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VP8: simplify token_prob handling

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~1.5% faster decode_block_coeffs

Originally committed as revision 24659 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Jason Garrett-Glaser 2010-08-02 05:20:38 +00:00
parent 9c87c03779
commit 10bf2eebbe
2 changed files with 6 additions and 9 deletions
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10
libavcodec/vp8.c
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@ -810,13 +810,11 @@ static int decode_block_coeffs(VP56RangeCoder *c, DCTELEM block[16],
uint8_t probs[8][3][NUM_DCT_TOKENS-1],
int i, int zero_nhood, int16_t qmul[2])
{
uint8_t *token_prob;
uint8_t *token_prob = probs[vp8_coeff_band[i]][zero_nhood];
int nonzero = 0;
int coeff;
do {
token_prob = probs[vp8_coeff_band[i]][zero_nhood];
if (!vp56_rac_get_prob_branchy(c, token_prob[0])) // DCT_EOB
return nonzero;
@ -824,17 +822,14 @@ skip_eob:
if (!vp56_rac_get_prob_branchy(c, token_prob[1])) { // DCT_0
if (++i == 16)
return nonzero; // invalid input; blocks should end with EOB
zero_nhood = 0;
token_prob = probs[vp8_coeff_band[i]][0];
goto skip_eob;
}
if (!vp56_rac_get_prob_branchy(c, token_prob[2])) { // DCT_1
coeff = 1;
zero_nhood = 1;
token_prob = probs[vp8_coeff_band[i+1]][1];
} else {
zero_nhood = 2;
if (!vp56_rac_get_prob_branchy(c, token_prob[3])) { // DCT 2,3,4
coeff = vp56_rac_get_prob(c, token_prob[4]);
if (coeff)
@ -858,6 +853,7 @@ skip_eob:
coeff += vp8_rac_get_coeff(c, vp8_dct_cat_prob[cat]);
}
}
token_prob = probs[vp8_coeff_band[i+1]][2];
}
// todo: full [16] qmat? load into register?

5
libavcodec/vp8data.h
View File

@ -314,9 +314,10 @@ static const int8_t vp8_segmentid_tree[][2] =
{ -2, -3 }, // '10', '11'
};
static const uint8_t vp8_coeff_band[16] =
/* Padded by one byte to allow overreads */
static const uint8_t vp8_coeff_band[17] =
{
0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7
0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7, 0
};
static const uint8_t vp8_dct_cat1_prob[] = { 159, 0 };