JPH1013782A - Reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To receive all still image data in the case of reproducing a tape with e.g. 5-frames of still image data recorded thereon at a tape speed slower than the usual speed in the high compression mode (SLD mode) in succession to image data recorded at a usual tape speed in the usual mode (SP mode) in a digital VTR. SOLUTION: In the state of reproduction in the SDL mode at a tape speed half the usual tape speed, when an ATF error is small in the step S1, phase servo and speed servo control is conducted as it is in the step S2. When the ATF error is high, the mode is detected in the step S3 and when the SP mode is transited, a moving image/still image is detected in the step S4, and in the case of a still image, the still image is processed in the step S9 and the tape speed is set to be a half in the SLD mode in the step S10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing apparatus which has a normal mode and a high compression mode and is suitable for use in a helical scan type digital VTR for recording and reproducing moving images and still images.

[0002]

2. Description of the Related Art The format of a digital VTR determined by the Consumer Digital VTR Council has a normal mode (hereinafter referred to as SP mode) and a high compression mode (hereinafter referred to as SDL mode), and records and reproduces moving images and still images. Each of the modes can be performed in the above two modes.
In the SDL mode, the data amount is compressed to 1/2 and the tape speed is 1/2 in the SP mode. Also SP
Assuming that the number of tracks constituting one frame in the mode is n, the number in the SDL mode is n / 2.

There are two still image recording methods, one of which is to record the same image continuously for 5 frames, and the other is to record the same image for a predetermined period (for example, 5 to 6 seconds). ) It is a method of recording continuously.

[0004] The SP mode and the SDL mode can be switched for one tape, so that a moving image or still image in the SP mode and a moving image or still image in the SDL mode are mixed on one tape. May be recorded.

FIG. 6 shows a schematic configuration of a reproducing section of a conventional digital VTR having the above two modes. 6, reference numeral 20 denotes a magnetic tape; 21, a reproducing head; 22, a signal processing unit that performs processing such as A / D conversion and demodulation on a reproduced signal obtained from the reproducing head 21 and outputs a video signal;
Is an ATF circuit for extracting a tracking error signal from the reproduction signal, 24 is a capstan motor for running the tape 20, and 25 is a signal processing unit 22 which switches processing in SP or SDL mode according to the tracking error signal. , A microcomputer for controlling the speed of the capstan motor 24.

FIG. 7 is a flow chart showing the operation of the microcomputer 25 when the tape 20 in which the SP mode image and the SDL mode image are mixed is reproduced by the digital VTR having the above configuration. This flowchart is started by an interrupt command given from the outside of the microcomputer 25 for a predetermined period.

In FIG. 7, when there is an interrupt command, the microcomputer 25 first determines the error value indicated by the tracking error signal output from the ATF circuit 23 in step S101, and if the error value is smaller than the predetermined value, the process proceeds to step S10.
After resetting the counter in step 2, the process ends. If the error value is larger than the predetermined value, the counter is incremented in step S103. In step S104, the counter value is checked. If the counter value exceeds a predetermined value, step S104 is executed.
At 105, the counter is reset. Next, step S10
In step 6, the current mode is checked. If the current mode is the SP mode, the mode shifts to the SDL mode in step S107. If the current mode is the SDL mode, the mode shifts to the SP mode in step S107.

As described above, when the tracking error from the ATF circuit 23 is large, the SP and the SDL
Are repeated to lock in the SP mode or the SDL mode when the tracking error from the ATF circuit 23 becomes small.

[0009]

However, in the above conventional example, the SP mode and the SDL mode are repeated at regular intervals, and when the error value from the ATF circuit becomes small, the SP or SDL mode is determined. There were the following problems.

(1) When reproducing a part in which still images of five frames are recorded as a still camera in the SP mode, starting from the part recorded in the SDL mode on the tape, the SDL
It takes time to shift from the mode to the SP mode, so that still image data for 5 frames may not be obtained.

(2) Even if the mode is shifted to the SP mode within five frames, an error may have occurred in the still picture data because the mode has just been switched.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to solve the problem described above when a still image of five frames in SP mode recorded as a still camera is recorded in the middle of a moving image in SDL mode. It is to ensure that still image data can be captured.

Another object of the present invention is to enable a frame having the best condition among the captured five frames of still image data to be handled as still image data.

[0014]

According to the present invention, there is provided a reproducing apparatus for conveying a tape-shaped recording medium on which a large number of oblique tracks are formed and reproducing image data, wherein the recording mode of the reproduced image data is as described above. A first mode in which the tape-shaped recording medium is transported at a normal speed to record the image data, or a second mode in which the tape-shaped recording medium is transported at a speed lower than the normal speed to record the image data Mode detecting means for detecting whether the image indicated by the reproduced image data is a moving image or a still image; and Control means for controlling the transport speed of the tape-shaped recording medium.

[0015]

According to the present invention, the recording in the first mode such as the SP mode is detected while the high-compression image data is being reproduced while the recording medium is being sent at a low speed in the second mode such as the SDL mode. If it is detected that the reproduced image in the first mode is a still image, the reproduction is performed while the feed speed is not changed to the normal speed but is fed at the slow speed in the second mode. Thereby, all the still image data can be captured.

[0016]

FIG. 1 is a diagram showing a configuration of a reproducing unit of a helical scan type digital VTR according to an embodiment of the present invention. In FIG. 1, 1 is a magnetic tape on which a digital video signal is recorded, 2 is a magnetic head that reproduces a video signal recorded on the magnetic tape 1 and converts it into an electric signal, and 3 is reproduced by a magnetic head 2 An A / D converter for converting a reproduction signal into digital image data;
The track memory 5 stores the digital data from the / D converter 3 for one track, the digital memory 5 reads the digital data stored in the track memory 4, checks the inner parity (Inner Parity) of each sync block, and detects an error. An error correction circuit 6 performs a frame memory for storing one frame of compressed image data when there is no error. Reference numeral 7 denotes a decompression circuit for extracting and decompressing one frame of compressed image data from the frame memory 6, 8 a frame memory for storing image data output from the decompression circuit 7, and 9 an image data from the frame memory 8. D to convert to analog signal and output
/ A converter.

Reference numeral 10 denotes an ATF circuit for extracting a tracking error signal from digital data extracted from the A / D converter 3, and reference numerals 10 and 11 denote outer parities (Outer Parities) in one frame of image data.
y) an error correction circuit for performing error detection by checking
Reference numeral 12 denotes a capstan motor for moving the magnetic tape 1 in accordance with an instruction from the microcomputer 13, and reference numeral 13 denotes a microcomputer for controlling each circuit based on information from each circuit.

FIG. 2 shows a track format on the magnetic tape 1. Normal mode (SP mode) and high compression mode (SDL mode)
In the SDL mode, the data amount is compressed to half of that in the SP mode, the tape speed is 1/2, and one frame is composed of n / 2 tracks (n is one frame in the SP mode). Tracks) Here, as shown in FIG. 2, the SP mode and the SDL mode are recorded on the magnetic tape 1 in a mixed manner.

FIG. 3 shows the data structure in one track formed on the tape 1. In FIG. 3, data for one track is composed of 1 to m sync blocks (SyncB).
lock). Each of the sync blocks 1 to i includes an ID, video data, and inner parity. The sync blocks i + 1 to m are composed of ID, outer parity, and inner parity.

The inner parity is provided in every sync block and is used for detecting a horizontal error in the sync block. Outer parity is used for error detection in the vertical direction. In addition, the sync block No. is included in the ID. (1
To m), an SP / SDL mode determination flag, and a moving image / still image determination flag.

FIG. 4 shows a case where the tape 1 in which the SP and SDL modes are mixed as shown in FIG.
6 is a flowchart illustrating an operation of shifting from a mode to an SP mode.

First, in the SDL mode, the tape speed is S
Image data composed of 1/2 track and n / 2 tracks per frame in the P mode is sequentially reproduced, and the circuits 3 to 9 in FIG. 1 perform processing such as error correction, decompression, and D / A conversion. Then, an analog image signal is output.

When the recording area of the SP mode is entered from the SDL mode, the microcomputer 13 first compares the tracking error signal for ATF output from the ATF circuit 10 in step S1 with a predetermined value. If it is smaller, the current SDL mode is determined, and the phase servo and velocity servo processes are executed using the tracking error signal in step S2, and the result is fed back to the capstan motor 12.

If the tracking error signal output from the ATF circuit 10 is larger than a predetermined value, step S3
In the digital data written in the track memory 4, the inner parity added to each sync block is checked by the error correction circuit 5, and an error-free sync block is written to the frame memory 6, and at the same time, Is sent to the microcomputer 13. The microcomputer 13 uses the ID information sent from the error correction circuit 5
Determine the P / SDL mode.

As a result, if it is determined that the mode is the SDL mode, the tape speed is reduced to half of that in the SP mode in step S4, and then the capstan motor 1 is switched in step S5.
In step S2, phase servo and speed servo processing are executed and the speed error is fed back to the capstan motor 12. If the speed error is large, a speed servo process is executed in step S 6, and the speed servo process is fed back to the capstan motor 12.

As a result of the SP / SDL determination in step S3, if it is determined that the mode is the SP mode, the moving image / still image flag included in the ID information is determined in step S7. In the case of a moving image, the tape feed speed of the capstan motor 12 is set to 1 × speed, that is, the speed in the SP mode in step S8, and speed servo processing is executed in steps S5 and S6 to feed back to the capstan motor 12. If the moving image / still image flag is a still image, step S
In step S10, the still image processing is executed. In step S10, the tape feed speed is set to 1/2 times the speed in the SP mode. In step S6, the speed servo process is executed, and the tape feed back to the capstan motor 12. As a result, the portion of the tape 1 where the still image is recorded in the SP mode is set to the tape speed SP.
As a half of the mode, a track for one frame is traced and reproduced over a period of two frames. The reproduced still image data having no error in the inner parity is written in the frame memory 6.

As described above, when a still image is recorded in the SP mode, the tape speed is kept at １ ／ of that in the SP mode, even if the immediately preceding reproduction mode is the SDL mode. Each track recorded in the SP mode is traced twice. Therefore, although it takes twice as long as when reproducing in the SP mode to reproduce a still image for one frame, disturbance of the reproduced image due to mode switching can be suppressed to an extremely small level.

FIG. 5 shows a flowchart of the still image processing in step S9. First, the microcomputer 13 sends a still image mode signal to the error correction circuit 11 in step S11. The error correction circuit 11 checks the outer data quality of the video data for each track of the frame memory 6 in which digital data for n tracks is present, and detects the presence or absence of an error in the frame memory 6.
Send the result to 3.

If there is error data in the frame memory 6, the microcomputer 13 requests the decompression circuit 7 to stop the processing in step S13 and prohibits writing to the frame memory 8. The D / A converter 9 converts the frozen image data of the frame memory 8 into an analog image signal and outputs it.

When there is no error in the frame memory 6, it is determined that one frame of still image data is present in the frame memory 6, and the writing to the frame memory 6 by the error correction circuit 5 is prohibited. At the same time, the expansion circuit 7
Is requested to be expanded in the SP mode. The still image data expanded in the SP mode is written in the frame memory 8, and a still image signal is output via the D / A converter 9.

As described above, according to the present embodiment, S
When still image data like a still camera of the first mode such as the SP mode exists in the middle of the second mode such as the DL mode, by reproducing this still image portion at the speed of the second mode, Short recording period (for example, 5 frames)
All of the still image data can be captured. In addition, still image data having a long recording period can be captured faster.

Further, by reproducing still image data in the first mode at the speed of the second mode and evaluating the still image data using, for example, inner / outer parity, it is determined whether all the still image data are present. Can be accurately recognized. The above evaluation can be applied to portions other than the connection portion of each mode on the recording medium.

[0033]

As described above, according to the present invention,
Since the transport speed of the recording medium is controlled according to the recording mode of the reproduced image data and the image indicated by the reproduced image data, it is possible to optimally control the transport speed according to the content of the image data in the recording mode. . For example, it is possible to prevent the reproduced image from being disturbed at the switching portion of the recording mode due to the difference in the transport speed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a track format on a magnetic tape.

FIG. 3 is a diagram showing a data structure in one track.

FIG. 4 is a flowchart showing the entire operation.

FIG. 5 is a flowchart illustrating still image processing.

FIG. 6 is a configuration diagram of a playback unit of a conventional digital VTR.

FIG. 7 is a flowchart showing an operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic tape 2 Magnetic head 5, 11 Error correction circuit 6, 8 Frame memory 7 Decompression circuit 12 Capstan motor 13 Microcomputer

Claims (8)

[Claims] 1. A reproducing apparatus which conveys a tape-shaped recording medium on which a large number of oblique tracks are formed and reproduces image data, wherein a recording mode of the reproduced image data is such that the tape-shaped recording medium is conveyed at a normal speed. Mode detecting means for detecting whether the first mode for recording the image data or the second mode for recording the image data by transporting the tape-shaped recording medium at a speed lower than the normal speed; Playback image detection means for detecting whether an image indicated by the playback image data is a moving image or a still image; andcontrolling a transport speed of the tape-shaped recording medium according to an output of the mode detection means and an output of the playback image detection means. A playback device comprising: 2. The tape control device according to claim 2, wherein the control unit controls the reproduction of the tape-shaped recording medium according to an output of the reproduction image detection unit when the recording mode of the reproduction image data changes from the second mode to the first mode. The reproducing apparatus according to claim 1, wherein the transport speed is determined. 3. When the recording mode of the reproduced image data changes from the second mode to the first mode, the control means determines that the reproduced image data indicates a still image. 3. The reproducing apparatus according to claim 2, wherein the transport speed of the tape-shaped recording medium is set to a speed according to the second mode. 4. When the recording mode of the reproduced image data changes from the second mode to the first mode, the control means determines that the reproduced image data indicates a moving image. 3. The reproducing apparatus according to claim 2, wherein the transport speed of the tape-shaped recording medium is set to a speed according to the first mode. 5. An apparatus according to claim 1, further comprising: an error correcting means for correcting an error in said reproduced image data; and a processing means for processing said reproduced image data in accordance with an output of said error correcting means.
A playback device according to claim 1. 6. The apparatus according to claim 5, wherein said error correction means corrects an error in said reproduced image data by using first and second parity data added when said image data is recorded. The playback device according to any one of the preceding claims. 7. The reproducing apparatus according to claim 1, wherein the image data is recorded with a reduced amount of information, and the second mode has a higher compression ratio than the first mode. . 8. The reproducing apparatus according to claim 1, wherein the number of tracks formed per unit time in the first mode is larger than that in the second mode.