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add 5.1 to stereo downmix to resample.c

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this is based on previous 6to2channel-resample.patch from ffmpeg2theora
but updated to work with trunk and using av_clip_int16.
This commit is contained in:
jan gerber 2011-05-23 17:22:02 +02:00 committed by Michael Niedermayer
parent 01a73d6cef
commit 02260ccc3b
1 changed files with 39 additions and 1 deletions
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40
libavcodec/resample.c
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@ -108,6 +108,39 @@ static void mono_to_stereo(short *output, short *input, int n1)
} }
} }
/*
5.1 to stereo input: [fl, fr, c, lfe, rl, rr]
- Left = front_left + rear_gain * rear_left + center_gain * center
- Right = front_right + rear_gain * rear_right + center_gain * center
Where rear_gain is usually around 0.5-1.0 and
center_gain is almost always 0.7 (-3 dB)
*/
static void surround_to_stereo(short **output, short *input, int channels, int samples)
{
int i;
short l, r;
for (i = 0; i < samples; i++) {
int fl,fr,c,rl,rr,lfe;
fl = input[0];
fr = input[1];
c = input[2];
lfe = input[3];
rl = input[4];
rr = input[5];
l = av_clip_int16(fl + (0.5 * rl) + (0.7 * c));
r = av_clip_int16(fr + (0.5 * rr) + (0.7 * c));
/* output l & r. */
*output[0]++ = l;
*output[1]++ = r;
/* increment input. */
input += channels;
}
}
static void deinterleave(short **output, short *input, int channels, int samples) static void deinterleave(short **output, short *input, int channels, int samples)
{ {
int i, j; int i, j;
@ -301,6 +334,10 @@ int audio_resample(ReSampleContext *s, short *output, short *input, int nb_sampl
} else if (s->output_channels >= 2 && s->input_channels == 1) { } else if (s->output_channels >= 2 && s->input_channels == 1) {
buftmp3[0] = bufout[0]; buftmp3[0] = bufout[0];
memcpy(buftmp2[0], input, nb_samples * sizeof(short)); memcpy(buftmp2[0], input, nb_samples * sizeof(short));
} else if (s->input_channels == 6 && s->output_channels ==2) {
buftmp3[0] = bufout[0];
buftmp3[1] = bufout[1];
surround_to_stereo(buftmp2, input, s->input_channels, nb_samples);
} else if (s->output_channels >= s->input_channels && s->input_channels >= 2) { } else if (s->output_channels >= s->input_channels && s->input_channels >= 2) {
for (i = 0; i < s->input_channels; i++) { for (i = 0; i < s->input_channels; i++) {
buftmp3[i] = bufout[i]; buftmp3[i] = bufout[i];
@ -330,7 +367,8 @@ int audio_resample(ReSampleContext *s, short *output, short *input, int nb_sampl
mono_to_stereo(output, buftmp3[0], nb_samples1); mono_to_stereo(output, buftmp3[0], nb_samples1);
} else if (s->output_channels == 6 && s->input_channels == 2) { } else if (s->output_channels == 6 && s->input_channels == 2) {
ac3_5p1_mux(output, buftmp3[0], buftmp3[1], nb_samples1); ac3_5p1_mux(output, buftmp3[0], buftmp3[1], nb_samples1);
} else if (s->output_channels == s->input_channels && s->input_channels >= 2) { } else if ((s->output_channels == s->input_channels && s->input_channels >= 2) ||
(s->output_channels == 2 && s->input_channels == 6)) {
interleave(output, buftmp3, s->output_channels, nb_samples1); interleave(output, buftmp3, s->output_channels, nb_samples1);
} }