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media: allegro: implement scaling of cpb size in SPS 

The cbp_size_value_minus1 in the SPS can scaled using cpb_size_scale to
reduce the number of bits necessary to encode the value. For simplicity,
the scaling was set to 1.

Restructure to the code to make it easier to drop the cbp_size from the
channel and as we are at it, also properly implement the scaling.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
This commit is contained in:
Michael Tretter 2020-12-03 12:00:58 +01:00 committed by Mauro Carvalho Chehab
parent 2e3917e6bd
commit d4a881c1b9
1 changed files with 6 additions and 2 deletions
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8
drivers/media/platform/allegro-dvt/allegro-core.c
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@ -1279,6 +1279,8 @@ static ssize_t allegro_h264_write_sps(struct allegro_channel *channel,
/* Calculation of crop units in Rec. ITU-T H.264 (04/2017) p. 76 */
unsigned int crop_unit_x = 2;
unsigned int crop_unit_y = 2;
unsigned int cpb_size;
unsigned int cpb_size_scale;
sps = kzalloc(sizeof(*sps), GFP_KERNEL);
if (!sps)
@ -1336,13 +1338,15 @@ static ssize_t allegro_h264_write_sps(struct allegro_channel *channel,
sps->vui.vcl_hrd_parameters_present_flag = 1;
sps->vui.vcl_hrd_parameters.cpb_cnt_minus1 = 0;
sps->vui.vcl_hrd_parameters.bit_rate_scale = 0;
sps->vui.vcl_hrd_parameters.cpb_size_scale = 1;
/* See Rec. ITU-T H.264 (04/2017) p. 410 E-53 */
sps->vui.vcl_hrd_parameters.bit_rate_value_minus1[0] =
channel->bitrate_peak / (1 << (6 + sps->vui.vcl_hrd_parameters.bit_rate_scale)) - 1;
/* See Rec. ITU-T H.264 (04/2017) p. 410 E-54 */
cpb_size = channel->cpb_size;
cpb_size_scale = ffs(cpb_size) - 4;
sps->vui.vcl_hrd_parameters.cpb_size_scale = cpb_size_scale;
sps->vui.vcl_hrd_parameters.cpb_size_value_minus1[0] =
(channel->cpb_size * 1000) / (1 << (4 + sps->vui.vcl_hrd_parameters.cpb_size_scale)) - 1;
(cpb_size * 1000) / (1 << (4 + cpb_size_scale)) - 1;
sps->vui.vcl_hrd_parameters.cbr_flag[0] =
!v4l2_ctrl_g_ctrl(channel->mpeg_video_frame_rc_enable);
sps->vui.vcl_hrd_parameters.initial_cpb_removal_delay_length_minus1 = 31;