gst_pad_get_pad_template_caps() returns a reference which is unreferenced,
so creating a copy using gst_caps_copy() results in a reference leak.
Also remove the incorrect comment to avoid confusion in the future.
Fixes https://bugzilla.gnome.org/show_bug.cgi?id=734533
gst_amc_color_format_copy will copy in/out a frame resides at a
GstAmcBuffer. Lots of codes in gst_amc_video_*_fill_buffer are moved to
this new function.
Some hack logic needs also to be present in create_src|sink_caps, for
working around some broken codecs. These hacks are hidden
in color_format/video_format conversion -- the prototypes of these
functions are also changed to include more args for hack judgement.
Also in case of multi-color_formats mapped to one video_format, then
map that video_format back will not give the original color_format, which
causes gst_amc_codec_configure failed with something like
'does not support color format N'.
The new prototype involves with GstAmcCodecInfo and mime, which
ensures the converted color_format is supported by the codec.
A COLOR_FormatYCbYCr to GST_VIDEO_FORMAT_YUY2 mapping is also added, in
order to work around bugs in OMX.k3.video.decoder.avc(which incorrectly
reports supporting COLOR_FormatYCbYCr, which is actually
COLOR_FormatYUV420SemiPlanar). There are already hacks for this in
gst_amc_video_format_to_color_format, gst_amc_color_format_to_video_format
and gst_amc_color_format_info_set, but the codec will still not work(be
ignored because of "has unknown color formats") without adding this mapping.
