This adds support for the AverMedia C985 encoder (which is available on
C985 capture cards) as well as the C353 hardware encoder (which is
currently available on the X99S Gaming 9 motherboards).
These encoders have some limitations, such as limited resolutions
(1280x720 and 1024x768), a max GOP size of 30, and the encoder format
only supports YV12, which requires conversion if the current output
format isn't the same. The C985 and C353 encoders seem to be pretty
much identical, although it seems like the C353 has a bit more efficient
encoding.
I don't believe these are really suitable for streaming, as they do not
really have the encoding efficiency needed to stream at lower bitrates,
and seem to only support variable bitrate. However, for recording these
encoders are quite nice to have available, and work quite well.
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