void AudioBuffer::convert_rate(AudioBuffer &_dest, unsigned _frames_count, SRC_STATE *_SRC)
{
AudioSpec destspec{AUDIO_FORMAT_F32, m_spec.channels, _dest.rate()};
if(m_spec.format != AUDIO_FORMAT_F32 || _dest.spec() != destspec) {
throw std::logic_error("unsupported format");
}
_frames_count = std::min(frames(),_frames_count);
double rate_ratio = double(destspec.rate)/double(m_spec.rate);
unsigned out_frames = unsigned(ceil(double(_frames_count) * rate_ratio));
if(out_frames==0) {
return;
}
unsigned destpos = _dest.samples();
unsigned destframes = _dest.frames();
_dest.resize_frames(_dest.frames()+out_frames);
#if HAVE_LIBSAMPLERATE
SRC_DATA srcdata;
srcdata.data_in = &at<float>(0);
srcdata.data_out = &_dest.at<float>(destpos);
srcdata.input_frames = _frames_count;
srcdata.output_frames = out_frames;
srcdata.src_ratio = rate_ratio;
int srcresult;
if(_SRC != nullptr) {
srcdata.end_of_input = 0;
srcresult = src_process(_SRC, &srcdata);
} else {
srcdata.end_of_input = 1;
srcresult = src_simple(&srcdata, SRC_SINC_BEST_QUALITY, destspec.channels) ;
}
if(srcresult != 0) {
throw std::runtime_error(std::string("error resampling: ") + src_strerror(srcresult));
}
assert(srcdata.output_frames_gen>=0 && srcdata.output_frames_gen<=out_frames);
if(srcdata.output_frames_gen != out_frames) {
_dest.resize_frames(destframes + srcdata.output_frames_gen);
}
PDEBUGF(LOG_V2, LOG_MIXER, "convert rate: f-in: %d, f-out: %d, gen: %d\n",
_frames_count, out_frames, srcdata.output_frames_gen);
#else
for(unsigned i=destpos; i<_dest.samples(); ++i) {
_dest.operator[]<float>(i) = 0.f;
}
#endif
}
void AudioBuffer::convert_channels(const AudioBuffer &_source, AudioBuffer &_dest,
unsigned _frames_count)
{
unsigned d = _dest.samples();
_dest.resize_frames(_dest.frames()+_frames_count);
if(_source.channels()==1 && _dest.channels()==2) {
//from mono to stereo
for(unsigned i=0; i<_frames_count; ++i) {
T ch1 = _source.at<T>(i);
_dest.operator[]<T>(d+i*2) = ch1;
_dest.operator[]<T>(d+i*2+1) = ch1;
}
} else if(_source.channels()==2 && _dest.channels()==1) {
//from stereo to mono
for(unsigned i=0; i<_frames_count; ++i) {
double ch1 = double(_source.at<T>(i*2));
double ch2 = double(_source.at<T>(i*2+1));
_dest.operator[]<T>(d+i) = T((ch1 + ch2) / 2.0);
}
}
}