The present invention relates to a video signal transmitting system, and is suitably applied to a case where moving picture signals are transmitted.
In the so-called video transmitting system, such as a television conference system and television telephone system, video signals representing moving pictures are conventionally sent to a remote destination. The transmission efficiency of significant information is enhanced by efficiently using the transmission capacity of the transmission channel.
For this purpose, the transmitting unit does not send all of the sequential frame pictures but performs a so-called frame dropping processing of the frame pictures such as to remove predetermined frames and then transmits the video signals.
In the receiving unit, motion vectors are received from the transmitting unit in place of the video signals of the removed frames, and the original video signals are reconstructed by interpolating the frame pictures, which have undergone frame dropping processing, by using motion vectors with reference to information in frame pictures before and after them, the motion vectors being transmitted from the transmitting unit in place of the video signals of the frames dropped (Patent Laid-open Publication No. 60 (1985)-28392).
According to this technique, it is theoretically sufficient to transmit information of motion vectors in place of information in frame pictures which have been dropped, the former possessing a smaller amount than the latter. Thus, it is considered that the technique efficiently sends significant information of the video signals.
Accordingly, the more frames that are dropped, the more efficiently video signals are transmitted
When video signals practically undergo high efficiency coding processing and then are recorded on a recording medium, such as a compact disc, errors cannot however be prevented from taking place. Moreover, video signals are also reproduced in reverse mode and random accessed and hence when a large amount of frames are dropped, it is difficult to reproduce video signals with high quality.