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Date: Mon, 12 Aug 2019 12:11:45 +0200
From: Hans Verkuil <hverkuil@...all.nl>
To: Ezequiel Garcia <ezequiel@...labora.com>,
linux-media@...r.kernel.org
Cc: kernel@...labora.com,
Nicolas Dufresne <nicolas.dufresne@...labora.com>,
Tomasz Figa <tfiga@...omium.org>,
linux-rockchip@...ts.infradead.org,
Heiko Stuebner <heiko@...ech.de>,
Jonas Karlman <jonas@...boo.se>,
Philipp Zabel <p.zabel@...gutronix.de>,
Boris Brezillon <boris.brezillon@...labora.com>,
Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
Alexandre Courbot <acourbot@...omium.org>,
fbuergisser@...omium.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 04/11] media: uapi: h264: Add the concept of start code
On 8/8/19 12:34 PM, Ezequiel Garcia wrote:
> 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 <ezequiel@...labora.com>
> ---
> Changes in v4:
> * New patch.
> ---
> .../media/uapi/v4l/ext-ctrls-codec.rst | 31 +++++++++++++++++++
> drivers/media/v4l2-core/v4l2-ctrls.c | 9 ++++++
> include/media/h264-ctrls.h | 6 ++++
> 3 files changed, 46 insertions(+)
>
> diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> index ea0455957149..94fd3a9b8b9e 100644
> --- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> +++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> @@ -2062,6 +2062,37 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
> The OUTPUT buffer should contain all slices needed to decode the
> frame/field.
>
> +``V4L2_CID_MPEG_VIDEO_H264_STARTCODE (enum)``
> + Specifies the H264 slice start code expected for each slice.
> + This control shall e used to complement V4L2_PIX_FMT_H264_SLICE
e -> be
> + pixel format. 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_startcode
> +
> +.. cssclass:: longtable
> +
> +.. flat-table::
> + :header-rows: 0
> + :stub-columns: 0
> + :widths: 1 1 2
> +
> + * - ``V4L2_MPEG_VIDEO_H264_NO_STARTCODE``
> + - 0
> + - Selecting this value specifies that H264 slices are passed
> + to the driver without any start code.
> + Bla.
Bla?
> + * - ``V4L2_MPEG_VIDEO_H264_ANNEX_B_STARTCODE``
> + - 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.
> +
I had the impression that it is more common to require startcodes. If that's
indeed the case, shouldn't this have value 0 instead of 1?
> .. _v4l2-mpeg-mpeg2:
>
> ``V4L2_CID_MPEG_VIDEO_MPEG2_SLICE_PARAMS (struct)``
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
> index c3194299bfac..01fddb4ec640 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
> @@ -407,6 +407,11 @@ const char * const *v4l2_ctrl_get_menu(u32 id)
> "Frame-Based",
> NULL,
> };
> + static const char * const h264_start_code[] = {
> + "No Start Code",
> + "Annex B Start Code",
> + NULL,
> + };
> static const char * const mpeg_mpeg2_level[] = {
> "Low",
> "Main",
> @@ -640,6 +645,8 @@ const char * const *v4l2_ctrl_get_menu(u32 id)
> return h264_fmo_map_type;
> case V4L2_CID_MPEG_VIDEO_H264_DECODING_MODE:
> return h264_decoding_mode;
> + case V4L2_CID_MPEG_VIDEO_H264_STARTCODE:
> + return h264_start_code;
> case V4L2_CID_MPEG_VIDEO_MPEG2_LEVEL:
> return mpeg_mpeg2_level;
> case V4L2_CID_MPEG_VIDEO_MPEG2_PROFILE:
> @@ -860,6 +867,7 @@ const char *v4l2_ctrl_get_name(u32 id)
> case V4L2_CID_MPEG_VIDEO_H264_SLICE_PARAMS: return "H264 Slice Parameters";
> case V4L2_CID_MPEG_VIDEO_H264_DECODE_PARAMS: return "H264 Decode Parameters";
> case V4L2_CID_MPEG_VIDEO_H264_DECODING_MODE: return "H264 Decoding Mode";
> + case V4L2_CID_MPEG_VIDEO_H264_STARTCODE: return "H264 Start Code";
> case V4L2_CID_MPEG_VIDEO_MPEG2_LEVEL: return "MPEG2 Level";
> case V4L2_CID_MPEG_VIDEO_MPEG2_PROFILE: return "MPEG2 Profile";
> case V4L2_CID_MPEG_VIDEO_MPEG4_I_FRAME_QP: return "MPEG4 I-Frame QP Value";
> @@ -1229,6 +1237,7 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
> case V4L2_CID_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE:
> case V4L2_CID_MPEG_VIDEO_H264_FMO_MAP_TYPE:
> case V4L2_CID_MPEG_VIDEO_H264_DECODING_MODE:
> + case V4L2_CID_MPEG_VIDEO_H264_STARTCODE:
> case V4L2_CID_MPEG_VIDEO_MPEG2_LEVEL:
> case V4L2_CID_MPEG_VIDEO_MPEG2_PROFILE:
> case V4L2_CID_MPEG_VIDEO_MPEG4_LEVEL:
> diff --git a/include/media/h264-ctrls.h b/include/media/h264-ctrls.h
> index e6c510877f67..31555c99f64a 100644
> --- a/include/media/h264-ctrls.h
> +++ b/include/media/h264-ctrls.h
> @@ -27,6 +27,7 @@
> #define V4L2_CID_MPEG_VIDEO_H264_SLICE_PARAMS (V4L2_CID_MPEG_BASE+1003)
> #define V4L2_CID_MPEG_VIDEO_H264_DECODE_PARAMS (V4L2_CID_MPEG_BASE+1004)
> #define V4L2_CID_MPEG_VIDEO_H264_DECODING_MODE (V4L2_CID_MPEG_BASE+1005)
> +#define V4L2_CID_MPEG_VIDEO_H264_STARTCODE (V4L2_CID_MPEG_BASE+1006)
>
> /* enum v4l2_ctrl_type type values */
> #define V4L2_CTRL_TYPE_H264_SPS 0x0110
> @@ -41,6 +42,11 @@ enum v4l2_mpeg_video_h264_decoding_mode {
> V4L2_MPEG_VIDEO_H264_FRAME_BASED_DECODING,
> };
>
> +enum v4l2_mpeg_video_h264_start_code {
> + V4L2_MPEG_VIDEO_H264_NO_STARTCODE,
> + V4L2_MPEG_VIDEO_H264_ANNEX_B_STARTCODE,
> +};
> +
> #define V4L2_H264_SPS_CONSTRAINT_SET0_FLAG 0x01
> #define V4L2_H264_SPS_CONSTRAINT_SET1_FLAG 0x02
> #define V4L2_H264_SPS_CONSTRAINT_SET2_FLAG 0x04
>
Regards,
Hans
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