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Bug fix for second reference stats.

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Immediately following a key frame the trailing second reference
error in the first pass stats will be based on a reference frame from
the prior key frame group and will thus usually be much larger.

This fix eliminates that effect (which typically triggers a short arf
group immediately after a key frame). It also changes the accounting
for the first frame in each new arf group.

This change gives large gains on a couple of clips that contain mid
sequence key frames (e.g. 6% on 1080P tennis). Overall there was
a net gain in PSNR and PSNR-HVS ~(0.05- 0.4%) and mixed results for
SSIM (+/- 0.2%).

Change-Id: I8e00538ac2c0b5c2e7e637903cac329ce5c2a375
This commit is contained in:
paulwilkins 2017-12-04 13:41:44 +00:00
parent 8099220e6c
commit f1ce050f44
1 changed files with 5 additions and 2 deletions
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7
vp9/encoder/vp9_firstpass.c
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@ -2543,8 +2543,11 @@ static void define_gf_group(VP9_COMP *cpi, FIRSTPASS_STATS *this_frame) {
// Update the accumulator for second ref error difference.
// This is intended to give an indication of how much the coded error is
// increasing over time.
sr_accumulator += (next_frame.sr_coded_error - next_frame.coded_error);
sr_accumulator = VPXMAX(0.0, sr_accumulator);
if (i == 1) {
sr_accumulator += next_frame.coded_error;
} else {
sr_accumulator += (next_frame.sr_coded_error - next_frame.coded_error);
}
}
// Break out conditions.