v2:
- cover letter
- testing methodology
- Signed-off-by
V4L2 has support for hierarchical P frames using the
V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING* controls. This allows for
specifing P frame references needed for temporal scalability. Encoding a
single stream with a single layer allows for the layer to be dropped and
the stream to be decoded without artifacts.
ChromeOS is planning to use this feature for the L1T2 web standard[1].
This allows video conferencing apps to encode once for a clients with
different performance/bandwidth capabilities.
The ChromeOS test framework ("tast") was used to verify that no
regressions are present. This was done on SC7180 ("trogdor").
Verification of the added controls was done with a bitstream analyser to
make sure that reference frame management is correct.
[1]: https://www.w3.org/TR/webrtc-svc/#L1T2*
