On 10/1/19 12:27 AM, Jernej Škrabec wrote: > Dne ponedeljek, 30. september 2019 ob 10:10:48 CEST je Hans Verkuil > napisal(a): >> On 9/29/19 10:00 PM, Jernej Skrabec wrote: >>> This series adds support for decoding multi-slice H264 frames along with >>> support for V4L2_DEC_CMD_FLUSH and V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF. >>> >>> Code was tested by modified ffmpeg, which can be found here: >>> https://github.com/jernejsk/FFmpeg, branch mainline-test >>> It has to be configured with at least following options: >>> --enable-v4l2-request --enable-libudev --enable-libdrm >>> >>> Samples used for testing: >>> http://jernej.libreelec.tv/videos/h264/BA1_FT_C.mp4 >>> http://jernej.libreelec.tv/videos/h264/h264.mp4 >>> >>> Command line used for testing: >>> ffmpeg -hwaccel drm -hwaccel_device /dev/dri/card0 -i h264.mp4 -pix_fmt >>> bgra -f fbdev /dev/fb0 >>> >>> Please note that V4L2_DEC_CMD_FLUSH was not tested because I'm >>> not sure how. ffmpeg follows exactly which slice is last in frame >>> and sets hold flag accordingly. Improper usage of hold flag would >>> corrupt ffmpeg assumptions and it would probably crash. Any ideas >>> how to test this are welcome! >> >> It can be tested partially at least: if ffmpeg tells you it is the last >> slice, then queue the slice with the HOLD flag set, then call FLUSH >> afterwards. This should clear the HOLD flag again. In this case the queued >> buffer is probably not yet processed, so the flag is cleared before the >> decode job starts. >> >> You can also try to add a sleep before calling FLUSH to see what happens >> if the last queued buffer is already decoded. > > Ok, I tried following code: > https://github.com/jernejsk/FFmpeg/blob/flush_test/libavcodec/ > v4l2_request.c#L220-L233 > > But results are not good. It seems that out_vb in flush command is always NULL > and so it always marks capture buffer as done, which leads to kernel warnings. > > dmesg output with debugging messages is here: http://ix.io/1Ks8 > > Currently I'm not sure what is going on. Shouldn't be output buffer queued and > waiting to MEDIA_REQUEST_IOC_QUEUE which is executed after flush command as it > can be seen from ffmpeg code linked above? Argh, I forgot about the fact that this uses requests. The FLUSH should happen *after* the MEDIA_REQUEST_IOC_QUEUE ioctl. Otherwise it has no effect. As long as the request hasn't been queued, the buffer is also not queued to the driver, so out_vb will indeed be NULL. Sorry for the confusion. Regards, Hans > > Best regards, > Jernej > >> >> Regards, >> >> Hans >> >>> Thanks to Jonas for adjusting ffmpeg. >>> >>> Please let me know what you think. >>> >>> Best regards, >>> Jernej >>> >>> Changes from v1: >>> - added Rb tags >>> - updated V4L2_DEC_CMD_FLUSH documentation >>> - updated first slice detection in Cedrus >>> - hold capture buffer flag is set according to source format >>> - added v4l m2m stateless_(try_)decoder_cmd ioctl helpers >>> >>> Hans Verkuil (2): >>> vb2: add V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF >>> videodev2.h: add V4L2_DEC_CMD_FLUSH >>> >>> Jernej Skrabec (4): >>> media: v4l2-mem2mem: add stateless_(try_)decoder_cmd ioctl helpers >>> media: cedrus: Detect first slice of a frame >>> media: cedrus: h264: Support multiple slices per frame >>> media: cedrus: Add support for holding capture buffer >>> >>> Documentation/media/uapi/v4l/buffer.rst | 13 ++++++ >>> .../media/uapi/v4l/vidioc-decoder-cmd.rst | 10 +++- >>> .../media/uapi/v4l/vidioc-reqbufs.rst | 6 +++ >>> .../media/videodev2.h.rst.exceptions | 1 + >>> .../media/common/videobuf2/videobuf2-v4l2.c | 8 +++- >>> drivers/media/v4l2-core/v4l2-mem2mem.c | 35 ++++++++++++++ >>> drivers/staging/media/sunxi/cedrus/cedrus.h | 1 + >>> .../staging/media/sunxi/cedrus/cedrus_dec.c | 11 +++++ >>> .../staging/media/sunxi/cedrus/cedrus_h264.c | 11 ++++- >>> .../staging/media/sunxi/cedrus/cedrus_hw.c | 8 ++-- >>> .../staging/media/sunxi/cedrus/cedrus_video.c | 14 ++++++ >>> include/media/v4l2-mem2mem.h | 46 +++++++++++++++++++ >>> include/media/videobuf2-core.h | 3 ++ >>> include/media/videobuf2-v4l2.h | 5 ++ >>> include/uapi/linux/videodev2.h | 14 ++++-- >>> 15 files changed, 175 insertions(+), 11 deletions(-) > > > >
