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change the threshold of DC check for encode breakout

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Previously, the DC check is to make sure there is no code-able
DC shift for quantizer Q0, which has been verified rather
conservative. This commit changes the criteria to have two
components, DC and AC, to address the conservativeness. First,
it checks if all AC energy is enough to contribute a single
non-zero quantized AC coefficient. Second, for DC, the decision
to skip further considers two possible scenarios: 1. There is
no code-able 2nd order DC coefficient at all; 2 The residue is
relatively flat, but the uniform DC change is very small, i.e.
less than 1/2 gray level per pixel.

Comparing to previous criteria, the new criteria is about 10%
to 15% faster in encoding time with a very small quality loss.
(threshold ~1000 and quality range 33db-45db)

It should be noted that this commit enables "automatic" static
threshold for encodebreakout if a non-zero small value is passed
in to encoder.

Change-Id: I0f77719a1ac2c2dfddbd950d84920df374515ce3
This commit is contained in:
Yaowu Xu 2011-01-19 16:21:01 -08:00
parent 82266a1ac9
commit 8f279596cb
1 changed files with 12 additions and 5 deletions
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17
vp8/encoder/rdopt.c
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@ -2267,22 +2267,28 @@ int vp8_rd_pick_inter_mode(VP8_COMP *cpi, MACROBLOCK *x, int recon_yoffset, int
else if (x->encode_breakout)
{
int sum, sse;
int threshold = (xd->block[0].dequant[1]
* xd->block[0].dequant[1] >>4);
if(threshold < x->encode_breakout)
threshold = x->encode_breakout;
VARIANCE_INVOKE(&cpi->rtcd.variance, get16x16var)
(x->src.y_buffer, x->src.y_stride,
x->e_mbd.predictor, 16, (unsigned int *)(&sse), &sum);
if (sse < x->encode_breakout)
if (sse < threshold)
{
// Check u and v to make sure skip is ok
int sse2 = 0;
// add dc check
if (abs(sum) < (cpi->common.Y2dequant[0][0] << 2))
/* If theres is no codeable 2nd order dc
or a very small uniform pixel change change */
if (abs(sum) < (xd->block[24].dequant[0]<<2)||
((sum * sum>>8) > sse && abs(sum) <128))
{
sse2 = VP8_UVSSE(x, IF_RTCD(&cpi->rtcd.variance));
if (sse2 * 2 < x->encode_breakout)
if (sse2 * 2 < threshold)
{
x->skip = 1;
distortion2 = sse + sse2;
@ -2428,6 +2434,7 @@ int vp8_rd_pick_inter_mode(VP8_COMP *cpi, MACROBLOCK *x, int recon_yoffset, int
if (x->skip)
break;
}
// Reduce the activation RD thresholds for the best choice mode