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<p lang="en-US" style="margin-bottom: 0in">May be this helps.</p>
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<p lang="en-US" style="margin-bottom: 0in">Pd's block size in preferences controls the actual ASIO buffer for the sound card.</p>
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<p lang="en-US" style="margin-bottom: 0in">For more clarity on this use asio4all, when changing Pd's block size that reflects on the actual ASIO used buffer.</p>
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<p lang="en-US" style="margin-bottom: 0in">(Pd's pref blocksize is ONLY for ASIO and has nothing to do with your patch blocksize)</p>
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<p lang="en-US" style="margin-bottom: 0in">Try Pd's pref blocksize to 256.</p>
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<p lang="en-US" style="margin-bottom: 0in">After that check the current scarlett ms numbers.</p>
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<p lang="en-US" style="margin-bottom: 0in">Did it change? And is now controled by Pd?</p>
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<p lang="en-US" style="margin-bottom: 0in">This may require restarting Pd and possible restart of the soundcard.</p>
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<div id="Signature"><font face="Courier New, Courier, Monospace" size="2">Mensaje telepatico asistido por maquinas.</font>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Pd-list <pd-list-bounces@lists.iem.at> on behalf of Christof Ressi <christof.ressi@gmx.at><br>
<b>Sent:</b> Monday, February 20, 2017 11:24 PM<br>
<b>To:</b> pd-list<br>
<b>Subject:</b> [PD] Pd + ASIO</font>
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<div class="PlainText">Hi, <br>
<br>
I've started porting a Pd project to C++ and I'm working with the RtAudio library to interface with my soundcard (Focusrite Scarlett 6i6). There I noticed that I get a *much* better performance than in Pd regarding audio IO. I can play several thousand sawtooth
tones with a blocksize of 1 and a buffer size of 64 samples (~ 1ms in my ASIO settings) and still get a clean and stable output on my Lenovo L440 laptop. In Pd, on the other hand, I get dropouts on a single testtone when I put the ASIO latency down to the
same value. The 'delay' setting in Pd is 20ms - which is quite generous - so for me it's clearly an IO problem. I don't know if the reason is Pd or rather portaudio, though.
<br>
<br>
The Focusrite Scarlett interfaces are 'special' in a way that they only let you choose a latency in ms, which is pretty annoying in some circumstances.
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<br>
I noticed some things when playing around with RtAudio:<br>
<br>
If you requeste a buffersize (via RtAudio::openStream) which is *smaller* than the current latency set in Scarlett MixControl (in ms), it will pick that latency instead and you get strange buffersizes like 442 samples (~ 10 ms). If your requested buffersize
is *greater*, you get this very buffersize.<br>
<br>
Regarding performance: choosing 1 ms in MixControl and requesting 64 samples via RtAudio works beautifully, but in Pd I cannot achieve any decent and stable IO with the same latency setting.
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I don't know if I'd go so far and say that ASIO is broken in Pd, but on some soundcards it's definitely not working well. I have the suspicion that Scarlett's odd latency setting might be the culprit. But I remember that I also had bad results with an RME babyface.
I have to check again, though.<br>
<br>
Does anyone have more insight in how Pd communicates with portaudio when using ASIO? How is the ASIO buffersize being handled? What are your experiences with latency settings for Pd + ASIO?
<br>
<br>
Christof<br>
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