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VP8: much faster DC transform handling

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A lot of the time the DC block is empty: don't do the WHT in this case.
A lot of the rest of the time, there's only one coefficient: make a special
DC-only transform for that case.
When the block is empty, don't incorrectly mark luma DCT blocks as having DC
coefficients.

Originally committed as revision 24670 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Jason Garrett-Glaser 2010-08-02 20:57:03 +00:00
parent c934562c12
commit f311208cf1
3 changed files with 29 additions and 8 deletions
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11
libavcodec/vp8.c
View File

@ -868,6 +868,7 @@ void decode_mb_coeffs(VP8Context *s, VP56RangeCoder *c, VP8Macroblock *mb,
int i, x, y, luma_start = 0, luma_ctx = 3;
int nnz_pred, nnz, nnz_total = 0;
int segment = s->segment;
int block_dc = 0;
if (mb->mode != MODE_I4x4 && mb->mode != VP8_MVMODE_SPLIT) {
nnz_pred = t_nnz[8] + l_nnz[8];
@ -876,8 +877,14 @@ void decode_mb_coeffs(VP8Context *s, VP56RangeCoder *c, VP8Macroblock *mb,
nnz = decode_block_coeffs(c, s->block_dc, s->prob->token[1], 0, nnz_pred,
s->qmat[segment].luma_dc_qmul);
l_nnz[8] = t_nnz[8] = !!nnz;
if (nnz) {
nnz_total += nnz;
block_dc = 1;
if (nnz == 1)
s->vp8dsp.vp8_luma_dc_wht_dc(s->block, s->block_dc);
else
s->vp8dsp.vp8_luma_dc_wht(s->block, s->block_dc);
}
luma_start = 1;
luma_ctx = 0;
}
@ -888,8 +895,8 @@ void decode_mb_coeffs(VP8Context *s, VP56RangeCoder *c, VP8Macroblock *mb,
nnz_pred = l_nnz[y] + t_nnz[x];
nnz = decode_block_coeffs(c, s->block[y][x], s->prob->token[luma_ctx], luma_start,
nnz_pred, s->qmat[segment].luma_qmul);
// nnz+luma_start may be one more than the actual last index, but we don't care
s->non_zero_count_cache[y][x] = nnz + luma_start;
// 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;
nnz_total += nnz;
}

21
libavcodec/vp8dsp.c
View File

@ -51,13 +51,25 @@ static void vp8_luma_dc_wht_c(DCTELEM block[4][4][16], DCTELEM dc[16])
dc[i*4+2] = 0;
dc[i*4+3] = 0;
*block[i][0] = (t0 + t1) >> 3;
*block[i][1] = (t3 + t2) >> 3;
*block[i][2] = (t0 - t1) >> 3;
*block[i][3] = (t3 - t2) >> 3;
block[i][0][0] = (t0 + t1) >> 3;
block[i][1][0] = (t3 + t2) >> 3;
block[i][2][0] = (t0 - t1) >> 3;
block[i][3][0] = (t3 - t2) >> 3;
}
}
static void vp8_luma_dc_wht_dc_c(DCTELEM block[4][4][16], DCTELEM dc[16])
{
int i, val = (dc[0] + 3) >> 3;
dc[0] = 0;
for (i = 0; i < 4; i++) {
block[i][0][0] = val;
block[i][1][0] = val;
block[i][2][0] = val;
block[i][3][0] = val;
}
}
#define MUL_20091(a) ((((a)*20091) >> 16) + (a))
#define MUL_35468(a) (((a)*35468) >> 16)
@ -480,6 +492,7 @@ VP8_BILINEAR(4)
av_cold void ff_vp8dsp_init(VP8DSPContext *dsp)
{
dsp->vp8_luma_dc_wht = vp8_luma_dc_wht_c;
dsp->vp8_luma_dc_wht_dc = vp8_luma_dc_wht_dc_c;
dsp->vp8_idct_add = vp8_idct_add_c;
dsp->vp8_idct_dc_add = vp8_idct_dc_add_c;
dsp->vp8_idct_dc_add4y = vp8_idct_dc_add4y_c;

1
libavcodec/vp8dsp.h
View File

@ -31,6 +31,7 @@ typedef void (*vp8_mc_func)(uint8_t *dst/*align 8*/, int dstStride, uint8_t *src
typedef struct VP8DSPContext {
void (*vp8_luma_dc_wht)(DCTELEM block[4][4][16], DCTELEM dc[16]);
void (*vp8_luma_dc_wht_dc)(DCTELEM block[4][4][16], DCTELEM dc[16]);
void (*vp8_idct_add)(uint8_t *dst, DCTELEM block[16], int stride);
void (*vp8_idct_dc_add)(uint8_t *dst, DCTELEM block[16], int stride);
void (*vp8_idct_dc_add4y)(uint8_t *dst, DCTELEM block[4][16], int stride);