Original commit message from CVS:
* ext/ffmpeg/gstffmpegcodecmap.c: (gst_ffmpeg_formatid_to_caps),
(gst_ffmpeg_formatid_get_codecids):
Added proper mime types for mxf and gxf formats.
Added known configuration for asf muxer. Implies allowing the ffmpeg asf
muxer to take WMV and WMA.
* ext/ffmpeg/gstffmpegdec.c: (gst_ffmpegdec_chain):
Most demuxers/formats don't give keyframe information on encoded
audio streams. We therefore don't discard them, and use the clipping
functionnality to drop the decoded buffers we didn't need.