[Alsa-user] e-mu 0204 onset/offset distortions
Hi, I'm trying to set up the e-mu 0204 for psychoacoustics research purposes on Debian Wheezy. When using aplay to play a short (200 ms, or 900 ms) wav file, at the onset and at the offset of the sound there are audible pops and clicks. I'm actually using a GUI program I wrote in pyqt4 that writes the sound to a wav file, and then calls aplay to play it. This program can also output sound through PyAudio (portaudio) and pyalsaaudio. If I play a sound with PyAudio, then there are no pops and clicks at the onset/offset of the sound, however, with PyAudio there are occasional distortions in the middle of the sound. The strange thing is that if I first play some sounds with PyAudio and then switch to aplay, aplay works well without pops and clicks at the onset/offset of the sound. I have the impression that PyAudio is setting some soundcard parameters that make it work well with aplay. If I close the pyqt4 GUI and open it again, the problem with aplay returns. Do you have any idea of what the problem could be, and how it could be fixed? Some additional info. The problem with aplay is present also if I use it from the command line rather than the pyqt4 app. pyalsaaudio has the same problem as aplay, again if I play some sounds with PyAudio and then switch to aplay the problem is fixed, as long as I keep the pyqt4 app open. I have been using the same program with the e-mu 0202 and it has been working without any issues, so I would discard the pyqt4 app as the source of the program. I have tried plugging the 0204 on different USB ports but the problem persists. Thank you for your help, Sam -- Android apps run on BlackBerry 10 Introducing the new BlackBerry 10.2.1 Runtime for Android apps. Now with support for Jelly Bean, Bluetooth, Mapview and more. Get your Android app in front of a whole new audience. Start now. http://pubads.g.doubleclick.net/gampad/clk?id=124407151iu=/4140/ostg.clktrk ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] e-mu 0204 onset/offset distortions
On Sun, 16 Feb 2014, Samuele Carcagno wrote: Hi, I'm trying to set up the e-mu 0204 for psychoacoustics research purposes on Debian Wheezy. When using aplay to play a short (200 ms, or 900 ms) wav file, at the onset and at the offset of the sound there are audible pops and clicks. I'm actually using a GUI program I wrote in pyqt4 that writes the sound to a wav file, and then calls aplay to play it. This program can also output sound through PyAudio (portaudio) and pyalsaaudio. If I play a sound with PyAudio, then there are no pops and clicks at the onset/offset of the You could route the output into the line in input, and record what is coming out of the system and compare it with what you sent. Now you do not expect bit accuracy but you might be able to see something going on. Eg, a DC level mismatch. sound, however, with PyAudio there are occasional distortions in the middle of the sound. The strange thing is that if I first play some sounds with PyAudio and then switch to aplay, aplay works well without pops and clicks at the onset/offset of the sound. I have the impression that PyAudio is setting some soundcard parameters that make it work well with aplay. If I close the pyqt4 GUI and open it again, the problem with aplay returns. Do you have any idea of what the problem could be, and how it could be fixed? Some additional info. The problem with aplay is present also if I use it from the command line rather than the pyqt4 app. pyalsaaudio has the same problem as aplay, again if I play some sounds with PyAudio and then switch to aplay the problem is fixed, as long as I keep the pyqt4 app open. I have been using the same program with the e-mu 0202 and it has been working without any issues, so I would discard the pyqt4 app as the source of the program. I have tried plugging the 0204 on different USB ports but the problem persists. Thank you for your help, Sam -- Android apps run on BlackBerry 10 Introducing the new BlackBerry 10.2.1 Runtime for Android apps. Now with support for Jelly Bean, Bluetooth, Mapview and more. Get your Android app in front of a whole new audience. Start now. http://pubads.g.doubleclick.net/gampad/clk?id=124407151iu=/4140/ostg.clktrk ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user -- William G. Unruh | Canadian Institute for| Tel: +1(604)822-3273 PhysicsAstronomy | Advanced Research | Fax: +1(604)822-5324 UBC, Vancouver,BC | Program in Cosmology | un...@physics.ubc.ca Canada V6T 1Z1 | and Gravity | www.theory.physics.ubc.ca/ -- Android apps run on BlackBerry 10 Introducing the new BlackBerry 10.2.1 Runtime for Android apps. Now with support for Jelly Bean, Bluetooth, Mapview and more. Get your Android app in front of a whole new audience. Start now. http://pubads.g.doubleclick.net/gampad/clk?id=124407151iu=/4140/ostg.clktrk ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] e-mu 0204 onset/offset distortions
From: Samuele Carcagno sam.carca...@gmail.com To: alsa-user@lists.sourceforge.net Date: Sun, 16 Feb 2014 13:36:02 + Hi, I'm trying to set up the e-mu 0204 for psychoacoustics research purposes on Debian Wheezy. When using aplay to play a short (200 ms, or 900 ms) wav file, at the onset and at the offset of the sound there are audible pops and clicks. I'm actually using a GUI program I wrote in pyqt4 that writes the sound to a wav file, and then calls aplay to play it. This program can also output sound through PyAudio (portaudio) and pyalsaaudio. If I play a sound with PyAudio, then there are no pops and clicks at the onset/offset of the sound, however, with PyAudio there are occasional distortions in the middle of the sound. The strange thing is that if I first play some sounds with PyAudio and then switch to aplay, aplay works well without pops and clicks at the onset/offset of the sound. I have the impression that PyAudio is setting some soundcard parameters that make it work well with aplay. If I close the pyqt4 GUI and open it again, the problem with aplay returns. Do you have any idea of what the problem could be, and how it could be fixed? Some additional info. The problem with aplay is present also if I use it from the command line rather than the pyqt4 app. pyalsaaudio has the same problem as aplay, again if I play some sounds with PyAudio and then switch to aplay the problem is fixed, as long as I keep the pyqt4 app open. I have been using the same program with the e-mu 0202 and it has been working without any issues, so I would discard the pyqt4 app as the source of the program. I have tried plugging the 0204 on different USB ports but the problem persists. Coincidentally, I just finished doing some coding for PyAudio and (py)alsaaudio on Debian 7/Wheezy, though I don't use PulseAudio. I also found that PyAudio has pops and clicks characteristic of Xruns (overruns and/or underruns), while AlsaAudio does not. (FWIW, I decided to use AlsaAudio rather than PyAudio, though I coded my program with a constant that makes it trivial to switch between the two.) In another reply, Bill Unruh suggested routing the output through the line input of another card. That is a very good idea and may give you an idea of what's happening with the pops and clicks in the middle of the file with PyAudio. Another idea is to look at the original file to see if it has a DC offset. In my experience, you can get a click at the start or end of a file if the first or last frame has a value very far from zero. If that is the cause of the beginning and ending transients, you might want to consider editing your file to shave off a few frames so it starts and ends very close to zero. Another idea would be to make a short (a few ms) fade-in or fade-out. Another possible issue if if PyAudio vs. AlsaAudio set up the card to different sample rates, one of them using software to resample from the input WAV file to match what they set the card to. HTH Robert -- Android apps run on BlackBerry 10 Introducing the new BlackBerry 10.2.1 Runtime for Android apps. Now with support for Jelly Bean, Bluetooth, Mapview and more. Get your Android app in front of a whole new audience. Start now. http://pubads.g.doubleclick.net/gampad/clk?id=124407151iu=/4140/ostg.clktrk ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] e-mu 0204 onset/offset distortions
Coincidentally, I just finished doing some coding for PyAudio and (py)alsaaudio on Debian 7/Wheezy, though I don't use PulseAudio. I also found that PyAudio has pops and clicks characteristic of Xruns (overruns and/or underruns), while AlsaAudio does not. (FWIW, I decided to use AlsaAudio rather than PyAudio, though I coded my program with a constant that makes it trivial to switch between the two.) Yes, I've noticed this problem with PyAudio with other soundcards as well. In another reply, Bill Unruh suggested routing the output through the line input of another card. That is a very good idea and may give you an idea of what's happening with the pops and clicks in the middle of the file with PyAudio. Thank you and Bill for the suggestion, I did that and it looks like there is a DC offset before and after the sound starts playing, you can see it on this graph: https://dl.dropboxusercontent.com/u/1162239/before_pyaudio.pdf this was obtained by playing a 500-ms 1 kHz pure tone with 10-ms fade in and 10-ms fade out (not obvious from the figure but the fade in and fade out is there) with aplay after I prime the soundcard by playing some sounds with pyaudio, the graph obtained by playing the same sound with aplay looks like this instead: https://dl.dropboxusercontent.com/u/1162239/after_pyaudio.pdf Sam -- Android apps run on BlackBerry 10 Introducing the new BlackBerry 10.2.1 Runtime for Android apps. Now with support for Jelly Bean, Bluetooth, Mapview and more. Get your Android app in front of a whole new audience. Start now. http://pubads.g.doubleclick.net/gampad/clk?id=124407151iu=/4140/ostg.clktrk ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] e-mu 0204 onset/offset distortions
I have never seen that in any of the files I have played. That hints that that is your input stream, rather than some problem with the soundcard itself, although I have also never used your sound card. So to be clear, you recorded onto a .wav file that sound. That .wav file did not have those transients. You then played that file with aplay, and recorded the output, starting the input before the file started playing and ending after it stopped. If so, that is one strange soundcard. On Sun, 16 Feb 2014, Samuele Carcagno wrote: Coincidentally, I just finished doing some coding for PyAudio and (py)alsaaudio on Debian 7/Wheezy, though I don't use PulseAudio. I also found that PyAudio has pops and clicks characteristic of Xruns (overruns and/or underruns), while AlsaAudio does not. (FWIW, I decided to use AlsaAudio rather than PyAudio, though I coded my program with a constant that makes it trivial to switch between the two.) Yes, I've noticed this problem with PyAudio with other soundcards as well. In another reply, Bill Unruh suggested routing the output through the line input of another card. That is a very good idea and may give you an idea of what's happening with the pops and clicks in the middle of the file with PyAudio. Thank you and Bill for the suggestion, I did that and it looks like there is a DC offset before and after the sound starts playing, you can see it on this graph: https://dl.dropboxusercontent.com/u/1162239/before_pyaudio.pdf this was obtained by playing a 500-ms 1 kHz pure tone with 10-ms fade in and 10-ms fade out (not obvious from the figure but the fade in and fade out is there) with aplay after I prime the soundcard by playing some sounds with pyaudio, the graph obtained by playing the same sound with aplay looks like this instead: https://dl.dropboxusercontent.com/u/1162239/after_pyaudio.pdf Sam -- Android apps run on BlackBerry 10 Introducing the new BlackBerry 10.2.1 Runtime for Android apps. Now with support for Jelly Bean, Bluetooth, Mapview and more. Get your Android app in front of a whole new audience. Start now. http://pubads.g.doubleclick.net/gampad/clk?id=124407151iu=/4140/ostg.clktrk ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user -- William G. Unruh | Canadian Institute for| Tel: +1(604)822-3273 PhysicsAstronomy | Advanced Research | Fax: +1(604)822-5324 UBC, Vancouver,BC | Program in Cosmology | un...@physics.ubc.ca Canada V6T 1Z1 | and Gravity | www.theory.physics.ubc.ca/ -- Android apps run on BlackBerry 10 Introducing the new BlackBerry 10.2.1 Runtime for Android apps. Now with support for Jelly Bean, Bluetooth, Mapview and more. Get your Android app in front of a whole new audience. Start now. http://pubads.g.doubleclick.net/gampad/clk?id=124407151iu=/4140/ostg.clktrk ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] e-mu 0204 onset/offset distortions
On Sunday 16 Feb 2014 20:47:44 you wrote: I have never seen that in any of the files I have played. That hints that that is your input stream, rather than some problem with the soundcard itself, although I have also never used your sound card. So to be clear, you recorded onto a .wav file that sound. That .wav file did not have those transients. You then played that file with aplay, and recorded the output, starting the input before the file started playing and ending after it stopped. yes, that's correct. Because aplay does play the wav file well after it is primed by playing some sounds with PyAudio, I wonder what PyAudio is doing and whether I could instruct aplay to do the same through some command-line option. Just for completeness I should add that I observed this behaviour with the soundcard plugged on different computers, as well as with the Debian testing branch and the current Ubuntu development branch. I removed pulseaudio before running any of these tests as it has other problems for me: http://lists.freedesktop.org/archives/pulseaudio-discuss/2012-October/014756.html Probably I can circumvent the onset/offset transient issue with a function that automatically plays some sounds with pulseaudio each time my pyqt4 program starts. I will also have to check that the soundcard plays sounds with 24-bit depth. Cheers, Sam -- Android apps run on BlackBerry 10 Introducing the new BlackBerry 10.2.1 Runtime for Android apps. Now with support for Jelly Bean, Bluetooth, Mapview and more. Get your Android app in front of a whole new audience. Start now. http://pubads.g.doubleclick.net/gampad/clk?id=124407151iu=/4140/ostg.clktrk ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] e-mu 0204 onset/offset distortions
On Sun, 16 Feb 2014, Samuele Carcagno wrote: On Sunday 16 Feb 2014 20:47:44 you wrote: I have never seen that in any of the files I have played. That hints that that is your input stream, rather than some problem with the soundcard itself, although I have also never used your sound card. So to be clear, you recorded onto a .wav file that sound. That .wav file did not have those transients. You then played that file with aplay, and recorded the output, starting the input before the file started playing and ending after it stopped. yes, that's correct. Because aplay does play the wav file well after it is primed by playing some sounds with PyAudio, I wonder what PyAudio is doing and whether I could instruct aplay to do the same through some command-line option. Just for completeness I should add that I observed this behaviour with the soundcard plugged on different computers, as well as with the Debian testing branch and the current Ubuntu development branch. I removed pulseaudio before running any of these tests as it has other problems for me: http://lists.freedesktop.org/archives/pulseaudio-discuss/2012-October/014756.html Probably I can circumvent the onset/offset transient issue with a function that automatically plays some sounds with pulseaudio each time my pyqt4 program starts. I will also have to check that the soundcard plays sounds with 24-bit depth. It definitely sounds like a problem with your soundcard. What happens if you put in say 1 sec of silence before the sound starts playing. Mind you that trailing DC really looks suspicious, as if your file has a DC component, rather than the soundcard, but is belied by the fact that if you play it later, it is fine. The DC looks like it is dying away at the beginning, but then it sure should not be there at the end. Cheers, Sam -- Android apps run on BlackBerry 10 Introducing the new BlackBerry 10.2.1 Runtime for Android apps. Now with support for Jelly Bean, Bluetooth, Mapview and more. Get your Android app in front of a whole new audience. Start now. http://pubads.g.doubleclick.net/gampad/clk?id=124407151iu=/4140/ostg.clktrk ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user -- William G. Unruh | Canadian Institute for| Tel: +1(604)822-3273 PhysicsAstronomy | Advanced Research | Fax: +1(604)822-5324 UBC, Vancouver,BC | Program in Cosmology | un...@physics.ubc.ca Canada V6T 1Z1 | and Gravity | www.theory.physics.ubc.ca/ -- Android apps run on BlackBerry 10 Introducing the new BlackBerry 10.2.1 Runtime for Android apps. Now with support for Jelly Bean, Bluetooth, Mapview and more. Get your Android app in front of a whole new audience. Start now. http://pubads.g.doubleclick.net/gampad/clk?id=124407151iu=/4140/ostg.clktrk ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] e-mu 0204 onset/offset distortions
Date: Sun, 16 Feb 2014 14:56:08 -0800 (PST) From: Bill Unruh un...@physics.ubc.ca To: Samuele Carcagno sam.carca...@gmail.com Cc: alsa-user@lists.sourceforge.net On Sun, 16 Feb 2014, Samuele Carcagno wrote: On Sunday 16 Feb 2014 20:47:44 you wrote: I have never seen that in any of the files I have played. That hints that that is your input stream, rather than some problem with the soundcard itself, although I have also never used your sound card. So to be clear, you recorded onto a .wav file that sound. That .wav file did not have those transients. You then played that file with aplay, and recorded the output, starting the input before the file started playing and ending after it stopped. yes, that's correct. Because aplay does play the wav file well after it is primed by playing some sounds with PyAudio, I wonder what PyAudio is doing and whether I could instruct aplay to do the same through some command-line option. Just for completeness I should add that I observed this behaviour with the soundcard plugged on different computers, as well as with the Debian testing branch and the current Ubuntu development branch. I removed pulseaudio before running any of these tests as it has other problems for me: http://lists.freedesktop.org/archives/pulseaudio-discuss/2012-October/014756.html Probably I can circumvent the onset/offset transient issue with a function that automatically plays some sounds with pulseaudio each time my pyqt4 program starts. I will also have to check that the soundcard plays sounds with 24-bit depth. It definitely sounds like a problem with your soundcard. What happens if you put in say 1 sec of silence before the sound starts playing. Mind you that trailing DC really looks suspicious, as if your file has a DC component, rather than the soundcard, but is belied by the fact that if you play it later, it is fine. The DC looks like it is dying away at the beginning, but then it sure should not be there at the end. I agree there's something very odd about the DC segments before and after the tone burst. I think I can just barely see the 10ms fade-in/out. It's a little more apparent when zoomed in. The DC segments look like maybe switching transients while the card is being initialized. Perhaps playing a short piece of silence via PyAudio before playing your real content via AlsaAudio would be the most practical solution for that situation. One other thing I remembered about PyAudio with my program is I see a lot of whining about 'Unable to find definition ...', 'No such file or directory', 'Unknown PCM rear', 'Failed to create secure directory: Permission denied', and so forth with PyAudio during program initialization. With AlsaAudio, there is no such complaining. HTH Robert -- Android apps run on BlackBerry 10 Introducing the new BlackBerry 10.2.1 Runtime for Android apps. Now with support for Jelly Bean, Bluetooth, Mapview and more. Get your Android app in front of a whole new audience. Start now. http://pubads.g.doubleclick.net/gampad/clk?id=124407151iu=/4140/ostg.clktrk ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
