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VP8: eliminate a dereference in coefficient decoding 

Originally committed as revision 24671 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Jason Garrett-Glaser 2010-08-02 22:48:38 +00:00
parent f311208cf1
commit 370b622a45
2 changed files with 19 additions and 12 deletions
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26
libavcodec/vp8.c
View File

@ -195,7 +195,8 @@ typedef struct {
uint8_t golden;
uint8_t pred16x16[4];
uint8_t pred8x8c[3];
uint8_t token[4][8][3][NUM_DCT_TOKENS-1];
/* Padded to allow overreads */
uint8_t token[4][17][3][NUM_DCT_TOKENS-1];
uint8_t mvc[2][19];
} prob[2];
} VP8Context;
@ -388,7 +389,7 @@ static void update_refs(VP8Context *s)
static int decode_frame_header(VP8Context *s, const uint8_t *buf, int buf_size)
{
VP56RangeCoder *c = &s->c;
int header_size, hscale, vscale, i, j, k, l, ret;
int header_size, hscale, vscale, i, j, k, l, m, ret;
int width = s->avctx->width;
int height = s->avctx->height;
@ -428,7 +429,10 @@ static int decode_frame_header(VP8Context *s, const uint8_t *buf, int buf_size)
av_log_missing_feature(s->avctx, "Upscaling", 1);
s->update_golden = s->update_altref = VP56_FRAME_CURRENT;
memcpy(s->prob->token , vp8_token_default_probs , sizeof(s->prob->token));
for (i = 0; i < 4; i++)
for (j = 0; j < 16; j++)
memcpy(s->prob->token[i][j], vp8_token_default_probs[i][vp8_coeff_band[j]],
sizeof(s->prob->token[i][j]));
memcpy(s->prob->pred16x16, vp8_pred16x16_prob_inter, sizeof(s->prob->pred16x16));
memcpy(s->prob->pred8x8c , vp8_pred8x8c_prob_inter , sizeof(s->prob->pred8x8c));
memcpy(s->prob->mvc , vp8_mv_default_prob , sizeof(s->prob->mvc));
@ -488,8 +492,12 @@ static int decode_frame_header(VP8Context *s, const uint8_t *buf, int buf_size)
for (j = 0; j < 8; j++)
for (k = 0; k < 3; k++)
for (l = 0; l < NUM_DCT_TOKENS-1; l++)
if (vp56_rac_get_prob_branchy(c, vp8_token_update_probs[i][j][k][l]))
s->prob->token[i][j][k][l] = vp8_rac_get_uint(c, 8);
if (vp56_rac_get_prob_branchy(c, vp8_token_update_probs[i][j][k][l])) {
int prob = vp8_rac_get_uint(c, 8);
for (m = 0; m < 16; m++)
if (vp8_coeff_band[m] == j)
s->prob->token[i][m][k][l] = prob;
}
if ((s->mbskip_enabled = vp8_rac_get(c)))
s->prob->mbskip = vp8_rac_get_uint(c, 8);
@ -807,7 +815,7 @@ 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 = probs[vp8_coeff_band[i]][zero_nhood];
uint8_t *token_prob = probs[i][zero_nhood];
int nonzero = 0;
int coeff;
@ -819,13 +827,13 @@ 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
token_prob = probs[vp8_coeff_band[i]][0];
token_prob = probs[i][0];
goto skip_eob;
}
if (!vp56_rac_get_prob_branchy(c, token_prob[2])) { // DCT_1
coeff = 1;
token_prob = probs[vp8_coeff_band[i+1]][1];
token_prob = probs[i+1][1];
} else {
if (!vp56_rac_get_prob_branchy(c, token_prob[3])) { // DCT 2,3,4
coeff = vp56_rac_get_prob(c, token_prob[4]);
@ -850,7 +858,7 @@ skip_eob:
coeff += vp8_rac_get_coeff(c, vp8_dct_cat_prob[cat]);
}
}
token_prob = probs[vp8_coeff_band[i+1]][2];
token_prob = probs[i+1][2];
}
// todo: full [16] qmat? load into register?

5
libavcodec/vp8data.h
View File

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