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Trap very short arf group just before a kf.

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Trap the case where we end up with a very short arf group just before
a key frame. Such a group often has poor quality and may cause pulsing.

For example if the KF is 17 frames away we are better doing two mid-size
groups of 9 and 8 than a group of 15 followed by a group of 2.

This becomes more and more important when coding with a short forced
kf interval though it may not impact our standard tests much.

Change-Id: I29d83d6637b203eac69be320dd35a7401a4678c1
This commit is contained in:
paulwilkins
2016-04-07 14:55:26 +01:00
parent 8d8ee1f644
commit 107de19698
1 changed files with 15 additions and 5 deletions
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20
vp9/encoder/vp9_firstpass.c
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@@ -1957,7 +1957,8 @@ static void define_gf_group(VP9_COMP *cpi, FIRSTPASS_STATS *this_frame) {
int int_lbq =
(int)(vp9_convert_qindex_to_q(rc->last_boosted_qindex,
cpi->common.bit_depth));
active_min_gf_interval = rc->min_gf_interval + VPXMIN(2, int_max_q / 200);
active_min_gf_interval =
rc->min_gf_interval + arf_active_or_kf + VPXMIN(2, int_max_q / 200);
if (active_min_gf_interval > rc->max_gf_interval)
active_min_gf_interval = rc->max_gf_interval;
@@ -1968,13 +1969,20 @@ static void define_gf_group(VP9_COMP *cpi, FIRSTPASS_STATS *this_frame) {
// bits to spare and are better with a smaller interval and smaller boost.
// At high Q when there are few bits to spare we are better with a longer
// interval to spread the cost of the GF.
active_max_gf_interval = 12 + VPXMIN(4, (int_lbq / 6));
active_max_gf_interval =
12 + arf_active_or_kf + VPXMIN(4, (int_lbq / 6));
// We have: active_min_gf_interval <= rc->max_gf_interval
if (active_max_gf_interval < active_min_gf_interval)
active_max_gf_interval = active_min_gf_interval;
else if (active_max_gf_interval > rc->max_gf_interval)
active_max_gf_interval = rc->max_gf_interval;
// Would the active max drop us out just before the near the next kf?
if ((active_max_gf_interval <= rc->frames_to_key) &&
(active_max_gf_interval >=
(rc->frames_to_key - rc->min_gf_interval)))
active_max_gf_interval = rc->frames_to_key / 2;
}
}
@@ -2032,11 +2040,13 @@ static void define_gf_group(VP9_COMP *cpi, FIRSTPASS_STATS *this_frame) {
// Break out conditions.
if (
// Break at active_max_gf_interval unless almost totally static.
(i >= (active_max_gf_interval + arf_active_or_kf) &&
zero_motion_accumulator < 0.995) ||
((i >= active_max_gf_interval) &&
(zero_motion_accumulator < 0.995)) ||
(
// Don't break out with a very short interval.
(i >= active_min_gf_interval + arf_active_or_kf) &&
(i >= active_min_gf_interval) &&
// If possible dont break very close to a kf
((rc->frames_to_key - i) >= rc->min_gf_interval) &&
(!flash_detected) &&
((mv_ratio_accumulator > mv_ratio_accumulator_thresh) ||
(abs_mv_in_out_accumulator > 3.0) ||