Re: [PATCH] media: videobuf2: add V4L2_BUF_FLAG_CODECCONFIG flag
From: Nicolas Dufresne <hidden>
Date: 2022-07-04 15:53:00
Also in:
linux-media, lkml
Le mardi 28 juin 2022 à 10:19 +0800, Ming Qian a écrit :
By setting the V4L2_BUF_FLAG_CODECCONFIG flag, user-space should be able to hint decoder the vb2 only contains codec config header, but does not contain any frame data. It's only used for parsing header, and can't be decoded.
This is copied from OMX specification. I think we we import this, we should at least refer to the original.
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Current, it's usually used by android. Signed-off-by: Ming Qian <ming.qian@nxp.com> --- Documentation/userspace-api/media/v4l/buffer.rst | 9 +++++++++ include/uapi/linux/videodev2.h | 2 ++ 2 files changed, 11 insertions(+)diff --git a/Documentation/userspace-api/media/v4l/buffer.rst b/Documentation/userspace-api/media/v4l/buffer.rst index 4638ec64db00..acdc4556f4f4 100644 --- a/Documentation/userspace-api/media/v4l/buffer.rst +++ b/Documentation/userspace-api/media/v4l/buffer.rst@@ -607,6 +607,15 @@ Buffer Flags the format. Any subsequent call to the :ref:`VIDIOC_DQBUF <VIDIOC_QBUF>` ioctl will not block anymore, but return an ``EPIPE`` error code. + * .. _`V4L2-BUF-FLAG-CODECCONFIG`: + + - ``V4L2_BUF_FLAG_CODECCONFIG`` + - 0x00200000 + - This flag may be set when the buffer only contains codec config + header, but does not contain any frame data. Usually the codec config + header is merged to the next idr frame, with the flag + ``V4L2_BUF_FLAG_KEYFRAME``, but there is still some scenes that will + split the header and queue it separately.
I think the documentation is clear. Now, if a driver uses this, will existing userland (perhaps good to check GStreamer, FFMPEG and Chromium ?) will break ? So we need existing driver to do this when flagged to, and just copy/append when the userland didn't opt-in that feature ?
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* .. _`V4L2-BUF-FLAG-REQUEST-FD`: - ``V4L2_BUF_FLAG_REQUEST_FD``diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h index 5311ac4fde35..8708ef257710 100644 --- a/include/uapi/linux/videodev2.h +++ b/include/uapi/linux/videodev2.h@@ -1131,6 +1131,8 @@ static inline __u64 v4l2_timeval_to_ns(const struct timeval *tv) #define V4L2_BUF_FLAG_TSTAMP_SRC_SOE 0x00010000 /* mem2mem encoder/decoder */ #define V4L2_BUF_FLAG_LAST 0x00100000 +/* Buffer only contains codec header */ +#define V4L2_BUF_FLAG_CODECCONFIG 0x00200000 /* request_fd is valid */ #define V4L2_BUF_FLAG_REQUEST_FD 0x00800000
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