decoder: get rid of GstAdapter-based infrastructure
@gb
Submitted by Gwenole Beauchesne Link to original bug (#732665)
Description
The use of GstAdapter in libgstvaapi is not very convenient without explicit specification of the source buffers granularity (frame, packet, random). More specifically, looking for start/sync codes could be more efficient if simple list of buffers was maintained. i.e. fast scan_for_start_codes() + minor additional care needed at boundaries.