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| author | Philipp Zabel <p.zabel@pengutronix.de> | 2018-11-28 16:01:21 +0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2018-12-07 16:17:21 +0300 |
| commit | d338e17993f78155196af4cb780d8271996a02ac (patch) | |
| tree | c6ef2186898b3802fc3afe5483eb862dc1391305 /Documentation/media | |
| parent | 91dc5e91edf767e27db4ee1fae19b56cd21152c0 (diff) | |
| download | linux-d338e17993f78155196af4cb780d8271996a02ac.tar.xz | |
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 <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Diffstat (limited to 'Documentation/media')
| -rw-r--r-- | Documentation/media/uapi/v4l/extended-controls.rst | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/media/uapi/v4l/extended-controls.rst b/Documentation/media/uapi/v4l/extended-controls.rst index 4e6255dd11a5..0b302413ab3a 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: |