media: v4l2: clarify H.264 loop filter offset controls (d338e179) · Commits · 戴 / test

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>

Documentation/media/uapi/v4l/extended-controls.rst

+6 −0

Original line number	Diff line number	Diff line
		@@ -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:

Admin message