JPH08275106A - Image data recording and reproducing device - Google Patents

Abstract

PURPOSE: To select a usual reproduction state or a special reproduction state without disturbance in an image by providing a flag to digital image data subjected to high efficiency coding processing for each prescribed data unit including a synchronizing signal. CONSTITUTION: A data rate conversion circuit 13 converts a data rate of an MPEG bit stream outputted from a receiver 11 into a data rate recorded in a VTR 23. Furthermore, a simple decoder 16 extracts only one image from the MPEG stream and a variable length coding circuit 17 applies decoding processing to the image. A special reproduction data generating circuit 18 obtains header information from the simple decoder 16 to extract a DC component and a low frequency component from the decoded data and gives special reproduction data in response to number of multiple speed to buffers 19, 20, 21. A recording selector 14 converts outputs of the conversion circuit 13 and the buffers 15, 19, 20, 21 in the order of tape recording format and outputs the result to which various flags are added. Since a reproduction side detects an EOF flag representing the end of image data to execute changeover, no disturbance is caused in the image at changeover.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data recording / reproducing apparatus for recording and reproducing digital image data compressed by a high-efficiency encoding process on a recording medium, and particularly improving its special reproduction function. Regarding things.

[0002]

2. Description of the Related Art As is well known, in recent years, a technique of digitizing an image signal and recording it on a recording medium such as a tape has been put into practical use. In this case, since the digital image data obtained by digitizing the image signal has an enormous amount of data as it is, a large capacity recording medium is required. For this reason, MPEG (Moving Picture Image C
As seen in oding Experts Group), high-efficiency encoding processing is applied to digital image data to compress it, and the amount of data is reduced.

By the way, special reproduction such as high-speed reproduction is carried out in a state in which the digital image data which has been subjected to such high efficiency encoding processing is recorded on a tape by a VTR (video tape recorder) or the like by a helical scan system. In this case, since the reproducing head travels across a plurality of helical tracks formed on the tape, digital image data will be read intermittently.

This means that the digital image data obtained at the time of special reproduction loses continuity without any correction, and the digital image data subjected to the high-efficiency coding processing utilizing the correlation between frames. When is recorded, it becomes difficult to display an image. Therefore, in order to solve such a problem, a recording / reproducing means as disclosed in, for example, Japanese Patent Laid-Open No. 6-65298 is currently used.

In this recording / reproducing means, several special speeds for performing special reproduction are set by using the period of the pilot signal to create special reproduction data corresponding to each special speed, and each special reproduction is performed. The data for recording is recorded at a position on the tape through which the reproducing head passes during the corresponding double-speed reproduction, thereby reducing the image quality deterioration that appears remarkably during low-speed reproduction and obtaining a stable and easy-to-see special reproduction image. .

However, in the conventional recording / reproducing means as described above, when the normal reproduction state is switched to the special reproduction state or when the special reproduction state is changed to the normal reproduction state, the reproduced digital image data is reproduced. Unless the decoding process is performed, the continuity of the digital image data is ignored and switching is performed, which causes a problem that the image is temporarily disturbed.

[0007]

As described above, in the conventional recording / reproducing means for recording / reproducing the digital image data which has been subjected to the high-efficiency encoding process, the image is not displayed when the normal reproduction state and the special reproduction state are switched. It has the problem of being temporarily disturbed.

Therefore, the present invention has been made in consideration of the above circumstances, and a recording medium in which digital image data that has been subjected to high-efficiency encoding processing is recorded is set in a normal reproduction state without disturbing the image. It is an object of the present invention to provide an extremely good image data recording / reproducing apparatus capable of switching to a special reproduction state.

[0009]

According to an image data recording / reproducing apparatus of the present invention, digital image data which has been subjected to high-efficiency encoding processing is processed to generate an image for each predetermined data unit including a synchronization signal. A recording means for adding a flag indicating the presence or absence of a break, and a reproducing means for detecting the flag and reproducing the digital image data up to the boundary of the image and then performing a switching operation when switching between the normal reproduction state and the special reproduction state. I have it.

[0010]

According to the above-described structure, a flag indicating the presence / absence of an image break is added to each predetermined data unit including a sync signal at the time of recording, and the flag is set at the time of switching between the normal reproduction state and the special reproduction state. Since the switching operation is performed after the digital image data is detected and reproduced up to the boundary of the image, the image is disturbed with respect to the recording medium on which the digital image data subjected to the high efficiency encoding processing is recorded. Instead, the normal reproduction state and the special reproduction state can be switched.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to describing one embodiment of the present invention, the principle of the present invention will be briefly described below. First, in this description, it is assumed that high-efficiency encoding processing by MPEG is used. That is, as shown in FIG. 3, in MPEG, 1 GOP (Group of Pictu) is used.
re) is composed of 12 frames.

The twelve frames are one I picture which is an intra-frame encoded image and three P which are inter-coded images which are already encoded and predicted from a temporally previous frame. A picture and eight Bs that are inter-frame coded images predicted from two frames temporally preceding and following
Pictures are arranged in the arrangement shown in FIG.

Further, as shown in FIG. 4, the rotary drum head H of the VTR is installed on the circumferential side of the rotary drum D, and a pair of head portions h1, which are set to have opposite azimuth angles + and-, respectively. A single-sided double azimuth head with h2 is used. Then, the winding angle of the tape (not shown) with respect to the rotary drum D is set to 180 °, and the rotary drum head H is rotated 9000 rpm to secure a recording area corresponding to 10 helical tracks per 1/30 second on the tape. As described above, the running speed of the tape is defined.

FIG. 5 shows a recording format on the tape T. That is, a plurality of helical tracks are alternately formed on the tape T so as to have the reverse azimuth angles + and −. On each helical track, pilot signals F0, F1, F2 having three types of frequencies are recorded at the cycle of pilot signals F0, F1, F0, F2, superposed on the originally recorded image data and audio data. It In FIG. 5, arrow a indicates the running direction of the tape T, and arrow b indicates the scanning direction of the heads h1 and h2.

FIG. 6 shows a rotary drum head H having a width of 20 μm in which a single track has a track width of 10 μm.
Shows the voltage level generated at the center of the rotary drum head H by the pilot signals F1 and F2 when scanning is performed. In FIG. 6, it can be seen that when the center of the rotary drum head H reaches the center of the helical track on which the pilot signal F0 is recorded, the voltage level of F1-F2 is 0V. That is, it is possible to perform tracking servo by controlling the tape running servo motor so that the voltage level of F1-F2 becomes 0V.

Then, by checking the slope of the voltage level of F1-F2 in the tracking servo-executed state, it is determined which pilot signal F0 is in the period of the pilot signals F0, F1, F0, F2. It becomes possible to do. For example, if the slope of the voltage level of F1-F2 is rising to the right, the pilot signal F
It can be seen that the pilot signal F0 is between 2, F0 and F1.

FIG. 7 shows a recording format on the tape T to which a recording area for special reproduction data used in the present invention is added, and +4 (-2), +8 (-6), +24 (-22).
The relationship with the locus of the rotary drum head H when double speed reproduction is performed is shown. In FIG. 7, F0, F1, and F2 indicate pilot signals, and + and − indicate azimuth angles. The circled + and-respectively indicate the azimuth angle of the rotary drum head H during special reproduction.

FIG. 8 shows +4 (-2), +8 (-6), +
The respective envelopes of the reproduction signals obtained from the rotary drum head H when 24 (-22) times speed reproduction is performed are shown. Each envelope shown in FIG. 8 has 10
The same helical track with a track width of 10 μm
This is due to the result of scanning with the width head. In FIG. 8, the region T1 is for +4 (-2) times speed, and the region T2 is +8.
The (-6) double speed data area T3 is a +24 (-22) double speed data recording area.

As shown in FIG. 7, the special reproduction data area on the tape T has a 4-track cycle, and the special reproduction speed is a multiple of 4 in the forward direction, and in the reverse direction from the normal speed to the double speed. Since the obtained double speed number is taken, there is always a point where the tracking servo is performed at one position in the four helical tracks corresponding to the period of the pilot signal. The tracking servo method at this time will be specifically described.

That is, +4 (-2) and +24 (-2
2) During double-speed special reproduction, a pilot signal is detected at the central portion of the helical track, and the detected pilot signal is output at 0 V with a downward slope of the voltage level of F1-F2 shown in FIG. By controlling so that, the tracking servo can be performed, and the respective special reproduction data can be reproduced.

Similarly, at the time of the special reproduction of +8 (-6) times the speed, F at the central portion of the helical track.
By controlling the voltage level of 1-F2 to increase to the right with a slope of 0 V, tracking servo can be performed, and special reproduction data can be reproduced.

FIG. 9 shows a detailed recording format on the tape T. First, the image data recording area is divided into 135 Sync. And 1Sync
Is configured as shown in FIG. Figure 10
In (a), SYNC is a synchronization pattern, and ID
Is identification information representing the number of the recorded helical track. The image data area has an image data recording capacity of 77 bytes per 1 sync.

FIG. 10 (b) shows the structure of Transport Packet which is a synchronization unit in MPEG transmission. 1Tr
Ansport Packet consists of 188 bytes and is 5Sync
(Image data area 77 x 5 = 385 bytes) 2 Transp
An ort Packet (188 × 2 = 376 bytes) is recorded. At this time, 9 bytes are available, but several bits are used as flag information shown below.

That is, in 5Sync, that is, 2Transp
It is used as a 2-bit flag (EOF) indicating which of the image data included in the ort Packet has an End Of Flag for indicating the end of the picture data. In addition, a 1-bit flag (TP) indicating whether the area is for special reproduction, and when it is an area for data for special reproduction, a 1-bit flag (TU) indicating whether this area is used for special reproduction. ), The special reproduction data is used as a 3-bit flag (TN) indicating how many times the data is for.

When the normal reproduction state is changed to the special reproduction state, the EOF flag is checked to confirm that the En
Sync including Transport Packet in which d Of Flag exists
Send the block to the decoder. After that, by looking at the TU flag, TP flag, and TN flag, it is determined what speed the trick play data is, and the trick play data is transmitted.

In FIG. 9, 12Sync and 1
3Sync is a data recording area for +4 (-2) times speed, 20Sync is a data recording area for +8 (-6) times speed, and 5Sync is a data recording area for +24 (-22) times speed. That is, in 4 helical tracks, 50Sync, +8 at +4 (-2) times speed.
There is a recording capacity of 40 Sync at (-6) times speed and 30 Sync at +24 (-22) times speed. For this reason, a total of 120 sync exists for each of the four tracks as a recording area for special reproduction data.

Based on the above principle,
An embodiment of the present invention will be described in detail with reference to the drawings. First, FIG. 1 shows the configuration on the recording side. That is, the two receivers 11 and 12 take out only the MPEG bit stream from the transmission data received via an antenna or a cable (not shown). Of these, the bit stream output from the receiver 11 is supplied to the data rate conversion circuit 13.

The data rate conversion circuit 13 converts the data rate of the MPEG bit stream output from the receiver 11 into a data rate recordable in the VTR 23, which will be described later, and also +4 (-, which will be described later).
2) × buffer 19, +8 (−6) × buffer 20 and +24 (−22) × data is output to the recording system selector 14 in synchronization with the data output from the buffer 21.

The bit stream output from the receiver 12 is supplied to the external data input buffer 15. The external data input buffer 15 converts the data rate of the MPEG bit stream output from the receiver 12 into the data rate of the special reproduction data of the VTR 23 and outputs it to the recording system selector 14.

On the other hand, M output from the receiver 11
The PEG bit stream is supplied to the simple decoder 16 and only the I-picture image data is extracted. The image data of the I picture extracted by the simple decoder 16 is supplied to the variable length code decoding circuit 17 to be subjected to the variable length code decoding processing, and then is supplied to the special reproduction data creation circuit 18. .

The special reproduction data creating circuit 18 obtains various header information necessary for MPEG reproduction from the simple decoder 16 to obtain DC (DC) of the image data output from the variable length code decoding circuit 17. ) Component and AC
From the low frequency of the (AC) coefficient, three coefficients are extracted and output to the above +4 (−2) × buffer 19.

Further, the special reproduction data creating circuit 18 is
By obtaining various header information required for MPEG reproduction from the simple decoder 16, the DC component of the image data output from the variable length code decoding circuit 17 and the two low-frequency components of the AC coefficient are extracted. , Above +8 (-6)
Output to the buffer 20.

Further, the special reproduction data creation circuit 18
Obtains various header information necessary for MPEG reproduction from the simple decoder 16 to extract only the DC component of the image data output from the variable length code decoding circuit 17, and obtains +24 (−22) × It is outputting to the buffer 21.

These +4 (-2) × buffer 19, +8
The (−6) × buffer 20 and the +24 (−22) × buffer 21 store the data respectively output from the trick-play data creating circuit 18, and the recording system selector 14 orders the tape recording formats. It is converted to and output.

In this recording system selector 14, the output data of the data rate conversion circuit 13, the output data of the external data input buffer 15, and the output data of each of the buffers 19 to 21 are arranged so that 2 Transport Packets are included in 5 Sync. , EOF flag, TP flag, TU flag and TN
It is output with a flag added.

When the special reproduction is used, the recording system selector 14 does not select the output data of the external data input buffer 15, but selects the necessary data from the output data of the buffers 19 to 21, and the I / F. The data is output to the (interface) circuit 22 according to the recording format on the tape. When the special reproduction is not used, the recording system selector 14 selects necessary data from the buffers 19 to 21 and outputs it to the I / F circuit 22 according to the recording format on the tape.

The I / F circuit 22 is a recording system selector 1
The error correction code parity, the synchronizing signal, the ID signal, etc. are added to the data output from
It is output to 23. The VTR 23 is for recording by forming 10 helical tracks per 1/30 second by the rotary drum head H equipped with the one-sided double azimuth head as described above.

Next, FIG. 2 shows the structure on the reproducing side.
That is, the reproduction data obtained from the VTR 23 is
After being supplied to the I / F circuit 24 and subjected to error correction processing, it is supplied to the reproduction system selector 25. The reproduction system selector 25 switches the data output destination based on the external operation signal indicating whether or not the special reproduction is performed. That is, the reproduction system selector 25 is switched to output the input data to the data rate conversion circuit 26 in the case of normal reproduction.

In the case of special reproduction, the reproduction system selector 25 sends to the data rate conversion circuit 26 the special block after sending up to the Sync block including the Transport Packet in which the End Of Flag exists by looking at the EOF flag. The TP flag, TU flag and TN flag of the data for use are confirmed and output to the reproduction system buffer 27. Further, when reproducing the data using the special reproduction area for other than the special reproduction, the reproduction system selector 25 confirms the TP flag and the TU flag after receiving the reproduction data, and outputs the data to the external data output buffer 28. It is outputting.

Of these, the data rate conversion 26 is
The normal reproduction data obtained from the VTR 23 is transferred to the decoder 2
9 is converted into the data rate required by the decoder 9 and the decoder 29
Is output to. In addition, the external data output buffer 2
8 outputs the output data from the reproduction system selector 25 to the decoder 30.

Further, the reproduction system buffer 27 stores the special reproduction data output from the reproduction system selector 25 for one frame, and then, during the special reproduction in the forward direction, reads the data in the stored order and supplies it to the decoder 29. However, during special playback in the reverse direction, the data is read out and output to the decoder 29 in the reverse order of the stored order. These decoders 29, 30
Outputs an analog image signal and an audio signal by performing a decoding process on an MPEG bit stream and performing D / A (digital / analog) conversion.

Therefore, according to the configuration of the above embodiment, when the normal reproduction state is switched to the special reproduction state or when the special reproduction state is changed to the normal reproduction state, the End Of Flag indicating the end of the picture data is displayed. Since the presence or absence of the image is detected by the EOF flag and the switching is executed after the image data is output until the image is divided, it is possible to perform the smooth switching without the disturbance of the image at the time of the switching. Further, since data other than the special reproduction data can be recorded in the special reproduction data recording area, the degree of freedom in handling can be increased. The present invention is not limited to the above-described embodiment, and can be variously modified and implemented without departing from the scope of the invention.

[0043]

As described above in detail, according to the present invention,
A very good image data recording / reproducing apparatus capable of switching between a normal reproduction state and a special reproduction state without disturbing an image on a recording medium on which digital image data subjected to high efficiency encoding processing is recorded. Can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a recording side, showing an embodiment of an image data recording / reproducing apparatus according to the present invention.

FIG. 2 is a block diagram showing the reproducing side of the embodiment.

FIG. 3 is a diagram shown for explaining a frame forming one GOP in MPEG.

FIG. 4 is a view for explaining the structure of a rotary drum head H of a VTR.

FIG. 5 is a diagram shown for explaining a recording format on a tape.

FIG. 6 is a diagram shown for explaining a voltage level obtained from a rotary drum head by a pilot signal.

FIG. 7 is a diagram for explaining a relationship between a recording format of special reproduction data on a tape and a locus of a rotary drum head during double speed reproduction.

FIG. 8 is a diagram for explaining an envelope of a reproduction signal obtained from the rotary drum head during double speed reproduction.

FIG. 9 is a diagram shown for explaining a detailed recording format of an image data recording area on a tape.

FIG. 10 is a diagram shown for explaining the configuration of 1Sync and 1Transport Packet.

[Explanation of symbols]

11, 12 ... Receiver, 13 ... Data rate conversion circuit,
14 ... Recording system selector, 15 ... External data input buffer, 16 ... Simple decoder, 17 ... Variable length code decoding circuit, 18 ... Special reproduction data creating circuit, 19 ... +4 (-2)
X buffer, 20 ... + 8 (-6) x buffer, 21 ... +
24 (−22) × buffer, 22 ... I / F circuit, 23 ...
VTR, 24 ... I / F circuit, 25 ... Reproduction system selector, 2
6 ... Data rate conversion circuit, 27 ... Playback system buffer, 2
8 ... External data output buffer, 29, 30 ... Decoder.

Claims (3)

[Claims] 1. A recording means for adding a flag indicating presence / absence of an image delimiter to each digital image data which has been subjected to high-efficiency encoding processing for each predetermined data unit including a sync signal, and normal reproduction. Image data recording / reproducing, which is provided with a reproducing unit which detects the flag and reproduces the digital image data up to an image boundary before switching between the state and the special reproduction state. apparatus. 2. The recording means is required to display an image during special reproduction, in correspondence with a plurality of preset special reproduction speeds from digital image data which has been subjected to high efficiency encoding processing. Generating means for generating special reproduction data, and special reproduction data generated by the generating means in correspondence with each of a plurality of special reproduction speeds are arranged in time series together with the digital image data to form a recording medium. And a recording control unit that adds a flag indicating the presence or absence of an image break for each predetermined data unit including a synchronization signal that is a recording unit on the recording medium, and the reproducing unit is operated by an external operation. In a state where switching from the special reproduction state to the normal reproduction state is requested, the special reproduction data reproduced from the recording medium according to the special reproduction speed at the special reproduction is Playback is performed from the recording medium during normal playback in a state where switching from the normal playback state to the special playback state is requested by an external operation after the image has been played back up to the break of the image based on the lag. 2. The image data recording / reproducing apparatus according to claim 1, further comprising a switching control unit which performs a switching operation after reproducing up to an image division based on the flag. 3. The recording means records external data, instead of the special reproduction data, in a recording area of the special reproduction data of the recording medium, and a synchronization signal as a recording unit to the recording medium. External data recording control means for adding a second flag indicating that the external data has been recorded for each predetermined data unit including the reproduction means, wherein the reproduction means reproduces the data reproduced from the recording medium in the special reproduction state. 3. The image data recording according to claim 2, further comprising a discriminating means for judging the data reproduced from the recording medium in the special reproduction state as the external data based on the presence of the second flag in the. Playback device.