linux-kernel - [PATCH v1 02/24] media: doc: Document dual use of H.264 pic_num/frame

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20220328195936.82552-3-nicolas.dufresne@collabora.com>
Date:   Mon, 28 Mar 2022 15:59:14 -0400
From:   Nicolas Dufresne <nicolas.dufresne@...labora.com>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     kernel@...labora.com, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v1 02/24] media: doc: Document dual use of H.264 pic_num/frame_num

These two fields needs documentation as they have dual meaning. It is also
confusing since pic_num is a derived value from frame_num, so this should
help application developpers. If we ever need to make a V2 of this API, I
would suggest to remove pic_num entirely.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>
---
 .../media/v4l/ext-ctrls-codec-stateless.rst            | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst
index 6541e4c32b26..f634f20bcfbe 100644
--- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst
+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst
@@ -649,10 +649,16 @@ Stateless Codec Control ID
         :c:type:`timeval` in struct :c:type:`v4l2_buffer` to a __u64.
     * - __u32
       - ``pic_num``
-      -
+      - For short term reference, this should match the derived value PicNum
+	(8-28) and for long term references it should match the derived value
+	LongTermPicNum (8-29). Note that pic_num is the same as FrameNumWrap
+	for frame decoding.
     * - __u16
       - ``frame_num``
-      -
+      - For short term references, this should match the frame_num value from
+	the slice header syntax (the driver will wrap the value if neeeded). For
+	long term references, this should be set to the value of
+	long_term_frame_idx describes in the dec_ref_pic_marking() syntax.
     * - __u8
       - ``fields``
       - Specifies how the DPB entry is referenced. See :ref:`Reference Fields <h264_ref_fields>`
-- 
2.34.1