From 8cae93e090113e46bd29a99c1727d8f13ea12fdf Mon Sep 17 00:00:00 2001 From: Ezequiel Garcia Date: Fri, 16 Aug 2019 13:01:25 -0300 Subject: media: uapi: h264: Add the concept of start code Stateless decoders have different expectations about the start code that is prepended on H264 slices. Add a menu control to express the supported start code types (including no start code). Drivers are allowed to support only one start code type, but they can support both too. Note that this is independent of the H264 decoding mode, which specifies the granularity of the decoding operations. Either in frame-based or slice-based mode, this new control will allow to define the start code expected on H264 slices. Signed-off-by: Ezequiel Garcia Tested-by: Philipp Zabel Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- Documentation/media/uapi/v4l/ext-ctrls-codec.rst | 33 ++++++++++++++++++++++ Documentation/media/uapi/v4l/pixfmt-compressed.rst | 5 ++-- 2 files changed, 36 insertions(+), 2 deletions(-) (limited to 'Documentation/media') diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst index 1da17a2c94d7..810ae9bb6f7c 100644 --- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst +++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst @@ -2076,6 +2076,39 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type - The OUTPUT buffer must contain all slices needed to decode the frame. The OUTPUT buffer must also contain both fields. +``V4L2_CID_MPEG_VIDEO_H264_START_CODE (enum)`` + Specifies the H264 slice start code expected for each slice. + This control is used as a modifier for V4L2_PIX_FMT_H264_SLICE + pixel format. Applications that support V4L2_PIX_FMT_H264_SLICE + are required to set this control in order to specify the start code + that is expected for the buffer. + Drivers may expose a single or multiple start codes, depending + on what they can support. + + .. note:: + + This menu control is not yet part of the public kernel API and + it is expected to change. + +.. c:type:: v4l2_mpeg_video_h264_start_code + +.. cssclass:: longtable + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + :widths: 1 1 2 + + * - ``V4L2_MPEG_VIDEO_H264_START_CODE_NONE`` + - 0 + - Selecting this value specifies that H264 slices are passed + to the driver without any start code. + * - ``V4L2_MPEG_VIDEO_H264_START_CODE_ANNEX_B`` + - 1 + - Selecting this value specifies that H264 slices are expected + to be prefixed by Annex B start codes. According to :ref:`h264` + valid start codes can be 3-bytes 0x000001 or 4-bytes 0x00000001. + .. _v4l2-mpeg-mpeg2: ``V4L2_CID_MPEG_VIDEO_MPEG2_SLICE_PARAMS (struct)`` diff --git a/Documentation/media/uapi/v4l/pixfmt-compressed.rst b/Documentation/media/uapi/v4l/pixfmt-compressed.rst index d666eb51741a..493b6020107d 100644 --- a/Documentation/media/uapi/v4l/pixfmt-compressed.rst +++ b/Documentation/media/uapi/v4l/pixfmt-compressed.rst @@ -60,8 +60,9 @@ Compressed Formats extracted from the H264 bitstream. This format is adapted for stateless video decoders that implement an H264 pipeline (using the :ref:`mem2mem` and :ref:`media-request-api`). - This pixelformat has a modifier that must be set at least once - through the ``V4L2_CID_MPEG_VIDEO_H264_DECODE_MODE`` control. + This pixelformat has two modifiers that must be set at least once + through the ``V4L2_CID_MPEG_VIDEO_H264_DECODE_MODE`` + and ``V4L2_CID_MPEG_VIDEO_H264_START_CODE`` controls. In addition, metadata associated with the frame to decode are required to be passed through the ``V4L2_CID_MPEG_VIDEO_H264_SPS``, ``V4L2_CID_MPEG_VIDEO_H264_PPS``, -- cgit v1.2.3-70-g09d2