JP3154905B2 - Video / audio recording / 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 video / audio recording / reproducing apparatus for recording / reproducing a digital video signal and a digital audio signal by compressing / expanding them using a semiconductor memory as a recording medium.

[0002]

2. Description of the Related Art Conventionally, semiconductor memories have been used as recording media for digital video signals and digital audio signals. In this case, to reduce the memory capacity, compression /
Decompression is essential.

However, when a digital video signal and a digital audio signal are compressed / expanded and recorded / reproduced in a semiconductor memory, the processing time required for signal compression / expansion differs between video and audio. A gap occurs between the sound and the sound, resulting in unnatural reproduction. this is,
This is a state where the so-called lip sync is deviated.

[0004]

As described above, a conventional video system in which a digital video signal and a digital audio signal are respectively compressed and written into a semiconductor memory, and the readout signal is decompressed and recorded / reproduced. In the audio recording / reproducing apparatus, the processing time required for signal compression / expansion differs between video and audio, so that a difference between the reproduced video and audio (hereinafter, referred to as lip sync) has occurred.

An object of the present invention is to provide a video / audio recording / reproducing apparatus capable of correcting a lip sync generated between a reproduced digital video signal and a reproduced digital audio signal. With the goal.

[0006]

According to the present invention, a digital video signal and a digital audio signal are compressed and written to a video recording memory and an audio recording memory, respectively, and the respective read signals are decompressed. In a video / audio recording / reproducing apparatus which processes and records / reproduces each signal, a timing information generating circuit for generating timing information at a fixed period; Timing information adding means for adding timing information generated by the timing information generating circuit at the same timing, and timing information detecting means for detecting timing information from the respective signals after the digital video signal and the digital audio signal are expanded. And the timing information detected from each signal by this means. The video signal recording memory so that the detected timing, respectively coincide, and comprises a comparison control means for controlling at least one of the read timing of the audio signal recording memory.

[0007]

In the video / audio recording / reproducing apparatus having the above configuration,
Timing information is added to the digital video signal and digital audio signal at the same timing before the compression processing, the timing information is detected after the expansion processing, the time difference is obtained, and the read timing of each memory is controlled so that this time difference disappears. I do. That is, since the video / audio reproduction signal is read from each memory so that the detection timings of the timing information coincide with each other, the lip sync is suppressed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows the configuration, in which a timing information generating circuit 11 generates timing information at a constant period, and the generated timing information is sent to additional circuits 121 and 122.

The adding circuit 121 adds timing information to the digital video signal.
, And is written into the video recording memory 141. The addition circuit 122 adds timing information to the digital audio signal, and its output is appropriately compressed by the compressor 132 and written to the audio recording memory 142.

The video recording memory 141 and the audio recording memory 142 are both set to a write mode when a recording control signal is given from the outside, and the compressors 131 and 1 are respectively set.
The video compression signal and the audio compression signal from 32 are written. Also, when a reproduction control signal is given, a read mode is set, and the written video compression signal and audio compression signal are read from designated locations.

The compressed video signal read from the video recording memory 141 is expanded by an expander 151 and output as a digital video reproduction signal. Also, a voice recording memory 1
The compressed audio signal read out from 42 is expanded by the expander 152 and output as a digital audio reproduction signal.

The digital video reproduction signal and the digital audio reproduction signal are output from a timing information detecting circuit 161,
162, where timing information added at the time of recording is detected. The detected timing information is input to the comparison control circuit 17 together. This comparison control circuit 17
Detects the time difference by comparing both timing information,
The reading timing of the memories 141 and 142 is controlled so that the time difference disappears.

That is, in the video / audio recording / reproducing apparatus having the above configuration, timing information is added to a video signal and an audio signal at the same timing before the compression processing, and after the decompression processing, the timing information is detected and the time difference is detected. Asked,
The read timing of the memories 141 and 142 is controlled so that the time difference disappears. That is, since the video / audio reproduction signal is read from the memories 141 and 142 so that the detection timings of the timing information coincide with each other, the lip sync is suppressed.

Therefore, according to the above configuration, even if the compression / expansion processing times of the video signal and the audio signal are different from each other, it is possible to correct the lip sync generated between the reproduction signals.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the readout timing of both the video signal recording memory and the audio signal recording memory is controlled, but it is generally taken into consideration that the compression / expansion processing of the video signal takes longer time. Alternatively, one of them may be controlled such that the readout timing on the audio signal side is delayed or the readout timing on the video signal side is advanced. Of course, if these processes are performed at the same time, the time difference can be increased. In addition, it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0016]

As described above, according to the present invention, it is possible to provide a video / audio recording / reproducing apparatus which can correct a lip sync generated between reproduced signals of a digital video signal and a digital audio signal.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a configuration of an embodiment of a video / audio recording / playback apparatus according to the present invention.

[Explanation of symbols]

11: timing information generation circuit, 121, 122: additional circuit, 131, 132: compressor, 141: video signal recording memory, 142: audio signal recording memory, 151, 1
52: expander, 161, 162: timing information detection circuit, 17: comparison control circuit.

Claims (4)

(57) [Claims] 1. A video / audio recording system for compressing a digital video signal and a digital audio signal, writing them in a video recording memory and an audio recording memory, and expanding / decompressing each read signal to record / reproduce each signal. In the reproducing apparatus, a timing information generating circuit for generating timing information at a constant period; and a timing information generated by the timing information generating circuit for each signal before compression processing of the digital video signal and the digital audio signal. A timing information adding means for adding the digital video signal and the digital audio signal, and a timing information detecting means for detecting timing information from each signal after expanding the digital video signal and the digital audio signal, and comparing the timing information detected from each signal by this means. The video signal so that the respective detection timings match. Recording memory, video / audio recording and reproducing apparatus for and a comparison control means for controlling at least one of the read timing of the audio signal recording memory. 2. The video / audio recording / reproducing apparatus according to claim 1, wherein said comparison control means makes the read timing of the audio signal side later than that of the video signal side. 3. The video / audio recording / reproducing apparatus according to claim 1, wherein said comparison control means sets the readout timing on the video signal side earlier than on the audio signal side. 4. The comparison control means according to claim 1, wherein the read timing on the audio signal side is made later than that on the video signal side, and the read timing on the video signal side is made earlier than the read timing on the audio signal side. Video / audio recording and playback device.