Re: Glitch-free presentations with Windows 7 and Matlab (Etienne Gaudrain )


Subject: Re: Glitch-free presentations with Windows 7 and Matlab
From:    Etienne Gaudrain  <egaudrain.cam@xxxxxxxx>
Date:    Tue, 18 Oct 2011 18:46:12 +0100
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Hi, Unless someone has found the solution (I can't recall), there's another issue with Windows 7 which is that the mixer interface is unbelievably complicated and it is a nightmare to set the sound level. If I'm correct that nobody has provided a solution to this problem as yet, this is another good reason to stick to good old XP. Note that the issue also sometime arise with ASIO drivers in WinXP as well because the ASIO volume isn't always linked to the Windows' mixer volume. Otherwise, another alternatives is to play sounds through TDT Systems. But again we are far from the simple "sound" function in Matlab (although I don't see why anyone would like to use this when the audioplayer object offers so much more flexibility). -Etienne PS: Trevor, I guess you've seen this: http://www.playrec.co.uk/forum/viewtopic.php?id=209 and other entries in this forum: http://www.playrec.co.uk/forum/viewforum.php?id=4. On 18/10/2011 16:52, Trevor Agus wrote: > I've found it surprisingly difficult to present glitch-free sounds with > Windows 7. > > The short answer is that Padraig Kitterick's "asioWavPlay" seems to be the > simplest reliable method (remembering to buffer the waveforms with 256 samples > of silence to avoid truncation issues). For those with more complex needs, > perhaps soundmexpro or PsychToolbox would be better. I'd value any second > opinions and double-checking, so a review of the options follows, with all the > gory details. > > I've been using a relatively old version of Matlab (R2007b) with a Fireface UC > soundcard. If the problems are fixed in another version or soundcard, I'd love > to know about it. > > ===Matlab's native functions (sound, wavplay, audioplayer) > Large, unpredictable truncations were the least of our problems. We also often > got mid-sound glitches, ranging from sporadic (just a few subtle glitches per > minute) to frequent (making the sound barely recognisable). The magic formula > for eliminating the glitches seemed to be to keep the soundcard turned off > until > the desktop was ready, with all background programs loaded. (Restarting either > the soundcard or the computer alone guaranteed some glitches.) So this formula > seems to work, but it's a bit too Harry Potter for my liking, and the spell > might change with the next Windows update. I think I read that Fireface were > no longer supporting Microsoft's vagaries, and they recommended using ASIO. I'm > not sure if other high-end soundcard manufacturers are any different. Since > Matlab's native functions don't support ASIO (unless the new versions do?), > I think we're forced to look at the ASIO options. > > ===playrec > This seems to be potentially the most flexible method of presenting sounds but > I've hit a brick wall compiling it for Windows 7. I think its author stopped > providing support for it a few years ago. Has anyone had more success than me? > > ===asioWavPlay > This simply presents a .wav file using ASIO. It's a little annoying that you > have to save your sound to disk before presenting it, but as Joachim pointed > out, it's not too difficult to automate this process. While doing that, I add > 256 samples of silence to the end to work around the truncation problem. > > ===pa_wavplay > This is nearly the perfect solution except (1) the number of samples truncated > from the end is slightly unpredictable and (2) it prints a message on the > screen after every sound ("Playing on device 0"). For these two reasons, I > prefer asioWavPlay. > > ===soundmexpro > This might be best choice for the high-end user (I've just had a quick look at > the demo version today). It's easy to install and there are good tutorials, but > it involves initialising sound objects, etc. -- it's not just a replacement for > Matlab's "sound" command. Also it looks like it's €500+. > > ===PsychToolbox > Originally designed for visual experiments, PsychToolbox has now got quite > extensive low-latency sound functions, including realtime continuous > playing/recording. It's also free. However, it's slightly challenging to > install Like soundmexpro, it's object-oriented -- so don't expect to play a > sound with a simple one-liner. > > ===PortAudio > Most of above programs are based on this C library. If you're an experienced > programmer, perhaps you'd prefer to go direct the source? And while you're > there, perhaps you could write the perfect Matlab-ASIO interfaces for the rest > of us? (Please!) > > Has anyone found a simpler solution? I'd be glad to hear it. > > Trevor -- Etienne Gaudrain, PhD MRC Cognition and Brain Sciences Unit 15 Chaucer Road Cambridge, CB2 7EF UK Phone: +44 1223 355 294, ext. 645 Fax (unit): +44 1223 359 062


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