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VP8: simplify decode_block_coeffs to avoid having to track nonzero coeffs

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Slightly faster.

Originally committed as revision 24689 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Jason Garrett-Glaser 2010-08-04 01:38:08 +00:00
parent d0c38ea0aa
commit afb54a85c3
1 changed files with 10 additions and 10 deletions
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20
libavcodec/vp8.c
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@ -826,17 +826,20 @@ static int decode_block_coeffs(VP56RangeCoder *c, DCTELEM block[16],
int i, int zero_nhood, int16_t qmul[2])
{
uint8_t *token_prob = probs[i][zero_nhood];
int nonzero = 0;
int coeff;
if (!vp56_rac_get_prob_branchy(c, token_prob[0]))
return 0;
goto skip_eob;
do {
if (!vp56_rac_get_prob_branchy(c, token_prob[0])) // DCT_EOB
return nonzero;
return i;
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
return i; // invalid input; blocks should end with EOB
token_prob = probs[i][0];
goto skip_eob;
}
@ -870,13 +873,10 @@ skip_eob:
}
token_prob = probs[i+1][2];
}
// todo: full [16] qmat? load into register?
block[zigzag_scan[i]] = (vp8_rac_get(c) ? -coeff : coeff) * qmul[!!i];
nonzero = ++i;
} while (i < 16);
} while (++i < 16);
return nonzero;
return i;
}
static av_always_inline
@ -910,9 +910,9 @@ void decode_mb_coeffs(VP8Context *s, VP56RangeCoder *c, VP8Macroblock *mb,
// luma blocks
for (y = 0; y < 4; y++)
for (x = 0; x < 4; x++) {
nnz_pred = l_nnz[y] + t_nnz[x];
nnz_pred = l_nnz[y] + t_nnz[x];START_TIMER;
nnz = decode_block_coeffs(c, s->block[y][x], s->prob->token[luma_ctx], luma_start,
nnz_pred, s->qmat[segment].luma_qmul);
nnz_pred, s->qmat[segment].luma_qmul);STOP_TIMER("test");
// nnz+block_dc may be one more than the actual last index, but we don't care
s->non_zero_count_cache[y][x] = nnz + block_dc;
t_nnz[x] = l_nnz[y] = !!nnz;