media: pixfmt: Add H264_SLICE_RAW format documentation

The H264_SLICE_RAW format introduced before is meant for stateless
decoders that will need the H264 parsed slice data without the start code.

Let's document it.

Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

diff --git a/Documentation/media/uapi/v4l/pixfmt-compressed.rst b/Documentation/media/uapi/v4l/pixfmt-compressed.rst
index 6c961cf..4b701fc 100644 (file)
--- a/Documentation/media/uapi/v4l/pixfmt-compressed.rst
+++ b/Documentation/media/uapi/v4l/pixfmt-compressed.rst
@@ -52,6 +52,31 @@ Compressed Formats
       - ``V4L2_PIX_FMT_H264_MVC``
       - 'M264'
       - H264 MVC video elementary stream.
+    * .. _V4L2-PIX-FMT-H264-SLICE-RAW:
+
+      - ``V4L2_PIX_FMT_H264_SLICE_RAW``
+      - 'S264'
+      - H264 parsed slice data, without the start code and as
+       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`).
+       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``,
+       ``V4L2_CID_MPEG_VIDEO_H264_SCALING_MATRIX``,
+       ``V4L2_CID_MPEG_VIDEO_H264_SLICE_PARAMS`` and
+       ``V4L2_CID_MPEG_VIDEO_H264_DECODE_PARAMS`` controls.  See the
+       :ref:`associated Codec Control IDs <v4l2-mpeg-h264>`.  Exactly
+       one output and one capture buffer must be provided for use
+       with this pixel format. The output buffer must contain the
+       appropriate number of macroblocks to decode a full
+       corresponding frame to the matching capture buffer.
+
+       .. note::
+
+          This format is not yet part of the public kernel API and it
+          is expected to change.
+
     * .. _V4L2-PIX-FMT-H263:
 
       - ``V4L2_PIX_FMT_H263``