decoder: introduce lists of units to decode before/after frame.
Theory of operations: all units marked as "slice" are moved to the "units" list. Since this list only contains slice data units, the prev_slice pointer was removed. Besides, we now maintain two extra lists of units to be decoded before or after slice data units. In particular, all units in the "pre_units" list will be decoded before GstVaapiDecoder::start_frame() is called and units in the "post_units" list will be decoded after GstVaapiDecoder::end_frame() is called.
Showing with 73 additions and 42 deletions