ffmpeg | branch: master | Justin Ruggles <justin.rugg...@gmail.com> | Wed Oct 28 15:38:21 2015 +0100| [a9ba59591ed509fb7e6decfde8da4cbfd4ddf4b8] | committer: Diego Biurrun
ac3dsp: Add some special-case handling for the C downmix function This is about 200% faster for in-decoder downmixing of 5.0 and 5.1 content. Signed-off-by: Diego Biurrun <di...@biurrun.de> > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=a9ba59591ed509fb7e6decfde8da4cbfd4ddf4b8 --- libavcodec/ac3dsp.c | 39 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-) diff --git a/libavcodec/ac3dsp.c b/libavcodec/ac3dsp.c index d1bf37e..8eae5ad 100644 --- a/libavcodec/ac3dsp.c +++ b/libavcodec/ac3dsp.c @@ -174,9 +174,46 @@ static void ac3_extract_exponents_c(uint8_t *exp, int32_t *coef, int nb_coefs) static void ac3_downmix_c(float **samples, float **matrix, int out_ch, int in_ch, int len) { + int **matrix_cmp = (int **)matrix; int i, j; float v0, v1; - if (out_ch == 2) { + + if (in_ch == 5 && out_ch == 2 && + !(matrix_cmp[1][0] | matrix_cmp[0][2] | + matrix_cmp[1][3] | matrix_cmp[0][4] | + (matrix_cmp[0][1] ^ matrix_cmp[1][1]) | + (matrix_cmp[0][0] ^ matrix_cmp[1][2]))) { + float front_mix = matrix[0][0]; + float center_mix = matrix[0][1]; + float surround_mix = matrix[0][3]; + + for (i = 0; i < len; i++) { + v0 = samples[0][i] * front_mix + + samples[1][i] * center_mix + + samples[3][i] * surround_mix; + + v1 = samples[1][i] * center_mix + + samples[2][i] * front_mix + + samples[4][i] * surround_mix; + + samples[0][i] = v0; + samples[1][i] = v1; + } + } else if (in_ch == 5 && out_ch == 1 && + matrix_cmp[0][0] == matrix_cmp[0][2] && + matrix_cmp[0][3] == matrix_cmp[0][4]) { + float front_mix = matrix[0][0]; + float center_mix = matrix[0][1]; + float surround_mix = matrix[0][3]; + + for (i = 0; i < len; i++) { + samples[0][i] = samples[0][i] * front_mix + + samples[1][i] * center_mix + + samples[2][i] * front_mix + + samples[3][i] * surround_mix + + samples[4][i] * surround_mix; + } + } else if (out_ch == 2) { for (i = 0; i < len; i++) { v0 = v1 = 0.0f; for (j = 0; j < in_ch; j++) { _______________________________________________ ffmpeg-cvslog mailing list ffmpeg-cvslog@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-cvslog
