> > A quick Google implies that NVidia already has a stateful V4L2 M2M > driver in their vendor kernel. Other than the strange choice of device > node name (/dev/nvhost-nvdec), the details at [3] make it look like a > normal V4L2 M2M decoder that has a good chance of working against > h264_v4l2m2m.
Not only does it have a strange node name, it also uses two nodes. One for decoding, another for converting. Capture plane of the decoder stores frames in V4L2_PIX_FMT_NV12M format. Converter able to convert it to a different format[1]. Could you point me at documentation of Pi V4L2 spec? [1] https://docs.nvidia.com/jetson/l4t-multimedia/group__V4L2Conv.html Andrii On Mon, Jul 12, 2021 at 6:02 AM Dave Stevenson < dave.steven...@raspberrypi.com> wrote: > On Sat, 10 Jul 2021 at 00:56, Brad Hards <br...@frogmouth.net> wrote: > > > > On Saturday, 10 July 2021 8:53:27 AM AEST Andrii wrote: > > > I am working on porting a Kodi player to an NVidia Jetson Nano device. > I've > > > been developing a decoder for quite some time now, and realized that > the > > > best approach would be to have it inside of ffmpeg, instead of > embedding > > > the decoder into Kodi as it heavily relies on FFMPEG. Just wondering if > > > there is any effort in making FFMPEG suppring M2M V4L devices ? > > > > > https://git.ffmpeg.org/gitweb/ffmpeg.git/blob_plain/HEAD:/libavcodec/v4l2_m2m.c[1] > > > > I guess that would be the basis for further work as required to meet > your needs. > > Do note that there are 2 V4L2 M2M decoder APIs - the stateful API[1] , > and the stateless API [2]. They differ in the amount of bitstream > parsing and buffer management that the driver implements vs expecting > the client to do. > > The *_v4l2m2m drivers within FFMPEG support the stateful API (ie the > kernel driver has bitstream parsing). For Raspberry Pi we use that to > support the (older) H264 implementation, and FFMPEG master does that > very well. > > The Pi HEVC decoder uses the V4L2 stateless API. Stateless HEVC > support hasn't been merged to the mainline kernel as yet, so there are > downstream patches to support that. > > A quick Google implies that NVidia already has a stateful V4L2 M2M > driver in their vendor kernel. Other than the strange choice of device > node name (/dev/nvhost-nvdec), the details at [3] make it look like a > normal V4L2 M2M decoder that has a good chance of working against > h264_v4l2m2m. > > [1] > https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/dev-decoder.html > [2] > https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/dev-stateless-decoder.html > [3] https://docs.nvidia.com/jetson/l4t-multimedia/group__V4L2Dec.html > > Dave > > > Brad > > > > -------- > > [1] > https://git.ffmpeg.org/gitweb/ffmpeg.git/blob_plain/HEAD:/libavcodec/v4l2_m2m.c > > _______________________________________________ > > ffmpeg-devel mailing list > > ffmpeg-devel@ffmpeg.org > > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > > > To unsubscribe, visit link above, or email > > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
