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Make the quantizer exact.

Browse Source 
This replaces the approximate division-by-multiplication in the
 quantizer with an exact one that costs just one add and one
 shift extra.
The asm versions have not been updated in this patch, and thus
 have been disabled, since the new method requires different
 multipliers which are not compatible with the old method.

Change-Id: I53ac887af0f969d906e464c88b1f4be69c6b1206
This commit is contained in:
Timothy B. Terriberry
2010-06-28 17:15:09 -07:00
parent 08eed049d4
commit e04e293522
7 changed files with 44 additions and 12 deletions
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33
vp8/encoder/encodeframe.c
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@@ -103,6 +103,18 @@ static const int qzbin_factors[129] =
80,
};
static void vp8cx_invert_quant(short *quant, short *shift, short d)
{
unsigned t;
int l;
t = d;
for(l = 0; t > 1; l++)
t>>=1;
t = 1 + (1<<(16+l))/d;
*quant = (short)(t - (1<<16));
*shift = l;
}
void vp8cx_init_quantizer(VP8_COMP *cpi)
{
int r, c;
@@ -116,21 +128,24 @@ void vp8cx_init_quantizer(VP8_COMP *cpi)
{
// dc values
quant_val = vp8_dc_quant(Q, cpi->common.y1dc_delta_q);
cpi->Y1quant[Q][0][0] = (1 << 16) / quant_val;
vp8cx_invert_quant(cpi->Y1quant[Q][0] + 0,
cpi->Y1quant_shift[Q][0] + 0, quant_val);
cpi->Y1zbin[Q][0][0] = ((qzbin_factors[Q] * quant_val) + 64) >> 7;
cpi->Y1round[Q][0][0] = (qrounding_factors[Q] * quant_val) >> 7;
cpi->common.Y1dequant[Q][0][0] = quant_val;
cpi->zrun_zbin_boost_y1[Q][0] = (quant_val * zbin_boost[0]) >> 7;
quant_val = vp8_dc2quant(Q, cpi->common.y2dc_delta_q);
cpi->Y2quant[Q][0][0] = (1 << 16) / quant_val;
vp8cx_invert_quant(cpi->Y2quant[Q][0] + 0,
cpi->Y2quant_shift[Q][0] + 0, quant_val);
cpi->Y2zbin[Q][0][0] = ((qzbin_factors[Q] * quant_val) + 64) >> 7;
cpi->Y2round[Q][0][0] = (qrounding_factors[Q] * quant_val) >> 7;
cpi->common.Y2dequant[Q][0][0] = quant_val;
cpi->zrun_zbin_boost_y2[Q][0] = (quant_val * zbin_boost[0]) >> 7;
quant_val = vp8_dc_uv_quant(Q, cpi->common.uvdc_delta_q);
cpi->UVquant[Q][0][0] = (1 << 16) / quant_val;
vp8cx_invert_quant(cpi->UVquant[Q][0] + 0,
cpi->UVquant_shift[Q][0] + 0, quant_val);
cpi->UVzbin[Q][0][0] = ((qzbin_factors[Q] * quant_val) + 64) >> 7;;
cpi->UVround[Q][0][0] = (qrounding_factors[Q] * quant_val) >> 7;
cpi->common.UVdequant[Q][0][0] = quant_val;
@@ -144,21 +159,24 @@ void vp8cx_init_quantizer(VP8_COMP *cpi)
c = (rc & 3);
quant_val = vp8_ac_yquant(Q);
cpi->Y1quant[Q][r][c] = (1 << 16) / quant_val;
vp8cx_invert_quant(cpi->Y1quant[Q][r] + c,
cpi->Y1quant_shift[Q][r] + c, quant_val);
cpi->Y1zbin[Q][r][c] = ((qzbin_factors[Q] * quant_val) + 64) >> 7;
cpi->Y1round[Q][r][c] = (qrounding_factors[Q] * quant_val) >> 7;
cpi->common.Y1dequant[Q][r][c] = quant_val;
cpi->zrun_zbin_boost_y1[Q][i] = (quant_val * zbin_boost[i]) >> 7;
quant_val = vp8_ac2quant(Q, cpi->common.y2ac_delta_q);
cpi->Y2quant[Q][r][c] = (1 << 16) / quant_val;
vp8cx_invert_quant(cpi->Y2quant[Q][r] + c,
cpi->Y2quant_shift[Q][r] + c, quant_val);
cpi->Y2zbin[Q][r][c] = ((qzbin_factors[Q] * quant_val) + 64) >> 7;
cpi->Y2round[Q][r][c] = (qrounding_factors[Q] * quant_val) >> 7;
cpi->common.Y2dequant[Q][r][c] = quant_val;
cpi->zrun_zbin_boost_y2[Q][i] = (quant_val * zbin_boost[i]) >> 7;
quant_val = vp8_ac_uv_quant(Q, cpi->common.uvac_delta_q);
cpi->UVquant[Q][r][c] = (1 << 16) / quant_val;
vp8cx_invert_quant(cpi->UVquant[Q][r] + c,
cpi->UVquant_shift[Q][r] + c, quant_val);
cpi->UVzbin[Q][r][c] = ((qzbin_factors[Q] * quant_val) + 64) >> 7;
cpi->UVround[Q][r][c] = (qrounding_factors[Q] * quant_val) >> 7;
cpi->common.UVdequant[Q][r][c] = quant_val;
@@ -198,6 +216,7 @@ void vp8cx_mb_init_quantizer(VP8_COMP *cpi, MACROBLOCK *x)
for (i = 0; i < 16; i++)
{
x->block[i].quant = cpi->Y1quant[QIndex];
x->block[i].quant_shift = cpi->Y1quant_shift[QIndex];
x->block[i].zbin = cpi->Y1zbin[QIndex];
x->block[i].round = cpi->Y1round[QIndex];
x->e_mbd.block[i].dequant = cpi->common.Y1dequant[QIndex];
@@ -211,6 +230,7 @@ void vp8cx_mb_init_quantizer(VP8_COMP *cpi, MACROBLOCK *x)
for (i = 16; i < 24; i++)
{
x->block[i].quant = cpi->UVquant[QIndex];
x->block[i].quant_shift = cpi->UVquant_shift[QIndex];
x->block[i].zbin = cpi->UVzbin[QIndex];
x->block[i].round = cpi->UVround[QIndex];
x->e_mbd.block[i].dequant = cpi->common.UVdequant[QIndex];
@@ -221,6 +241,7 @@ void vp8cx_mb_init_quantizer(VP8_COMP *cpi, MACROBLOCK *x)
// Y2
zbin_extra = (cpi->common.Y2dequant[QIndex][0][1] * ((cpi->zbin_over_quant / 2) + cpi->zbin_mode_boost)) >> 7;
x->block[24].quant = cpi->Y2quant[QIndex];
x->block[24].quant_shift = cpi->Y2quant_shift[QIndex];
x->block[24].zbin = cpi->Y2zbin[QIndex];
x->block[24].round = cpi->Y2round[QIndex];
x->e_mbd.block[24].dequant = cpi->common.Y2dequant[QIndex];