Hey all,<div><br></div><div>I&#39;m looking for an open-source time-stretching library, suitable for RT work.</div><div>I&#39;ve googled and come up with the following list, which I can&#39;t choose from:</div><div><br></div>
<div>-Soundtouch : <a href="http://www.surina.net/soundtouch/index.html">http://www.surina.net/soundtouch/index.html</a></div><div>-ClearScale / DspDimension: <a href="http://www.clearscale.org/">http://www.clearscale.org/</a></div>
<div>-SecretRabbitCode / libsamplerate : <a href="http://www.mega-nerd.com/SRC/">http://www.mega-nerd.com/SRC/</a></div><div>-LibResample : <a href="https://ccrma.stanford.edu/~jos/resample/">https://ccrma.stanford.edu/~jos/resample/</a></div>
<div>-MFFM timescale: <a href="http://mffmtimescale.sourceforge.net/">http://mffmtimescale.sourceforge.net/</a></div><div>-LibZita-Resampler: <a href="http://www.kokkinizita.net/linuxaudio/zita-resampler/resampler.html">http://www.kokkinizita.net/linuxaudio/zita-resampler/resampler.html</a></div>
<div><br></div><div>I&#39;m attepmting to write a sample player, that will time-stretch long loops to stay in sync</div><div>with JACK transport.</div><div><br></div><div>I&#39;ve deduced this is what I need to do:</div><div>
- Calculate the amount of samples I need to change the buffer length by</div><div>- Take the buffer, resample it to a larger / smaller amount of samples.</div><div>- Playback the samples as I normally would, except that there&#39;s more, and hence the audio will stay in sync.</div>
<div><br></div><div>Design choices:</div><div>1. should I re-sample the whole buffer, and then playback from that buffer?</div><div>this approach might cause a lot of CPU strain once the rate changes, as the *whole* buffer would</div>
<div>be re-sampled at the same time. Once done, the CPU has no strain from resampling.</div><div><br></div><div>2. Resample &quot;nframes&quot; amount of samples from the buffer, and play them back?</div><div>Less sudden CPU overhead, more constant CPU usage. </div>
<div><br></div><div>The other problem I&#39;m faced with is that some libraries mention that they do *not* support &quot;<span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; ">dynamically variable resampling ratios&quot;.</span></div>
<div><font class="Apple-style-span" face="arial, helvetica, sans-serif">Would I need this? I think I do, as to get the beat &quot;on-time&quot; sometimes I&#39;d need to add 200 samples, while in other cases 210 samples</font></div>
<div><font class="Apple-style-span" face="arial, helvetica, sans-serif">might suit better... </font></div><div><br></div><div>I&#39;m aware that Ardour uses SoundTouch, but I&#39;m not sure is that the best lib for real-time use.</div>
<div>Mixxx is using LibSamplerate AFAIK, and does so quite well, but might not be as suitable as Soundtouch..</div><div><br></div><div><a href="http://www.surina.net/soundtouch/faq.html#sample_processing">http://www.surina.net/soundtouch/faq.html#sample_processing</a></div>
<div>These kind of paragraphs are what stop me from just choosing one and going with it...</div><div><br></div><div>Choices, Advice, Laughter, Help, etc all welcome! :-)</div><div>Cheers, -Harry</div>