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AAC: Unroll code within decode_spectrum_and_dequant(). Gives 12% net speed gain. 

Patch by Alex Converse (alex converse gmail com)

Originally committed as revision 16040 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Alex Converse 2008-12-09 17:08:40 +00:00 committed by Robert Swain
parent 8821210575
commit c0893c3abb
1 changed files with 26 additions and 9 deletions
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35
libavcodec/aac.c
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@ -784,12 +784,19 @@ static int decode_spectrum_and_dequant(AACContext * ac, float coef[1024], GetBit
}
vq_ptr = &ff_aac_codebook_vectors[cur_band_type - 1][index * dim];
if (is_cb_unsigned) {
for (j = 0; j < dim; j++)
if (vq_ptr[j])
coef[coef_tmp_idx + j] = 1 - 2*(int)get_bits1(gb);
if (vq_ptr[0]) coef[coef_tmp_idx ] = 1 - 2*(int)get_bits1(gb);
if (vq_ptr[1]) coef[coef_tmp_idx + 1] = 1 - 2*(int)get_bits1(gb);
if (dim == 4) {
if (vq_ptr[2]) coef[coef_tmp_idx + 2] = 1 - 2*(int)get_bits1(gb);
if (vq_ptr[3]) coef[coef_tmp_idx + 3] = 1 - 2*(int)get_bits1(gb);
}
}else {
for (j = 0; j < dim; j++)
coef[coef_tmp_idx + j] = 1.0f;
coef[coef_tmp_idx ] = 1.0f;
coef[coef_tmp_idx + 1] = 1.0f;
if (dim == 4) {
coef[coef_tmp_idx + 2] = 1.0f;
coef[coef_tmp_idx + 3] = 1.0f;
}
}
if (cur_band_type == ESC_BT) {
for (j = 0; j < 2; j++) {
@ -808,10 +815,20 @@ static int decode_spectrum_and_dequant(AACContext * ac, float coef[1024], GetBit
coef[coef_tmp_idx + j] *= vq_ptr[j];
}
}else
for (j = 0; j < dim; j++)
coef[coef_tmp_idx + j] *= vq_ptr[j];
for (j = 0; j < dim; j++)
coef[coef_tmp_idx + j] *= sf[idx];
{
coef[coef_tmp_idx ] *= vq_ptr[0];
coef[coef_tmp_idx + 1] *= vq_ptr[1];
if (dim == 4) {
coef[coef_tmp_idx + 2] *= vq_ptr[2];
coef[coef_tmp_idx + 3] *= vq_ptr[3];
}
}
coef[coef_tmp_idx ] *= sf[idx];
coef[coef_tmp_idx + 1] *= sf[idx];
if (dim == 4) {
coef[coef_tmp_idx + 2] *= sf[idx];
coef[coef_tmp_idx + 3] *= sf[idx];
}
}
}
}