From: Philipp Zabel Date: Wed, 28 Nov 2018 13:01:21 +0000 (-0500) Subject: media: v4l2: clarify H.264 loop filter offset controls X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=d338e17993f78155196af4cb780d8271996a02ac;p=linux.git media: v4l2: clarify H.264 loop filter offset controls The venus and s5p-mfc drivers add the loop filter alpha/beta offset controls V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_ALPHA/BETA with a range of -6 to +6, inclusive. This is exactly the range specified for the slice header fields slice_alpha_c0_offset_div2 and slice_beta_offset_div2, which store half the actual filter offsets FilterOffsetA/B. Clarify that this control contains the halved offsets. Signed-off-by: Philipp Zabel Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- diff --git a/Documentation/media/uapi/v4l/extended-controls.rst b/Documentation/media/uapi/v4l/extended-controls.rst index 4e6255dd11a56..0b302413ab3a4 100644 --- a/Documentation/media/uapi/v4l/extended-controls.rst +++ b/Documentation/media/uapi/v4l/extended-controls.rst @@ -1117,10 +1117,16 @@ enum v4l2_mpeg_video_h264_loop_filter_mode - ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_ALPHA (integer)`` Loop filter alpha coefficient, defined in the H264 standard. + This value corresponds to the slice_alpha_c0_offset_div2 slice header + field, and should be in the range of -6 to +6, inclusive. The actual alpha + offset FilterOffsetA is twice this value. Applicable to the H264 encoder. ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_BETA (integer)`` Loop filter beta coefficient, defined in the H264 standard. + This corresponds to the slice_beta_offset_div2 slice header field, and + should be in the range of -6 to +6, inclusive. The actual beta offset + FilterOffsetB is twice this value. Applicable to the H264 encoder. .. _v4l2-mpeg-video-h264-entropy-mode: