Re: [PATCH v4] media: v4l2-ctrl: add control for long term reference.
From: Hans Verkuil
Date: Wed Dec 02 2020 - 08:49:39 EST
On 01/12/2020 09:13, Dikshita Agarwal wrote:
> Long Term Reference (LTR) frames are the frames that are encoded
> sometime in the past and stored in the DPB buffer list to be used
> as reference to encode future frames.
> This change adds controls to enable this feature.
>
> Signed-off-by: Dikshita Agarwal <dikshita@xxxxxxxxxxxxxx>
> ---
> .../userspace-api/media/v4l/ext-ctrls-codec.rst | 18 ++++++++++++++++++
> drivers/media/v4l2-core/v4l2-ctrls.c | 14 ++++++++++++++
> include/uapi/linux/v4l2-controls.h | 3 +++
> 3 files changed, 35 insertions(+)
>
> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> index 3b86959..40634f8 100644
> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> @@ -4450,3 +4450,21 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
> - Selecting this value specifies that HEVC slices are expected
> to be prefixed by Annex B start codes. According to :ref:`hevc`
> valid start codes can be 3-bytes 0x000001 or 4-bytes 0x00000001.
> +
> +``V4L2_CID_MPEG_VIDEO_LTR_COUNT (integer)``
> + Specifies the number of Long Term Reference (LTR) frames encoder needs
> + to generate or keep. This is applicable to H264 and HEVC encoder.
> +
> +``V4L2_CID_MPEG_VIDEO_FRAME_LTR_INDEX (integer)``
> + The current frame is marked as a Long Term Reference (LTR) frame
> + and given this LTR index which ranges from 0 to LTR_COUNT-1.
> + This is applicable to H264 and HEVC encoder and can be applied using
> + Request Api.
> + Source Rec. ITU-T H.264 (06/2019); Table 7.9
> +
> +``V4L2_CID_MPEG_VIDEO_USE_LTR_FRAMES (bitmask)``
> + Specifies the Long Term Reference (LTR) frame(s) to be used for
> + encoding the current frame.
> + This provides a bitmask which consists of bits [0, LTR_COUNT-1].
> + This is applicable to H264 and HEVC encoder and can be applied using
> + Request Api.
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
> index e5b726f..0b81b39 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
> @@ -958,6 +958,9 @@ const char *v4l2_ctrl_get_name(u32 id)
> case V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE: return "Vertical MV Search Range";
> case V4L2_CID_MPEG_VIDEO_REPEAT_SEQ_HEADER: return "Repeat Sequence Header";
> case V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME: return "Force Key Frame";
> + case V4L2_CID_MPEG_VIDEO_LTR_COUNT: return "LTR Count";
> + case V4L2_CID_MPEG_VIDEO_FRAME_LTR_INDEX: return "frame LTR index";
"Frame LTR Index"
> + case V4L2_CID_MPEG_VIDEO_USE_LTR_FRAMES: return "Use LTR Frame(s)";
Just: "Use LTR Frames". No '(s)'.
> case V4L2_CID_MPEG_VIDEO_MPEG2_SLICE_PARAMS: return "MPEG-2 Slice Parameters";
> case V4L2_CID_MPEG_VIDEO_MPEG2_QUANTIZATION: return "MPEG-2 Quantization Matrices";
> case V4L2_CID_MPEG_VIDEO_FWHT_PARAMS: return "FWHT Stateless Parameters";
> @@ -1273,6 +1276,17 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
> case V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE:
> *type = V4L2_CTRL_TYPE_INTEGER;
> break;
> + case V4L2_CID_MPEG_VIDEO_LTR_COUNT:
> + *type = V4L2_CTRL_TYPE_INTEGER;
> + break;
> + case V4L2_CID_MPEG_VIDEO_FRAME_LTR_INDEX:
> + *type = V4L2_CTRL_TYPE_INTEGER;
> + *flags |= V4L2_CTRL_FLAG_EXECUTE_ON_WRITE;
> + break;
> + case V4L2_CID_MPEG_VIDEO_USE_LTR_FRAMES:
> + *type = V4L2_CTRL_TYPE_BITMASK;
> + *flags |= V4L2_CTRL_FLAG_EXECUTE_ON_WRITE;
> + break;
> case V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME:
> case V4L2_CID_PAN_RESET:
> case V4L2_CID_TILT_RESET:
> diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
> index e37b85f..710bc53 100644
> --- a/include/uapi/linux/v4l2-controls.h
> +++ b/include/uapi/linux/v4l2-controls.h
> @@ -421,6 +421,9 @@ enum v4l2_mpeg_video_multi_slice_mode {
> #define V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE (V4L2_CID_MPEG_BASE+227)
> #define V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE (V4L2_CID_MPEG_BASE+228)
> #define V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME (V4L2_CID_MPEG_BASE+229)
> +#define V4L2_CID_MPEG_VIDEO_LTR_COUNT (V4L2_CID_MPEG_BASE + 230)
> +#define V4L2_CID_MPEG_VIDEO_FRAME_LTR_INDEX (V4L2_CID_MPEG_BASE + 231)
> +#define V4L2_CID_MPEG_VIDEO_USE_LTR_FRAMES (V4L2_CID_MPEG_BASE + 232)
>
> /* CIDs for the MPEG-2 Part 2 (H.262) codec */
> #define V4L2_CID_MPEG_VIDEO_MPEG2_LEVEL (V4L2_CID_MPEG_BASE+270)
>
Note that this and the other patches from you that add V4L2_CID_MPEG_VIDEO controls
will need to be rebased as soon as this PR is merged:
https://patchwork.linuxtv.org/project/linux-media/patch/d68da172-b251-000f-653d-38a8a4c7b715@xxxxxxxxx/
I recommend waiting until that's in.
I currently have the following patches from you adding new controls besides this one:
https://patchwork.linuxtv.org/project/linux-media/patch/1606121442-31074-1-git-send-email-dikshita@xxxxxxxxxxxxxx/
https://patchwork.linuxtv.org/project/linux-media/patch/1605682497-29273-2-git-send-email-dikshita@xxxxxxxxxxxxxx/
https://patchwork.linuxtv.org/project/linux-media/patch/1605682497-29273-3-git-send-email-dikshita@xxxxxxxxxxxxxx/
What is missing is driver support for these new controls. I recommend that, once
the PR mentioned above is merged, you make a new series combining all three
patches + patches that add support for this to the venus driver.
Regards,
Hans