On 01/22/2019 07:26 AM, Alexandre Courbot wrote: > Documents the protocol that user-space should follow when > communicating with stateless video decoders. > > The stateless video decoding API makes use of the new request and tags > APIs. While it has been implemented with the Cedrus driver so far, it > should probably still be considered staging for a short while. > > Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxxxx> > --- > Changes since v1: > > * Use timestamps instead of tags to reference frames, > * Applied Paul's suggestions to not require one frame worth of data per OUTPUT > buffer > > One of the effects of requiring sub-frame units to be submitted per request is > that the stateless decoders are not exactly "stateless" anymore: if a frame is > made of several slices, then the decoder must keep track of the buffer in which > the current frame is being decoded between requests, and all the slices for the > current frame must be submitted before we can consider decoding the next one. > > Also if we decide to force clients to submit one slice per request, then doesn't > some of the H.264 controls need to change? For instance, in the current v2 > there is still a v4l2_ctrl_h264_decode_param::num_slices member. It is used in > Chromium to specify the number of slices given to the > V4L2_CID_MPEG_VIDEO_H264_SLICE_PARAMS control, but is apparently ignored by the > Cedrus driver. Maxime, can you comment on this? > > Documentation/media/uapi/v4l/dev-codec.rst | 5 + > .../media/uapi/v4l/dev-stateless-decoder.rst | 378 ++++++++++++++++++ > 2 files changed, 383 insertions(+) > create mode 100644 Documentation/media/uapi/v4l/dev-stateless-decoder.rst > Thank you! I have uploaded a version of the V4L2 spec with this and the two older stateful codec patches applied: https://hverkuil.home.xs4all.nl/codec-api/uapi/v4l/dev-codec.html Regards, Hans
