This improves behaviour with drivers which do not support packed
headers, such as AMD VCE on mesa/gallium.
(cherry picked from commit 892bbbcdc171ff0d08d69636a240ffb95f54243c)
This allows better checking of capabilities and will make it easier
to add more functionality later.
It also commonises some duplicated code around rate control setup
and adds more comments explaining the internals.
(cherry picked from commit 80a5d05108cb218e8cd2e25c6621a3bfef0a832e)
These are all trivial to merge.
* commit '92fdea37477b5a2d1329e5ef0773e24473fa8f12':
vaapi_h265: Add -qp option, use it to replace use of -global_quality
vaapi_h265: Add constant-bitrate encode support
vaapi_h264: Add encode quality option (for quality-speed tradeoff)
vaapi_h264: Add -qp option, use it to replace use of -global_quality
vaapi_encode: Add support for codec-local options
vaapi_h264: Add constant-bitrate encode support
vaapi_encode: Refactor slightly to allow easier setting of global options
Merged-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
