| 摘要 |
An editing system handles offspeed and full speed playback of long GOP compressed video information by having one decoder for full-speed or slower forward playback of long GOP compressed motion video information, and a second single-frame, stateless decoder for use for off-speed playback. When compressed data is read from a file, the compressed data for at least one complete group of pictures is read into a buffer, herein called a compressed data buffer. A data structure, herein called a frame ring, is constructed to describe each image in the compressed data buffer. The single-frame, stateless decoder receives decompression parameters in addition to the compressed data for each image from this buffer. If the compressed data is a B-frame or P-frame, then uncompressed data for any other images (i.e., reference frames) required by the decoder to decompress the frame also is input to the single-frame, stateless decoder. If the uncompressed data for the reference frames is not already in a cache, these reference frames are decompressed and the uncompressed data for the reference frames as used by the decoder is stored in the cache prior to the decompression of the B-frame or P-frame.
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