JP3125479B2 - Playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital V
The present invention relates to a digital video signal reproducing apparatus in which one frame such as a TR is divided into a plurality of tracks and recorded.

[0002]

2. Description of the Related Art For example, in a consumer digital VTR, a segment recording method is adopted, and one frame is divided into, for example, 10 tracks and recorded. As such a consumer digital VTR playback apparatus, for example, an apparatus as shown in FIG. 5 has been considered.

That is, in the figure, reproduced RF data reproduced by a head 1 is amplified to an appropriate level by a reproducing amplifier 2 and then converted into a digital signal by a decoding circuit 3. The converted digital signal is supplied to an ID detection circuit 4 where an ID such as a frame identification signal and a track number in the signal is detected, and the detected ID is stored in a first frame memory 5 based on a write address. Written.

The frame memory 5 stores one frame (1
One of the roles is to keep the read phase constant regardless of the phase of the digital signal to be written. This operation is performed by reading a digital signal written based on the ID based on an address based on a fixed cycle synchronized with the subsequent stage.

The digital signal read from the frame memory 5 is written to a second frame memory 9 through an error correction circuit 6, a deframing circuit 7, and an inverse DCT conversion circuit 8. At this time, the writing to the frame memory 9 is performed on the basis of the address of a certain cycle because the frame synchronization is established after the reading from the frame memory 5. Reading is also performed on the basis of the same fixed cycle address. The same applies to the two sets of field memories 10 and 11 at the subsequent stage.

The frame memory 9 has a capacity for one frame, and its main role is to return a digital signal processed in a frame to a field. That is, the digital signal processed by the inverse DCT conversion circuit 8 can be decomposed into odd and even fields.
Therefore, at the time of reading, the field is divided into two systems of odd and even fields, and write destinations are respectively set to the field memories 10 and 11.
To return to the field.

The role of the field memories 10 and 11 is to restore shuffling. That is, it is performed at the time of writing, and is read back in order to return to the original video sequence. Then, a sync signal is added to the signals read from the field memories 10 and 11 by a sync adding circuit 12, converted into an analog signal by a D / A conversion circuit 13, and output from an output terminal 14. Thus, the reproduction of the digital video signal is performed.

By the way, in such a reproducing apparatus, it has been studied to perform so-called slow reproduction by setting the reproduction speed lower than that at the time of recording. In this case, in the above-described segment recording, a reproduced image cannot be output unless all 10 tracks are reproduced. Therefore, it is conceivable to perform slow reproduction by successively accumulating the fetched reproduction signals in a memory and reading them in bursts when one frame is completed.

In this case, for example, the following method can be used to determine when one frame is completed.
1) When the last data of the currently accumulated frame is extracted. 2) When the data of the frame next to the currently stored frame is extracted.

However, in these methods, for example, in the method 1), when the last data is lost due to dropout or the like, it may not be possible to determine the time point. In the method 2), the next frame may be extracted before the last data of the accumulated frame is extracted in a good state. Therefore, in these cases, there is a possibility that a good reproduced image cannot be obtained. The present application has been made in view of such a point.

[0011]

The problem to be solved is that in the prior art, it is sometimes impossible to obtain a good reproduced image depending on the state of the reproduced signal.

[0012]

According to a first aspect of the present invention, in a digital video signal reproducing apparatus in which one frame is divided into a plurality of tracks and recorded, reproduction is performed at a lower reproduction speed than at the time of recording. In this case, the reproduction signal is stored in the memories 21 and 22 so that the next processing is executed when the storage of one frame is completed, and the frame identification signal and the track number in the reproduction signal are detected. The reproduction apparatus is characterized in that when the second and subsequent tracks of the next frame are reproduced in the reproduction order, it is determined that the accumulation in the memory has been completed.

According to a second means of the present invention, the memory is provided with two sets (21, 22), each of which stores one frame and the next frame identified by the frame identification signal, The reproducing apparatus according to the first means, wherein when the second and subsequent tracks of the next frame are accumulated, it is determined that the accumulation of the other frame is completed.

A third means according to the present invention is that the two sets of memories 21 and 22 each have a capacity of one field, and that the odd and even fields in the reproduced signal are determined and each of the predetermined fields is determined. Characterized in that only the reproduction signal of the field is stored.
A reproducing apparatus according to the above means.

According to a fourth aspect of the present invention, there is provided a reproducing apparatus according to the third aspect, wherein the two sets of memories 21 and 22 are used by dividing one set of one frame memory 9. It is.

[0016]

According to this, when the second and subsequent tracks of the next frame are reproduced in the reproduction order, it is determined that the accumulation of the previous frame in the memory has been completed. And a good reproduced image can always be obtained.

[0017]

1, two sets of memories 21 and 22 are provided in place of the above-mentioned memory 9 in FIG. Furthermore, these memories 2
For memories 1 and 22, memories 31 and 32 corresponding to the memories 10 and 11 described above are directly arranged.

In this device, the format of a signal taken out by the head 1 and read out from the first frame memory 5 is as shown in FIG. 2, for example. That is, the drawing corresponds to the recording format of one track. In this figure, 147 sync blocks are provided in one track, and a reproduced image of one frame is obtained with 10 tracks = 1470 sync blocks. Each of these sync blocks is composed of a sync ID and data, in which a frame identification signal and a track number are written.

Therefore, in the above-mentioned two sets of memories 21 and 22, data excluding those which cannot be corrected by the error correction circuit 6 are sorted by the above-mentioned frame identification signal and written. At the same time, the track number is detected. For example, when the second and subsequent tracks of the next frame are stored in one memory 21 (22), the other memory 22 (21)
It is determined that the accumulation of data in the data has been completed.

In accordance with this determination, the data in the memory 21 or 22 whose storage has been completed is transferred to the memory 31 or 32 in a burst manner. At this time, shuffling return processing is performed. Thereafter, the data in the memory 31 or 32 is repeatedly read out,
2, a synchronizing signal is added, converted into an analog signal by the D / A conversion circuit 13, and output from the output terminal 14, thereby performing slow reproduction.

That is, in this device, for example, when writing is performed from the memory 21 during slow reproduction in the forward direction, when the second track and subsequent tracks of the memory 22 are written as shown in FIG. 21 to memory 31
Are transferred in bursts. Further, when writing is performed from the memory 22, when the second track and subsequent tracks of the memory 21 are written as shown in B of the same figure, transfer from the memory 22 to the memory 32 is performed in a burst manner.

Alternatively, at the time of slow reproduction in the reverse direction,
When the data is written from the second track, the data is transferred from the memory 22 to the memory 32 in a burst manner when the second and subsequent tracks from the bottom of the memory 21 are written as shown in FIG. Further, when writing is performed from the memory 21, when the second and subsequent tracks from the bottom of the memory 22 are written as shown in B of the same figure, transfer from the memory 21 to the memory 31 is performed in a burst manner.

Therefore, in this device, even if the last data is lost due to dropout or the like, the second frame of the next frame is lost.
Since the discrimination is performed when the data after the track is accumulated, there is no possibility that the discrimination cannot be performed. When the second and subsequent tracks of the next frame are accumulated, the extraction of the last data of the previous accumulated frame has been completed, and there is no possibility that the next frame will be extracted before the data is extracted in a good state. .

According to the above-described apparatus, when the second and subsequent tracks of the next frame are reproduced in the reproduction order, it is determined that the accumulation of the previous frame in the memory has been completed. Regardless of the state, a good reproduced image can always be obtained.

In the above-described apparatus, two sets of memories 2
Each of 1 and 22 may have a capacity of one field, and odd and even fields in a reproduction signal may be determined, and only the reproduction signal of a predetermined field may be stored. In this case, two sets of memories may be used by dividing one set of one frame memory.

[0026]

According to the present invention, when the second and subsequent tracks of the next frame are reproduced in the reproduction order, it is determined that the accumulation of the previous frame in the memory has been completed. Regardless of the state, a good reproduced image can always be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an example of a playback device according to the present invention.

FIG. 2 is a diagram for explaining an example of the recording format.

FIG. 3 is a diagram for explaining an example of the operation of the memory.

FIG. 4 is a diagram for explaining another example of the operation of the memory.

FIG. 5 is a configuration diagram of a conventional reproducing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Head 2 Reproduction amplifier 3 Decoding circuit 4 ID detection circuit 5 Frame memory 6 Error correction circuit 7 Deframing circuit 8 Inverse DCT conversion circuit 12 Sink addition circuit 13 D / A conversion circuit 14 Output terminal 21, 22 Memory 31, 32 memory

Claims (4)

(57) [Claims] In a digital video signal reproducing apparatus in which one frame is divided into a plurality of tracks and recorded, when reproducing at a lower reproduction speed than at the time of recording, the reproduced signal is stored in a memory. When the accumulation of the frame is completed, the next processing is executed, the frame identification signal and the track number in the reproduction signal are detected, and the second and subsequent tracks of the next frame are reproduced in the reproduction order. A playback device configured to determine that the storage of the memory has been completed. 2. The memory is provided with two sets, each storing one frame and the next frame identified by the frame identification signal, and storing the second and subsequent tracks of the next frame. 2. The reproducing apparatus according to claim 1, wherein when the recording is performed, it is determined that the other storage is completed. 3. The two sets of memories each have a capacity of one field. Odd and even fields in the reproduced signal are determined, and only the reproduced signal of a predetermined field is stored. 3. The reproducing apparatus according to claim 2, wherein 4. The reproducing apparatus according to claim 3, wherein said two sets of memories are used by dividing one set of one frame memory.