void AudioBuffer::convert(const AudioSpec &_new_spec)
{
	if(_new_spec == m_spec) {
		return;
	}

	AudioSpec new_spec = _new_spec;
	AudioBuffer dest[2];
	unsigned bufidx = 0;
	AudioBuffer *source = this;

	if(source->rate() != new_spec.rate) {
#if HAVE_LIBSAMPLERATE
		if(source->format() != AUDIO_FORMAT_F32) {
			dest[1].set_spec({AUDIO_FORMAT_F32, source->channels(), source->rate()});
			source->convert_format(dest[1], source->frames());
			source = &dest[1];
		}
		dest[0].set_spec({source->format(), source->channels(), new_spec.rate});
		source->convert_rate(dest[0], source->frames(), nullptr);
		source = &dest[0];
		bufidx = 1;
#else
		new_spec.rate = source->rate();
#endif
	}
	if(source->channels() != new_spec.channels) {
		dest[bufidx].set_spec({source->format(),new_spec.channels,source->rate()});
		source->convert_channels(dest[bufidx], source->frames());
		source = &dest[bufidx];
		bufidx = (bufidx + 1) % 2;
	}
	if(source->format() != new_spec.format) {
		dest[bufidx].set_spec({new_spec.format,source->channels(),source->rate()});
		source->convert_format(dest[bufidx], source->frames());
		source = &dest[bufidx];
	}

	if(new_spec != m_spec) {
		m_data = source->m_data;
		m_spec = new_spec;
	}
}
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
}