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Bug 979705 - Re-write the upmixing functions in the WASAPI cubeb backend to fix mono audio and surround compatibility. r=padenot

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This commit is contained in:
Paul17041993 2015-04-20 15:58:27 +02:00
parent c76f9a219d
commit ad02172e18
1 changed files with 25 additions and 17 deletions
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42
media/libcubeb/src/cubeb_wasapi.cpp
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@ -392,14 +392,12 @@ float stream_to_mix_samplerate_ratio(cubeb_stream * stream)
return float(stream->stream_params.rate) / stream->mix_params.rate;
}
/* Upmix function, copies a mono channel in two interleaved
* stereo channel. |out| has to be twice as long as |in| */
/* Upmix function, copies a mono channel into L and R */
template<typename T>
void
mono_to_stereo(T * in, long insamples, T * out)
mono_to_stereo(T * in, long insamples, T * out, int32_t out_channels)
{
int j = 0;
for (int i = 0; i < insamples; ++i, j += 2) {
for (int i = 0, j = 0; i < insamples; ++i, j += out_channels) {
out[j] = out[j + 1] = in[i];
}
}
@ -408,22 +406,32 @@ template<typename T>
void
upmix(T * in, long inframes, T * out, int32_t in_channels, int32_t out_channels)
{
XASSERT(out_channels >= in_channels);
XASSERT(out_channels >= in_channels && in_channels > 0);
/* Either way, if we have 2 or more channels, the first two are L and R. */
/* If we are playing a mono stream over stereo speakers, copy the data over. */
if (in_channels == 1 && out_channels == 2) {
mono_to_stereo(in, inframes, out);
if (in_channels == 1 && out_channels >= 2) {
mono_to_stereo(in, inframes, out, out_channels);
} else {
/* Copy through. */
for (int i = 0, o = 0; i < inframes * in_channels'
i += in_channels, o += out_channels) {
for (int j = 0; j < in_channels; ++j) {
out[o + j] = in[i + j];
}
}
}
/* Check if more channels. */
if (out_channels <= 2) {
return;
}
/* Otherwise, put silence in other channels. */
long out_index = 0;
for (long i = 0; i < inframes * in_channels; i += in_channels) {
for (int j = 0; j < in_channels; ++j) {
out[out_index + j] = in[i + j];
/* Put silence in remaining channels. */
for (long i = 0, o = 0; i < inframes; ++i, o += out_channels) {
for (int j = 2; j < out_channels; ++j) {
out[o + j] = 0.0;
}
for (int j = in_channels; j < out_channels; ++j) {
out[out_index + j] = 0.0;
}
out_index += out_channels;
}
}