JPH04176284A - Memory controller - Google Patents

Abstract

PURPOSE:To accurately detect an edition point by reading out a signal written in a memory after the prescribed period and continuing the readout at the time of writing interruption to the written latest signal. CONSTITUTION:During the readout of a field memory 5, a stop signal is inputted to a field detection device 9 from a system control circuit 11, a counter 10 is not stopped, and a memory reading control circuit 8 continues memory reading. When the field detection device 9 detects a field memory 7 of the latest reproduction signal, the operation of the counter 10 is interrupted, and the shift to a field memory 4 is stopped. At this point, the memory reading control circuit 8 continues the reading of the field memory 7. Therefore, since the picture of the field read out from the memory is the latest signal to be written in the memory reproduced finally, the edition point can be strictly decided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a memory control device in a digital recording/reproducing device.

[Conventional technology]

As described in Japanese Unexamined Patent Application Publication No. 1-272276, conventional devices store playback signals without going through memory so that the tape position and playback screen correspond to each other during mode transition during editing, and editing points can be accurately searched. A method has been proposed that performs noiseless playback by switching timely between a state in which the signal is always output and a state in which the signal is transmitted via memory.

[Problem to be solved by the invention]

In the above conventional technology, when the playback head does not go on-track during variable speed playback and the signal is played back at a position where its locus spans multiple recording tracks, the playback image signal stored in the image memory is The reproduced image signals of the recording tracks of the book are mixed. Similarly, the playback signal that does not go through memory can be output as a mixture of playback image signals from multiple recording tracks, and no matter which output is selected, a signal containing a mixture of multiple recording tracks will be output. Output. Even when changing the playback mode, the signal output is a mixture of signals from multiple recording tracks, so it is impossible to detect the playback output image and editing points in the same image unit.
There was a problem that the same reproduced image could not be output.

An object of the present invention is to solve the above-mentioned problems, output the same image without mixing fields or frames of the reproduction signal on the image during variable speed reproduction of various speeds, and
It is an object of the present invention to provide a memory control device that can accurately detect editing points and obtain the latest reproduced signal output.

[Means to solve the problem]

In order to achieve the above purpose, fields of the reproduced image signal are detected using memory for multiple fields, signals of the same field are stored in the same memory, and reproduced until all signals of that field are reproduced. Continue operation. Then, the operation of the field memory is controlled so that reading is started from the memory in which all the signals of the field are stored, and the field being read is detected to determine the operating state.

[Effect]

A field detector that performs field detection detects the field and its end of the reproduced image signal, and determines whether to stop writing to the memory or not and starts writing to the next memory depending on the state of the operation mode. Determine whether or not. When reading from the memory, the field detector on the reading side continues to read signals from the memory that has not been written to, and controls the memory so that it always reads the last field memory that has been written, regardless of the operation mode. do.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1st
The figure shows an apparatus for reproducing a digital video signal recorded on the tape shown in FIG.

Here, 1 is a field detector that detects a field of reproduced data, 2 is a counter that controls the memory write control circuit 3, 4 to 7 are field memories, 8 is a memory read control circuit, and 9 is a memory read control circuit. A field detector detects the output field and controls a counter 10, 10 is a counter that controls a memory read control circuit, and 11 is a system control circuit. Furthermore, FIG. 2 shows the track spacing on a tape in which a digital television signal is divided into three segments for each field and further divided into two channels. 14a to 16b are field n, 17a to 19b are field n +1.20
A-20b is a track in which segment O of field n+2 is recorded, and 21a to 22b are tracks played back during 1/4 speed playback.

The digital video signals of the tracks 21a to 22b being reproduced at 174 times the speed are input to the field detector 1 and the memory write control circuit 3. Field detection circuit 1 detects that n fields have been reproduced from the input digital video signal, and outputs a continuation signal to counter 2 in accordance with an operation continuation signal from system control circuit 11. The counter 2 continues counting according to the continuation signal input from the field detection circuit 1 and sends its output to the memory write control circuit 3. The memory write control circuit 3 sends a control signal for writing the digital video signal to the field memory 4 from the reproduced digital video signal and the signal input from the counter 2 together with the digital video signal to the field memory 4 . field memory 4
Then, the input digital video signal of field n is stored in accordance with the input control signal. Similarly, the digital video signal of field n+1 reproduced from tracks 21a to 21b is stored in field memory 5, and the reproduced digital video signal of field n+2 is stored in field 6.

At the time when the playback digital signal starts to be stored in the field 6, the field memory 4 has already stored all the digital video signals of the field n. Read and output. Further, information on the field n being read from the memory read control circuit 8 is sent to the field detection circuit 9. The field detection circuit 9 receives information from the field readout control circuit 8 and the system control circuit 11.
A count operation continuation signal is output to the counter 10 based on the read operation continuation signal from. The counter 10 outputs a read field signal to the memory read control circuit 8 in accordance with the input count operation continuation signal.

・6. Since this readout field signal is reproducing a digital video signal at 1/4-times speed, it is read out from the field memory 4 four times and then switched to the readout of field 5 to control the memory readout control circuit 8. do. In this way, image data is read out from the memory in sequence according to the reproduction speed: field 4, field 5, field 6, field 7, field 4, and reproduced images are output in sequence.

Next, the operation at the time of stopping from 174 times speed playback will be explained with reference to FIG. In FIG. 3, a indicates an operating state signal, b indicates a write state of the field memories 4 to 7, and C indicates a read state.

The operating state signal a is output from the system control circuit shown in FIG. 1 and input to the field detector 1. The field detector 1 detects passage of all data in the field of the digital video signal being written to the field memory 7, and in accordance with the stop signal shown in FIG. 3a, stops the operation of the counter 2 in FIG. Stops all write operations. At this time, all image data for three fields is stored in the field memories 5 to 7, and the operation does not stop in the middle of field writing, until the field detector 1 in Figure 1 determines to stop. Operation continues. Similarly, since the tracks on the tape are scanned until all the fields written in the field memory 7 are reproduced, there is no interruption in the reproduction signal to be written in the memory. Therefore, the digital video signals to the field memories 4 to 7 are in the state shown in FIG.

As shown in FIG. 3C, signals are read from the memory when data is being written to the field memory 5, to the field memory 7, and when data is being written to the field memory 6, to the field memory 4 and field memory 7. When data is being written, the field memory 5 is repeatedly written. While reading the field memory 5, the third
Although the stop signal shown in FIG. 1A is input from the system control circuit 11 to the field detector 9, the counter 10 in FIG. 1 is not stopped, and the memory read control circuit 8 in FIG. 1 continues reading the memory. And the field detector 9
When the latest reproduction signal from the field memory 7 is detected, the operation of the counter 10 is stopped and the transfer to the field memory 4 is stopped.

At this time, the memory read control circuit 8 continues reading from the field memory 7. When the operating signal is switched from stop to 1174 times playback as shown in FIG. 3a, this signal is input from the system control circuit 11 to the field detectors 1 and 9. The field detector 1 distinguishes between the signal in the field memory 7 and the signal in the field 6 from the input 1174 times speed signal and the reproduced digital video signal, prohibits writing to the field memory 7, and determines what should be written to the field memory 6. The counter 2 is controlled to write the reproduced digital video signal.

In the field detection 9, the reproduced digital video signal written in the field memory 7 is read out, but since the 1174 times speed signal is input from the system control circuit 11, the counter 10 is not operated and the reproduced digital video signal is read out from the field memory 7. Continue reading until the writing of F.9. yield memory 4 begins. At the start of writing to the field memory 4, the field detector 1 sends a start signal to the system control circuit 11, from which the field detector 9 sends an operation signal to the counter 10, and the memory read control circuit 8 starts writing the field memory 6. Reading begins. Here, Figure 3, c
As shown in the figure, the counters 2 and 10 operate in the order of field memories 4, 5, and 6.7 when the reproduction operation is in the positive direction, and in the order of field memories 7, 6.5, and 7 when the reproduction operation is in the negative direction.
The memory write control circuit 3 and the memory read control circuit 8 are controlled to read and write in the order of .degree.4.

In this way, each memory starts reading after writing is completed, so there is no possibility of read/write signals colliding. Further, in this embodiment, one field is divided into six recording tracks, but since read and write fields are detected, the same effect can be obtained even if the division ratio is changed. Furthermore, even when the signal scanning locus does not cross the signal recording track, the same effect can be obtained by performing the above control.

・10・Furthermore, the same effect can be obtained even if the memory used is a number other than 4 fields. Further, the same effect can be obtained by performing the above control in variable speed playback other than ±174 times speed playback.

〔Effect of the invention〕

As described above, according to the present invention, by controlling reading and writing of the memory using a field detector, the reproduced image output during variable speed reproduction can be composed of the same field. Furthermore, since the field image read from memory is the latest signal that was last played back and written to memory,
Since the positions of the image output and the recording medium match, editing points can be determined more precisely.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a memory control circuit according to an embodiment of the present invention, FIG. 2 is a recording format diagram used to explain the embodiment, and FIG. 3 is a time chart used to explain the embodiment. 1.9...Field detector 2.10...
···counter

Claims (1)

[Claims] 1. When reading and writing a reproduced digital video signal to and from a memory in a digital video signal recording and reproducing device, the signal written in the memory is read after a predetermined period, and when the writing is stopped, the most recent written signal is read. A memory control device characterized in that it operates continuously up to a signal.