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Don't allow very short GF groups even when the GF is predicted from an ARF.

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This is basically a slightly modified version of the previous patch,
and it has a moderately positive effect (SSIM/PSNR both +0.08% avg
on derf-set). Most clips show no change, except waterfall/coastguard,
each ~ +0.8% SSIM/PSNR. You can see similar effects in other clips
by shortening their length to terminate at a very short last group
of frames.

Change-Id: I7a70de99ca1f9fe6a8b6ca7a6e30e8a4b64383e4
This commit is contained in:
Ronald S. Bultje 2011-06-02 09:14:51 -07:00
parent 34ba18760f
commit 9f002bee53
1 changed files with 18 additions and 19 deletions
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37
vp8/encoder/firstpass.c
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@ -1553,6 +1553,24 @@ static void define_gf_group(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
cpi->gfu_boost = (int)(boost_score * 100.0) >> 4;
// Dont allow conventional gf too near the next kf
if ((cpi->twopass.frames_to_key - i) < MIN_GF_INTERVAL)
{
while (i < cpi->twopass.frames_to_key)
{
i++;
if (EOF == input_stats(cpi, this_frame))
break;
if (i < cpi->twopass.frames_to_key)
{
mod_frame_err = calculate_modified_err(cpi, this_frame);
gf_group_err += mod_frame_err;
}
}
}
// Should we use the alternate refernce frame
if (allow_alt_ref &&
(i >= MIN_GF_INTERVAL) &&
@ -1675,25 +1693,6 @@ static void define_gf_group(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
cpi->baseline_gf_interval = i;
}
// Conventional GF
if (!cpi->source_alt_ref_pending)
{
// Dont allow conventional gf too near the next kf
if ((cpi->twopass.frames_to_key - cpi->baseline_gf_interval) < MIN_GF_INTERVAL)
{
while (cpi->baseline_gf_interval < cpi->twopass.frames_to_key)
{
if (EOF == input_stats(cpi, this_frame))
break;
cpi->baseline_gf_interval++;
if (cpi->baseline_gf_interval < cpi->twopass.frames_to_key)
gf_group_err += calculate_modified_err(cpi, this_frame);
}
}
}
// Now decide how many bits should be allocated to the GF group as a proportion of those remaining in the kf group.
// The final key frame group in the clip is treated as a special case where cpi->twopass.kf_group_bits is tied to cpi->twopass.bits_left.
// This is also important for short clips where there may only be one key frame.