnetic tape 2 is stopped from the fast-forward, the stop of the fast-forward can be visually confirmed by a change in an image corresponding to the traveling speed of the magnetic tape 2. An AV signal is output to a monitor device. Thus, when the running of the magnetic tape 2 is stopped, the magnetic tape is held at a position two frames ahead of the last frame of the digital video signal output by the reproduction at 1 × speed.

Also, in the case of reverse reproduction, the magnetic tape is held at a position two frames ahead of the frame of the digital video signal output last by reproduction at -1.times. Speed. .

In the above-described configuration, in the video tape recorder 1 (FIG. 2), a video signal sequentially inputted is such that consecutive frames are alternately set to I-pictures and B-pictures (FIG. 3), and data is output in MPEG format. After compression, an error correction code in a product code format is added and shuffling is performed, and then time-division multiplexed with a digital audio signal and recorded on a magnetic tape.

On the other hand, at the time of reproduction, after the demodulated data D1 is demodulated from the reproduced signal RF obtained from the magnetic head 3, the digital video signal is demodulated by a process reverse to that at the time of recording (FIG. 4). The digital video signal is output to the monitor device as an AV signal together with the corresponding digital audio signal, and is output to an external device through a predetermined serial interface (SDDI).

At this time, the digital video signal undergoes processing such as deshuffling processing and data decompression processing, so that the reproduction signal RF output from the magnetic head 3 is processed over a period of a plurality of frames, and In standard reproduction in the forward direction, the plurality of frames are output by a process delay including 9 frames, and in standard reproduction in the reverse direction, the plurality of frames are output by a process delay including 15 frames. Further, when the reproduction of the magnetic tape 2 is stopped, 9
This means that the magnetic head 3 has scanned the position preceding the frame and the 15th frame (FIG. 5).

In this series of processing, when the reproduction of the magnetic tape 2 is stopped, when the running of the magnetic tape 2 is stopped, the reproduction signals RF for these 9 frames or 15 frames in the reproduction process are continuously processed. As a result, a digital video signal corresponding to the preceding scanning of the magnetic head 3 is reproduced together with the digital audio signal.

Further, the digital video signal output to the monitor device is stored together with the corresponding audio signal in the reproduction memory 5 in which the recording area is sequentially and cyclically switched, whereby the digital video signal corresponding to the preceding scanning is obtained. And the digital audio signal are recorded and held in the reproduction memory 5 together with the past digital video signal and digital audio signal.

When, for example, the operator operates the jog dial to instruct reproduction of the magnetic tape 2, the tape traveling control circuit 9 controls the AV held in the reproduction memory 5.
The data amount of the signal is confirmed (FIG. 1). If the data amount is sufficient, the entire operation is controlled so that the magnetic head 3 scans ahead by the process delay. Even if the process delay corresponds to a plurality of frames, the continuous digital video signal and digital audio signal can be monitored by the monitor device without making the operator aware of the process delay even if the process delay corresponds to a plurality of frames. Is output to

That is, when the reproduction in the forward direction is continued (FIG. 6), the reproduction of the magnetic tape 2 is started from the position preceding by the process delay and the reproduction memory 5
After the reproduction is started by sequentially outputting the AV signals held in the reproduction memory 20 by the process delay stored in the reproduction memory 20 to the digital video signal delayed by the process delay during the period from the start of reproduction, A video continuous from the video whose reproduction has been stopped is displayed on the monitor device. When the demodulated digital video signal delayed by the process delay can be output to the monitor device, the reproduced AV signal is output in place of the AV signal in the reproduction memory 5, and the continuous video is output to the monitor device. Displayed above.

When the reproduction in the reverse direction is continuous (FIG. 7), the output of the continuous AV signal is possible by controlling the operation of the reproduction memory 5 while controlling the magnetic tape traveling system. . When the reproduction is performed with the direction switched (FIG. 8), immediately after the start of the reproduction, the process delay on the forward side and the reverse side and the transition time α required for fast-forwarding the magnetic tape 2 are added.
, In the playback direction, and then playback of the magnetic tape 2 is started. Also, until the reproduction of the magnetic tape 2 is started and the AV signal delayed by the process delay can be output, the AV signal held in the reproduction memory 5 is output, whereby a continuous image is displayed on the monitor device. Is done.

In addition to the repetition of such reproduction processing, the video tape recorder 1 may perform fast-forward and rewind reproduction. After such fast-forward and rewind reproduction, the AV The signal is not being held. In this case, even if the reproduction process is subsequently started, continuous video cannot be displayed depending on the AV signal held in the reproduction memory 5. In this case, for example, by operating the jog dial and performing the same processing for the operation of repeating the reproduction in which the direction is switched in a very short time, the image on the monitor device is interrupted on the way, and an unnatural image is rather formed. Will be displayed. If, on the other hand, you do not perform any such control,
At the time of switching the reproduction direction, a desired image is not displayed for an extremely long period of time when the process delay in the forward direction is added to the process delay in the forward direction.

In this video tape recorder 1, when the magnetic tape is stopped and controlled by the fast-forward and rewind reproductions, the magnetic tape 2 is reproduced at 1x speed and -1x speed for a predetermined period, and then the running of the magnetic tape 2 is started. Stop control is performed. Accordingly, in these cases, in a state where the running of the magnetic tape 2 is stopped, A corresponding to the stop of the fast forward and the rewind reproduction respectively.
The magnetic head 3 scans a portion preceding each of the V signals by two frames (FIG. 10).

In the video tape recorder 1, the position of the magnetic tape 2 with respect to the AV signal is defined as a standby position.
If the reproduction memory 5 does not hold a sufficient amount of data, the magnetic tape 2 is stopped after traveling so that the positional relationship of the magnetic tape 2 with respect to the AV signal output last during reproduction becomes the standby position. The tape 2 is displaced.

As a result, in the video tape recorder 1,
The operation of the tape running system is controlled so that the tape position is substantially equal to the image output position. In the subsequent reproduction (FIG. 9), the AV signal is output with a delay from the standby position by a process delay in each direction. Will be done. As a result, a state in which a desired image is not displayed for a very long period of time, and a state in which an image changes unnaturally can be effectively avoided, thereby improving the accessibility and the usability.

Further, since the standby position is the stop position of the magnetic tape 2 in the fast-forward and rewind, the magnetic tape 2 is moved to the standby position after the fast-forward and rewind.
For example, when the magnetic tape is fast-forwarded and rewound by a shuttle mode frequently used in editing work, and then immediately reproduced from the magnetic tape, the waiting time can be reduced.

Thus, in the control for displacing the magnetic tape to such a standby position, if the magnetic tape is reproduced by repeating the reproduction of the magnetic tape 2 or subtracting the process delay from the capacity of the reproduction memory 5, By accumulating a sufficient amount of data in the reproduction memory 5, in the subsequent reproduction processing, the entire operation is controlled so that the scanning of the magnetic head 3 precedes the process delay, so that the process delay is not made conscious of the operator. To execute the editing process.

According to the above configuration, after the reproduction of the magnetic tape 2 is stopped, the magnetic tape is displaced to the standby position so that the video output and the position of the magnetic tape 2 substantially coincide with each other. Even when a sufficient amount of data is not accumulated, the video signal can be output with a delay corresponding to the process delay when the subsequent reproduction process is executed by switching the reproduction direction. Thereby, accessibility can be improved and usability can be improved.

By setting this standby position at the position where the magnetic tape is fast-forwarded, rewound and stopped, the waiting time is reduced when the magnetic tape 2 is reproduced immediately after fast-forwarding and rewinding, and the magnetic tape is displaced. It is possible to reduce the number of times to perform.

Further, after a sufficient amount of data has been stored in the reproduction memory 5, the tape running system is controlled so as to precede the process delay by an amount corresponding to the process delay. By supplementing the time, an image desired by the operator can be provided immediately following the operation of the jog dial or the like, thereby improving the usability.

In the above embodiment, the case where the position where the magnetic tape is fast-forwarded, rewound, and stopped is set as the standby position has been described. However, the present invention is not limited to this. For example, the process delay in the forward direction may be set. The standby position may be set to an intermediate position between the minute and the process delay in the reverse direction.Furthermore, according to the characteristics of the magnetic tape traveling system, the digital video signal at the time when the reproduction of the magnetic tape is stopped is determined. By setting the standby position at a position equal to or less than the process delay, the standby time when the reproduction direction is switched can be reduced.

In the above-described embodiment, when the digital video signal is stored in the reproduction memory by the amount of the process delay in the forward direction and the reverse direction plus the transition time α due to the fast forward, the magnetic tape running system However, the present invention is not limited to this, and the capacity of the reproduction memory is further reduced as long as continuous video disturbance can be sufficiently tolerated in practice. The control of the tape running system may be switched according to the following data amount, and in a simple configuration in which the reproduction memory is omitted, the control may be performed only to set the tape at the standby position.

In the above-described embodiment, the case where the present invention is applied to a video tape recorder having a process delay of 9 frames and 15 frames in the forward direction and the reverse direction, respectively, has been described. However, the present invention is not limited to this. However, the present invention can be widely applied to a video tape recorder that requires a period of a plurality of frames of a video signal and processes a reproduction signal obtained from a magnetic head to reproduce a video signal.

[0082]

As described above, according to the present invention, the present invention provides a method for stopping reproduction of a magnetic tape in a process delay until a video signal is demodulated from a reproduction signal output from a magnetic head. By setting the magnetic tape at a predetermined standby position for the video signal output last below the range of the process delay, the standby time when switching the playback direction and starting playback is reduced, thereby improving usability. be able to.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining the operation of a tape running control circuit of a video tape recorder according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an overall configuration of the video tape recorder of FIG.

FIG. 3 is a schematic diagram illustrating setting of pictures in the video tape recorder of FIG. 2;

FIG. 4 is a block diagram showing a reproduction signal processing circuit of the video tape recorder of FIG. 2;

FIG. 5 is a state transition diagram for explaining processing of a reproduction signal during normal reproduction in the forward direction.

FIG. 6 is a schematic diagram for explaining control of a magnetic tape traveling system and a reproduction memory during standard reproduction in a forward direction.

FIG. 7 is a schematic diagram for describing control of a magnetic tape traveling system and a reproduction memory during standard reproduction in a reverse direction.

FIG. 8 is a schematic diagram for explaining control of a magnetic tape traveling system and a reproduction memory when a reproduction direction is switched from a forward direction to a reverse direction.

FIG. 9 is a schematic diagram for explaining a magnetic tape traveling system when sufficient data is not stored in a reproduction memory;

FIG. 10 is a state transition diagram for explaining a standby position.

[Explanation of symbols]

1. Video tape recorder 2. Magnetic tape 3.
... magnetic head, 4 ... reproduction signal processing circuit, 5 ... reproduction memory, 6 ... tape position detector, 9 ... tape running control circuit, 11 ... reproduction memory control circuit

Claims (7)

[Claims] 1. A video tape recorder for reproducing and outputting a video signal recorded on a magnetic tape, the signal processing being performed on a reproduction signal output from a magnetic head in a period of a plurality of frames of the video signal. A reproduction signal processing circuit that outputs the video signal, and a position detection unit that detects a relative position of the magnetic tape with respect to the magnetic head and outputs a position detection result. Magnetic tape travel control means for moving the magnetic tape relative to the magnetic head to displace the magnetic tape, wherein the magnetic tape travel control means stops the reproduction of the magnetic tape, and then stops the magnetic tape at a predetermined standby position. Displacing the tape, the standby position, the video signal at the time of stopping the reproduction of the magnetic tape, the magnetic tape of the A video tape recorder, wherein a position is a position of the plurality of frames or less. 2. The standby position, wherein the position of the magnetic tape substantially corresponds to the video signal output from the reproduction signal processing circuit when reproduction of the magnetic tape is stopped. The video tape recorder according to claim 1, wherein: 3. The magnetic tape running control means and the reproducing means, when stopping fast-forward reproduction of the magnetic tape, temporarily reproduce the magnetic tape at a standard reproducing speed to stop the running of the magnetic tape. When stopping the running of the magnetic tape from the playback at the standard playback speed, after stopping the running of the magnetic tape, processing at least a part of the playback signal in the process of processing and outputting the video signal The video tape recorder according to claim 1, wherein the standby position is a position where the magnetic tape is stopped. 4. A video signal recording unit having a predetermined capacity for recording the video signal, wherein the reproduction signal processing unit processes the reproduction signal in a processing process after stopping the running of the magnetic tape. The video signal recording means sequentially records the video signal output from the reproduction signal processing means cyclically, and after starting reproduction of the magnetic tape, During the period until the output of the video signal from the reproduction processing means is started,
2. The video tape recorder according to claim 1, wherein the video signal held is output. 5. The magnetic tape running control means according to the amount of data held in the video signal recording means,
5. The magnetic tape according to claim 4, wherein the displacement of the magnetic tape to the standby position is stopped, and the magnetic tape is caused to travel such that the traveling of the magnetic tape precedes the video signal for the plurality of frames. The video tape recorder described in 1. 6. A video tape recorder for reproducing and outputting a video signal recorded on a magnetic tape, the signal processing being performed on a reproduction signal output from a magnetic head in a period of a plurality of frames of the video signal. Outputting the video signal, stopping the reproduction of the video signal, and then displacing the magnetic tape in a direction opposite to a reproduction direction of the video signal by an amount corresponding to the plurality of frames. Recorder. 7. The video signal storing the video signal in a predetermined video signal recording means, and starting reproducing the magnetic tape, and then recording the video signals corresponding to the plurality of frames in the video signal recording means. When the data amount of the video signal held in the video signal recording unit is equal to or more than a predetermined value, the displacement of the magnetic tape to the standby position is stopped, and the plurality of frames, the video signal is compared with the video signal. 7. The video tape recorder according to claim 6, wherein the magnetic tape is caused to travel so that the magnetic tape travels first.