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Mixer: Use a temporary buffer when stretching audio

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This commit is contained in:
MerryMage 2017-04-12 12:56:07 +01:00
parent f5018010d3
commit 9397fdfe95
2 changed files with 24 additions and 27 deletions
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48
Source/Core/AudioCommon/Mixer.cpp
View File

@ -132,20 +132,21 @@ unsigned int CMixer::Mix(short* samples, unsigned int num_samples)
if (SConfig::GetInstance().m_audio_stretch)
{
unsigned int actual_samples = std::min({
m_dma_mixer.AvailableSamples(), m_streaming_mixer.AvailableSamples(), num_samples,
});
unsigned int available_samples =
std::min(m_dma_mixer.AvailableSamples(), m_streaming_mixer.AvailableSamples());
m_dma_mixer.Mix(samples, actual_samples, false);
m_streaming_mixer.Mix(samples, actual_samples, false);
m_wiimote_speaker_mixer.Mix(samples, actual_samples, false);
m_stretch_buffer.fill(0);
m_dma_mixer.Mix(m_stretch_buffer.data(), available_samples, false);
m_streaming_mixer.Mix(m_stretch_buffer.data(), available_samples, false);
m_wiimote_speaker_mixer.Mix(m_stretch_buffer.data(), available_samples, false);
if (!m_is_stretching)
{
m_sound_touch.clear();
m_is_stretching = true;
}
StretchAudio(samples, actual_samples, num_samples);
StretchAudio(m_stretch_buffer.data(), available_samples, samples, num_samples);
}
else
{
@ -158,12 +159,12 @@ unsigned int CMixer::Mix(short* samples, unsigned int num_samples)
return num_samples;
}
void CMixer::StretchAudio(short* samples, unsigned int actual_samples, unsigned int num_samples)
void CMixer::StretchAudio(const short* in, unsigned int num_in, short* out, unsigned int num_out)
{
const double time_delta = static_cast<double>(num_samples) / m_sampleRate; // seconds
const double time_delta = static_cast<double>(num_out) / m_sampleRate; // seconds
// We were given actual_samples number of samples, and num_samples were requested from us.
double current_ratio = static_cast<double>(actual_samples) / static_cast<double>(num_samples);
double current_ratio = static_cast<double>(num_in) / static_cast<double>(num_out);
const double max_latency = SConfig::GetInstance().m_audio_stretch_max_latency;
const double max_backlog = m_sampleRate * max_latency / 1000.0;
@ -171,7 +172,7 @@ void CMixer::StretchAudio(short* samples, unsigned int actual_samples, unsigned
if (backlog_fullness > 1.0)
{
// Exceeded latency budget: Do not add more samples into FIFO.
actual_samples = 0;
num_in = 0;
}
// We ideally want the backlog to be about 50% full.
@ -182,7 +183,7 @@ void CMixer::StretchAudio(short* samples, unsigned int actual_samples, unsigned
// This low-pass filter smoothes out variance in the calculated stretch ratio.
// The time-scale determines how responsive this filter is.
constexpr double lpf_time_scale = 0.3; // seconds
constexpr double lpf_time_scale = 1.0; // seconds
const double m_lpf_gain = 1.0 - std::exp(-time_delta / lpf_time_scale);
m_stretch_ratio += m_lpf_gain * (current_ratio - m_stretch_ratio);
@ -190,29 +191,24 @@ void CMixer::StretchAudio(short* samples, unsigned int actual_samples, unsigned
// many silence samples. These do not need to be timestretched.
m_sound_touch.setTempo(std::max(m_stretch_ratio, 0.1));
if (actual_samples != num_samples)
{
DEBUG_LOG(AUDIO, "Audio stretching: samples:%u/%u ratio:%f backlog:%f gain: %f", actual_samples,
num_samples, m_stretch_ratio, backlog_fullness, m_lpf_gain);
}
DEBUG_LOG(AUDIO, "Audio stretching: samples:%u/%u ratio:%f backlog:%f gain: %f", num_in, num_out,
m_stretch_ratio, backlog_fullness, m_lpf_gain);
m_sound_touch.putSamples(samples, actual_samples);
m_sound_touch.putSamples(in, num_in);
memset(samples, 0, num_samples * 2 * sizeof(short));
const size_t samples_received = m_sound_touch.receiveSamples(samples, num_samples);
const size_t samples_received = m_sound_touch.receiveSamples(out, num_out);
if (samples_received != 0)
{
m_last_stretched_sample[0] = samples[samples_received * 2 - 2];
m_last_stretched_sample[1] = samples[samples_received * 2 - 1];
m_last_stretched_sample[0] = out[samples_received * 2 - 2];
m_last_stretched_sample[1] = out[samples_received * 2 - 1];
}
// Preform padding if we've run out of samples.
for (size_t i = samples_received; i < num_samples; i++)
for (size_t i = samples_received; i < num_out; i++)
{
samples[i * 2 + 0] = m_last_stretched_sample[0];
samples[i * 2 + 1] = m_last_stretched_sample[1];
out[i * 2 + 0] = m_last_stretched_sample[0];
out[i * 2 + 1] = m_last_stretched_sample[1];
}
}

3
Source/Core/AudioCommon/Mixer.h
View File

@ -75,7 +75,7 @@ private:
u32 m_frac = 0;
};
void StretchAudio(short* samples, unsigned int actual_samples, unsigned int num_samples);
void StretchAudio(const short* in, unsigned int num_in, short* out, unsigned int num_out);
MixerFifo m_dma_mixer{this, 32000};
MixerFifo m_streaming_mixer{this, 48000};
@ -86,6 +86,7 @@ private:
soundtouch::SoundTouch m_sound_touch;
double m_stretch_ratio = 1.0;
std::array<short, 2> m_last_stretched_sample = {};
std::array<short, MAX_SAMPLES * 2> m_stretch_buffer;
WaveFileWriter m_wave_writer_dtk;
WaveFileWriter m_wave_writer_dsp;