Messages in this thread | | | Date | Thu, 27 Aug 2020 12:29:09 +0530 | From | dikshita@codeauro ... | Subject | Re: [PATCH v2] media: v4l2-ctrl: add control for long term reference. |
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Hi Hans,
Thanks for your comments.
On 2020-08-25 15:34, Hans Verkuil wrote: > On 14/08/2020 07:29, Dikshita Agarwal wrote: >> LTR (Long Term Reference) 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@codeaurora.org> >> --- >> .../userspace-api/media/v4l/ext-ctrls-codec.rst | 23 >> ++++++++++++++++++++++ >> drivers/media/v4l2-core/v4l2-ctrls.c | 6 ++++++ >> include/uapi/linux/v4l2-controls.h | 4 ++++ >> 3 files changed, 33 insertions(+) >> >> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst >> b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst >> index d0d506a..6d1b005 100644 >> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst >> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst >> @@ -4272,3 +4272,26 @@ 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_LTRCOUNT (enum)`` > > I prefer _LTR_COUNT (same for the other control defines). > > I assume 'enum' is a mistake? This should be 'integer', right? Right, I will correct it at all the places. > >> + Specifies the number of Long Term Reference frames encoder needs to >> + generate or keep. >> + This control is used to query or configure the number of Long Term >> + Reference frames. > > Add something like: "Applicable to the H264 and HEVC encoder." Sure. > >> + >> +``V4L2_CID_MPEG_VIDEO_MARKLTRFRAME (enum)`` >> + This control is used to mark current frame as Long Term Reference >> + frame. > > enum -> integer > _MARK_LTR_FRAME > > How about renaming this to: "_FRAME_LTR_INDEX"? You are suggesting to rename it to V4L2_CID_MPEG_VIDEO_MARK_LTR_FRAME or V4L2_CID_MPEG_VIDEO_MARK_FRAME_LTR_INDEX ? > > I would also suggest having the range as 0..LTR_COUNT where 0 means > that > this is not a LTR frame. An alternative is to have two controls: one > boolean > that determines if the frame is a LTR frame or not, and one control > containing > the LTR index. > > Is the LTR index 0 or 1 based according to the standard? I think that > if it is > 1 based you can use 0 to mean 'not an LTR frame'. If it is 0 based in > the standard, > then having two controls might be better. > > A third alternative might be to use -1 as the value to indicate that it > is not > an LTR frame, but it feels hackish. I'm not sure yet. > Could you please help me to understand how this info will be helpful? This control won't be set by client for every frame. So a frame for which this control is not set is not a LTR frame and a frame for which this control is set is a LTR frame and will be marked with LTR index ranging from 0 to LTR_COUNT-1 (range is according to standard) >> + this provides a Long Term Reference index that ranges from 0 >> + to LTR count-1 and then the particular frame will be marked with >> that >> + Long Term Reference index. > > Add something like: "Applicable to the H264 and HEVC encoder." sure, will add. > > This only makes sense when used with requests, right? Otherwise you > cannot > reliably associate this control with a frame. That should be mentioned > here. Sure, will add. > >> + >> +``V4L2_CID_MPEG_VIDEO_USELTRFRAME (enum)`` > > enum -> bitmask > _USE_LTR_FRAMES Will correct this in next patch. > >> + Specifies the Long Term Reference frame(s) to be used for encoding >> + the current frame. >> + This provides a bitmask which consists of bits [0, 15]. A total of N >> + LSB bits of this field are valid, where N is the maximum number of >> + Long Term Reference frames supported. >> + All the other bits are invalid and should be rejected. >> + The LSB corresponds to the Long Term Reference index 0. Bit N-1 from >> + the LSB corresponds to the Long Term Reference index max LTR >> count-1. > > Add something like: "Applicable to the H264 and HEVC encoder." > > This too only makes sense when using requests, correct? That should be > mentioned > here. Sure, will do. > > I assume that this must be set to 0 for LTR frames? Or at least this > control will > be ignored for LTR frames. Yes, frames marked as LTR frames will not be encoded by using any other LTR frame as a reference. So this control won't be set for LTR frames. This will be set only for the frames which needs to be encoded by using an LTR frame as a reference. > >> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c >> b/drivers/media/v4l2-core/v4l2-ctrls.c >> index 3f3fbcd..3138c72 100644 >> --- a/drivers/media/v4l2-core/v4l2-ctrls.c >> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c >> @@ -991,6 +991,9 @@ const char *v4l2_ctrl_get_name(u32 id) >> case V4L2_CID_MPEG_VIDEO_HEVC_SLICE_PARAMS: return "HEVC Slice >> Parameters"; >> case V4L2_CID_MPEG_VIDEO_HEVC_DECODE_MODE: return "HEVC Decode >> Mode"; >> case V4L2_CID_MPEG_VIDEO_HEVC_START_CODE: return "HEVC Start Code"; >> + case V4L2_CID_MPEG_VIDEO_LTRCOUNT: return "LTR Count"; >> + case V4L2_CID_MPEG_VIDEO_MARKLTRFRAME: return "Mark LTR"; >> + case V4L2_CID_MPEG_VIDEO_USELTRFRAME: return "Use LTR"; > > "Use LTR Frames" > >> >> /* CAMERA controls */ >> /* Keep the order of the 'case's the same as in v4l2-controls.h! */ >> @@ -1224,6 +1227,9 @@ void v4l2_ctrl_fill(u32 id, const char **name, >> enum v4l2_ctrl_type *type, >> break; >> case V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE: >> case V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE: >> + case V4L2_CID_MPEG_VIDEO_LTRCOUNT: >> + case V4L2_CID_MPEG_VIDEO_MARKLTRFRAME: >> + case V4L2_CID_MPEG_VIDEO_USELTRFRAME: >> *type = V4L2_CTRL_TYPE_INTEGER; >> break; >> case V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME: >> diff --git a/include/uapi/linux/v4l2-controls.h >> b/include/uapi/linux/v4l2-controls.h >> index 6227141..f2daa86 100644 >> --- a/include/uapi/linux/v4l2-controls.h >> +++ b/include/uapi/linux/v4l2-controls.h >> @@ -742,6 +742,10 @@ enum >> v4l2_cid_mpeg_video_hevc_size_of_length_field { >> #define >> V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L6_BR (V4L2_CID_MPEG_BASE + 642) >> #define >> V4L2_CID_MPEG_VIDEO_REF_NUMBER_FOR_PFRAMES (V4L2_CID_MPEG_BASE + 643) >> #define V4L2_CID_MPEG_VIDEO_PREPEND_SPSPPS_TO_IDR (V4L2_CID_MPEG_BASE >> + 644) >> +#define V4L2_CID_MPEG_VIDEO_LTRCOUNT (V4L2_CID_MPEG_BASE + 645) >> +#define V4L2_CID_MPEG_VIDEO_MARKLTRFRAME (V4L2_CID_MPEG_BASE + 646) >> +#define V4L2_CID_MPEG_VIDEO_USELTRFRAME (V4L2_CID_MPEG_BASE + 647) >> + >> >> /* MPEG-class control IDs specific to the CX2341x driver as defined >> by V4L2 */ >> #define V4L2_CID_MPEG_CX2341X_BASE (V4L2_CTRL_CLASS_MPEG | 0x1000) >> > > Regards, > > Hans
Thanks, Dikshita
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