From 8255b4d21967e978f96a87cf032471f527149794 Mon Sep 17 00:00:00 2001
From: Philipp Zabel
Date: Tue, 10 Sep 2019 07:20:30 -0300
Subject: media: uapi: h264: clarify V4L2_PIX_FMT_H264_SLICE format
Document that the slice headers must be included for the benefit of
decoders that parse them (partially) in hardware, and that the start
code is optional. Add a link to the ITU-T Rec. H.264 specification
section that describes the slice format.
Signed-off-by: Philipp Zabel
Signed-off-by: Hans Verkuil
Signed-off-by: Mauro Carvalho Chehab
---
Documentation/media/uapi/v4l/pixfmt-compressed.rst | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/Documentation/media/uapi/v4l/pixfmt-compressed.rst b/Documentation/media/uapi/v4l/pixfmt-compressed.rst
index 292fdc116c77..55d8d690f22f 100644
--- a/Documentation/media/uapi/v4l/pixfmt-compressed.rst
+++ b/Documentation/media/uapi/v4l/pixfmt-compressed.rst
@@ -61,10 +61,10 @@ Compressed Formats
- ``V4L2_PIX_FMT_H264_SLICE``
- '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`).
+ - H264 parsed slice data, including slice headers, either with or
+ without the start code, 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`).
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.
@@ -80,6 +80,10 @@ Compressed Formats
appropriate number of macroblocks to decode a full
corresponding frame to the matching capture buffer.
+ The syntax for this format is documented in :ref:`h264`, section
+ 7.3.2.8 "Slice layer without partitioning RBSP syntax" and the following
+ sections.
+
.. note::
This format is not yet part of the public kernel API and it
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