JPH0832936A - Reproducing device and recording/reproducing device - Google Patents

Abstract

PURPOSE:To improve picture quality of specially reproduced images and to reduce the quantity of hardware. CONSTITUTION:The normal reproduction data to be reproduced in a normal reproduction mode and the special reproduction data to be reproduced in a special reproduction mode are recorded on a magnetic tape 1 at each prescribed position. In reference to a device which reproduces the tape 1, a single-segment memory 21 corresponding to a size equivalent to the special reproduction data obtained by at least two times head scanning operation with a reproduction head 2 is placed at a stage preceding a frame memory 7 which can store the special reproduction data equivalent to a single screen of specially reproduced images. The normal reproduction data are decoded by a normal reproduction data decoder 6. Meanwhile the special reproduction data are regenerated by a special reproduction signal regenerator 8 based on the data acquired by both memories 21 and 7 and therefore decoded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing apparatus and a recording / reproducing apparatus for reproducing a digital television signal recorded on a magnetic tape, and more particularly to a digital VTR.

[0002]

2. Description of the Related Art In a digital VTR, in the case of recording already compressed image data of a digital television signal, the input signal is recorded at the same rate and reproduced. The coding method and transmission method used in that case are MPEG (Moving Picture Expert Group).
The international standard method called is used. Since MPEG uses an inter-screen predictive coding technique for image data compression, the rotary head cannot read all the data on the tape during special playback, and the read playback data is continuous with the original data. Lost, mixed playback screen,
Problems such as missing and erroneous decoding occur. Therefore, the special reproduction data for forming the screen during special reproduction is generated by using the intra-coded image data of the input data, and the special reproduction data is recorded on the special reproduction data. As a result, it is possible to obtain a special reproduction image that is free from mixture, omission, and erroneous decoding during special reproduction.

First, an example of arrangement of special reproduction data recorded on a magnetic tape will be described. The special reproduction data is recorded on the magnetic tape in a layout as shown in FIG. 4A by a predetermined recording device. In the recording device, the special reproduction image output during special reproduction is divided into several super blocks for each screen. MPEG for super block
In this case, a set of pixels called a macro block includes a number corresponding to the amount that can be stored in the capacity of the recording packet.

The bit length of each orthogonal transform coefficient is fixed,
When the number of macroblocks in a recording packet is fixed, the trick play screen is divided into m superblocks as shown in FIG. 5A, and one superblock is shown as data in one recording packet. It arranges like 4 (b). Note that FIG. 4B is a more detailed data layout diagram of the trick play data area shown in FIG.

When the bit length of each orthogonal transform coefficient is variable and the number of macroblocks in the recording packet is also variable, the special reproduction screen is divided into k superblocks as shown in FIG. 5B. To do. If the maximum speed set for this special reproduction data area is N times speed (N is an even number), recording is repeatedly performed on (2 × N) tracks. Here, special reproduction data repeatedly recorded on (2 × N) tracks will be referred to as one segment. As a result, on the reproducing apparatus side, for example, in the case of two heads mounted 180 degrees opposite to each other on the rotary cylinder,
It is possible to read the special reproduction data of one segment in the special reproduction signal area complementarily at the following even speeds.

FIG. 6 shows the structure of a conventional reproducing apparatus. Figure 6
1, 1 is a magnetic tape, 2 is a reproducing head, 3 is a demodulator, 4 is an error correction decoder, 5 is a deformatter, 6 is a normal reproduction signal decoder, 7 is a frame memory, and 8 is a special reproduction signal reconstructor. , 9 are switches.

A conventional reproducing apparatus configured as above will be described. The reproducing head 2 reads the signal recorded on the magnetic tape 1 by the recording device, the demodulator 3 demodulates the reproduced signal, and outputs the demodulated signal to the error correction decoder 4. The error correction decoder 4 performs error correction on the demodulated signal and outputs it to the deformatter 5. The deformatter 5 restores the data in the recording packet unit to the original format and separates the normal reproduction data and the special reproduction data into the normal reproduction data decoder 6 and the special reproduction data into the frame memory. Output to 7. The normal reproduction signal decoder 6 decodes the signal processing performed on the recording device side as necessary, or outputs it to the switch 8 as it is. On the other hand, in the frame memory 7, when the data of the read recording packet is sequentially written and the special reproduction data for one screen is stored, the special reproduction signal reconstructor 8
Output to. At this time, since the tape running speed during special reproduction is different from that during normal reproduction, the head cannot read the data of the recording packet in the order of the special reproduction screen position. Therefore, when writing to the frame memory in the order of the read recording packets, information for specifying the writing position of the frame memory is recorded in advance in each recording packet on the recording device side. At this time, the position information of the first macroblock in the recording packet is recorded. Then, based on such information, writing to the frame memory is performed. The special reproduction signal reconstructor 8 restores the processing performed on the special reproduction data on the recording device side. For example, it is converted into a transmission packet format that can be decoded by the MPEG decoder and output to the switch 9. The switch 9 switches so that normal reproduction data is output during normal reproduction and special reproduction data is output during special reproduction.

[0008]

However, in the above-mentioned conventional configuration, when the data of the recording packet read at the time of special reproduction is sequentially written in the frame memory, if the number of macroblocks in the recording packet is variable, It had the drawback of not knowing where to write in memory. For example, the write position can be determined by the position information of the first macroblock in the recording packet. In this case, assuming that the minimum number of macroblocks in the recording packet is one, (the number of macroblocks x It is necessary to secure a memory amount of (recording packet capacity), which has a drawback that the memory amount becomes huge.

Further, when a recording packet is omitted due to an error, there is a disadvantage that the portion of the recording packet cannot be corrected because there is no information indicating which position on the special reproduction screen the data of the recording packet is. .

An object of the present invention is to solve the above drawbacks of the conventional reproducing apparatus.

[0011]

A first aspect of the present invention is a magnetic tape in which normal reproduction data, which is data to be reproduced during normal reproduction, and special reproduction data, which is data to be reproduced during special reproduction, are arranged and recorded at predetermined positions. In the device that reproduces
A buffer memory having a size corresponding to the special reproduction data obtained by at least two times of head scanning is arranged in the preceding stage of the frame memory for storing the special reproduction data for one screen of the special reproduction image.

A second aspect of the present invention is a recording packet number indicating the order of the recording packet divided into predetermined amounts of data in order from a predetermined position on the screen in the recording packet on the magnetic tape, and a special packet in the recording packet. Screen position information, which is information indicating the position on the screen of the reproduction data, is recorded, and the position where the special reproduction data in the recording packet is written to the frame memory is determined by the recording packet number and the screen position information during reproduction. It is characterized by doing.

[0013]

According to the present invention, when the data of the recording packet read at the time of special reproduction is sequentially written into the frame memory, the minimum required buffer memory is added to generate special reproduction data for one screen of special reproduction image. It is possible to reduce the amount of memory of the frame memory to be stored, and also to reduce the amount of information for determining the writing position to the frame memory for each recording packet on the recording device side. It does not reduce the recording capacity. Further, by adding the position information on the screen, the image in the error portion can be corrected.

According to the present invention, the recording packet number, which is the information indicating the order of the recording packets from the head of each special reproduction screen at the time of recording, and the special reproduction screen of the first macroblock among the macroblock data in the recording packet. When the special reproduction data is written to the frame memory at the time of reproduction, the memory amount of the frame memory constitutes one special reproduction image screen by recording the information indicating the position of No. It suffices to prepare the memory amount for the number of recording packets.

[0015]

1 is a block diagram of a reproducing apparatus according to a first embodiment of the present invention, in which 1 is a magnetic tape, 2 is a reproducing head, 3 is a demodulator, 4 is an error correction decoder, and 5 is a deformatter. , 6 is a normal reproduction data decoder, 7 is a frame memory, 8 is a special reproduction data reconstructor, 9 is a switch, 21
Indicates a buffer memory for one segment.

The operation of reproducing the magnetic tape recorded by dividing the digital television data into the normal reproduction data and the special reproduction data and recording them will be described below.

First, the signal recorded on the magnetic tape 1 is read by the reproducing head 2, the reproduced signal is demodulated by the demodulator 3 and output to the error correction decoder 4. The error correction decoder 4 performs error correction on the demodulated data and outputs it to the deformatter 5. The deformatter 5 restores the data in the recording packet unit to the original format and separates it into normal reproduction data and special reproduction data. The normal reproduction data is sent to the normal reproduction data decoder 6 and the special reproduction signal is used for one segment. Output to the buffer memory 21. The normal reproduction data decoder 6 decodes the signal processing performed on the recording device side as necessary, or outputs it to the switch 8 as it is. The 1-segment buffer memory 21 stores the special reproduction data for 1 segment which is complementarily read by two head scans from two magnetic heads provided on the rotary cylinder and facing each other by 180 °, and stores it in the frame memory 7. Output. In the frame memory 7, special reproduction data is sequentially written one segment at a time. When the data for one screen of the special reproduction image is stored, it is output to the special reproduction data reconstructor 8. The special reproduction data reconstructor 8 restores the processing performed on the special reproduction data on the recording device side. For example, it is converted into a transmission packet format that can be decoded by the MPEG decoder and output to the switch 9. The switch 9 switches so that normal reproduction data is output during normal reproduction and special reproduction data is output during special reproduction.

Whether the special reproduction data stored in the buffer memory is the head scan at the tth time (t is a positive integer), the head scan immediately before that (t-1) time or the head scan immediately after that (t + 1) time. A method of determining whether or not the head obtained by one of the pairs is used will be described with reference to FIG. In FIG. 3, a pair of (t−1) th and tth head scans read special reproduction data for the same one segment in a complementary manner, so that it is stored in the buffer memory. At this time, as a means for determining this, if the recording device side previously records the identification data indicating the same segment in the recording packets read by scanning at the (t-1) th time and the tth time, The identification data can be surely identified by reading the identification data during reproduction.

A case where screen position information indicating a position on the trick play screen is used as the identification data will be described with reference to FIG. The screen position information is recorded in the recording packet because it is necessary for recognizing the position of the data when decoding the special reproduction data.
As shown in FIG. 3B, it is assumed that the super block 1 of packet No. 1 and the super block 2 of packet No. 2 have been read in the (t-1) th head scan.
Next, it is assumed that the super block 3 of packet No. 3, the super block 4 of packet No. 4, and the super block 5 of packet No. 5 have been read in the t-th head scan. Then, in the (t + 1) th head scan, it is assumed that the super block 6 of packet No. 1 and the super block 7 of packet No. 2 have been read. Here, in the t-th head scan, packet Nos. 3, 4, and 5
The data of packet No. 1 and 2 could not be read, but the data of packet No. 1 and 2 read at the (t-1) th or (t + 1) th head scan. Are combined to form one segment of data. At this time, the smallest packet No. out of the packets read by the t-th head scan is 3, and the data recorded therein is the data of the super block 3. (T +
1) Each packet No. 2 in the first head scan
The superblock numbers of are compared to determine whether the superblock numbers have continuity. Since the packet No. 2 is the data of the super block 2 at the (t-1) th time, and the packet No. 2 is the data of the super block 7 at the (t + 1) th time, the head scanning at the (t-1) th time is performed. Since the data is the data of the same segment, the special reproduction data read by the two head scans is stored in the buffer memory and written in the frame memory.

With the above configuration, when the data of the recording packet read at the time of special reproduction is sequentially written in the frame memory, the minimum necessary buffer memory is added, so that the special reproduction data for one screen of special reproduction image is added. It is possible to reduce the amount of memory of the frame memory that stores the data, and to reduce the amount of information recorded for determining the writing position to the frame memory for each recording packet on the recording device side. It does not reduce the recording capacity of. Further, by adding the position information on the screen, the image in the error portion can be corrected.

The arrangement of special reproduction data has been described by taking the case of FIG. 4 as an example, but the arrangement is not limited to this, and any data arrangement may be used, and the head configuration of the rotary cylinder is 180.
Although they are opposed to each other, this may have an arbitrary configuration, and the special reproduction data arrangement suitable for the configuration may be used. Also, the number of recording packets in the trick play data area may be any number.

Further, as a special reproduction screen division method, FIG.
In the above, the data is divided into m super blocks, but this may be any number of divisions, and the data of one super block is contained in one recording packet, but an arbitrary number of recording packets may be used.

The special reproduction data stored in the buffer memory is supplied to the tth head scan (t is a positive integer) and the head scan (t-1) immediately before it or the head scan (t + 1) immediately thereafter. Although the example of the method for determining whether the pair of heads has been obtained has been described, this may be an arbitrary determination method. For example, if the recording device records information indicating each time the segment is updated, it is possible to determine which pair of heads the head has obtained by reading the information during special reproduction.

FIG. 2 shows the inside of a recording packet for recording the information indicating the order from the beginning of the screen in the recording packet and the position information on the screen in the recording / reproducing apparatus in the second embodiment of the present invention. , 31 is a recording packet header,
32 is special reproduction data, 41 is a recording packet number, 42
Indicates screen position information.

In each recording packet, a recording packet header 31 such as a synchronization signal, a recording packet number 41 which is information indicating the order from the top of the screen, and position information 4 on the screen.
2 and image data 32 are recorded. The recording packet number 41 is the same as the recording packet number 41 when the special reproduction data of one super block shown in FIG. 5 is recorded in one recording packet.
The super block number becomes equal to the recording packet number. The screen position information 42 is information indicating the position on the special reproduction screen of the head macroblock in the macroblock data in the recording packet. Since the macroblock data in the recording packet are arranged and recorded in the order on the screen, the information indicating the screen position only needs to know the position of the leading macroblock.

With the above configuration, when the special reproduction data is written to the frame memory, the memory amount of the frame memory should be prepared for the number of recording packets constituting one screen of the special reproduction image. Good.

Although the recording packet numbers are in order from the top of the screen, the order may be from any position on the screen.
Further, the screen position information is the position of the head macroblock in the recording packet on the special playback screen, but this may also be any macroblock. Further, in FIG. 2, the inside of the recording packet for recording the recording packet number and the position information on the screen is shown, but this may be any arrangement.

[0028]

As described above, according to the present invention,
When the data of the recording packets read during special playback is sequentially written to the frame memory, the minimum required buffer memory is added to increase the amount of memory in the frame memory that stores special playback data for one screen of special playback image. It is also possible to reduce the amount of recording information for determining the writing position to the frame memory for each recording packet on the recording device side, so that the recording capacity of special reproduction data is not reduced. . Further, by adding the position information on the screen, the image in the error portion can be corrected.

Further, in the present invention, the recording packet number, which is the information indicating the order of the recording packets from the head of each special reproduction screen at the time of recording, and the macroblock data in the recording packet, on the special reproduction screen of the first macroblock. When the special reproduction data is written to the frame memory by recording the information indicating the position of each of the recording packets and the special reproduction data is written to the frame memory, the memory capacity of the frame memory is the recording packets constituting one screen of the special reproduction image. All you have to do is prepare a few minutes of memory.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an internal structure of a recording packet in a recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 3 shows special reproduction data stored in a buffer memory,
It is determined whether the head scan of the t-th time (t is a positive integer) and the head scan (t−1) immediately before that or the head scan (t + 1) time immediately after that are obtained by the pair of heads. Diagram showing how to do

FIG. 4 is a diagram showing an arrangement example of special reproduction data.

FIG. 5 is a diagram showing an example of a trick play screen division method.

FIG. 6 is a block diagram showing the configuration of a conventional playback device.

[Explanation of symbols]

 1 magnetic tape 2 reproduction head 3 demodulator 4 error correction decoder 5 deformatter 6 normal reproduction data decoder 7 frame memory 8 special reproduction data reconstructor 9 switch 21 1 segment buffer memory 31 recording packet header 32 special reproduction data 41 Recording packet number 42 Screen position information

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Morimoto 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A device for reproducing a magnetic tape in which normal reproduction data, which is data to be reproduced at the time of normal reproduction, and special reproduction data, which is data to be reproduced at the time of special reproduction, are arranged at predetermined positions and recorded, at least 2. A reproducing apparatus characterized in that a buffer memory having a size corresponding to the special reproduction data obtained by performing head scanning once is arranged in front of a frame memory capable of accumulating special reproduction data for one screen of a special reproduction image. 2. A reproducing apparatus according to claim 1, wherein the special reproduction data is recorded on the magnetic tape repeatedly a plurality of times in the tape running direction. 3. A t-th head scan (t is a positive integer) and a head scan (t-1) -th set immediately before it, or a t-th head scan and a head scan (t + 1) -th set immediately after that. 2. Which of the two sets of special reproduction data is to be stored in the buffer memory is identified by the identification data previously recorded in the recording packet on the magnetic tape. Playback device. 4. The reproducing apparatus according to claim 3, wherein the identification data is information indicating that the content of the special reproduction data repeatedly recorded a plurality of times has been updated. 5. The reproducing apparatus according to claim 3, wherein the identification data is screen position information indicating a position on the special reproduction screen. 6. A recording packet on a magnetic tape is divided into predetermined data amounts in order from a predetermined position on a screen, and when each divided data is recorded in the recording packet, the recording packet is divided into each recording packet. The recording packet number indicating the order and the screen position information that is the information indicating the position on the screen of the special reproduction data in the recording packet are recorded in the recording packet, and at the time of reproduction, the recording packet number and the screen position information are used. A recording / reproducing apparatus, characterized in that the write position of the special reproduction data in the recording packet to the frame memory is determined.