Thanks for your ideas! I didn't know nmon, interesting tool. But unfortunately it shows nothing unusual when a glitch happens, everything seems to be in a steady state: ~5% CPU load and no "Huge Pages". Also, there are no dmesg messages during playback at all. Since low volume output has no glitches at all I think there can't be general problems in that area.
I think it is also safe to exclude the influence of the storage device, because - In the software I'm developing I'm generating random noise with reading from files, purely from a (very fast) random number generator. - The WAV file test is running from a fast SSD. - I/O would be the same for the full amplitude / half amplitude files, and the problem remains 100% reproducible just depending on the volume levels. Regarding swapping ports: The sound device is just an onboard chipset and I have my headphones plugged straight to the mainboard jack plug. In theory there is not much to go wrong in terms of connections. The only components which might be sensible to audio levels are maybe the final hardware mixer or something else deep down in the audio drivers. Kind regards, Fabian On 19 January 2017 at 16:59, James Shatto <wwwshad...@gmail.com> wrote: > Does the playback file exist on a slow storage device? I have a few > usb sticks that pause with cd quality wav files because of the slow > I/O of the device. But the same file compressed to flac or mp3 on the > same storage device will play without pauses. Or the cd quality file > on any "faster" device, even sdhc cards plays without pauses. > > It could be a power management issue and hardware related. Swapping > around the ports that things are plugged into or using a powered hub > can help, sometimes. > > Try running something like nmon when you trigger the issue. With "L" > for cpu, it can be a little more informative. With a blue "w" when > it's waiting on something from the system. Which might indicate > hardware type issues like bus speed or swap usage. Also check dmesg > for indications of hardware issues (iffy connections). > > - James > > > On 1/15/17, Fabian Keller <cont...@guitargeeksvr.com> wrote: >> Hi all, >> >> While developing an audio software based on PortAudio, I discovered a >> surprising problem related to ALSA: I'm getting short pauses in the >> audio playback (sounding like typical buffer underruns) depending on >> the audio amplitude. >> >> As a test, I have generated two wave files containing pure white >> noise. One of them with an amplitude of 0.5 the other one using a full >> range amplitude of 1.0. I'm playing both files with aplay, but I'm >> getting the same behavior with other players and also with the >> software I'm developing: The 0.5 amplitude files plays without any >> issues. But the 1.0 amplitude file plays with short breaks in the >> audio stream. I'm getting about two of these breaks per minute, but >> there does not seem to be a deterministic pattern. I would guess the >> pauses are <100 ms in duration, which is why I was debugging in the >> direction of buffer underruns for many days until I discovered this >> amplitude effect. I have xruns logging enabled, so I'm pretty sure >> this is not related to that. >> >> Do you have any idea what could be causing this? >> >> System specs: >> - Ubuntu 14.04. with the default libportaudio2 (based on the last 2014 >> release) >> - Standard Intel onboard sound: PCH [HDA Intel PCH], device 0: ALC892 >> Analog [ALC892 Analog] >> >> Another test: Amplitude 0.9 also has breaks, so it is not just the >> full range amplitude. >> >> Thanks, >> Fabian >> >> ------------------------------------------------------------------------------ >> Developer Access Program for Intel Xeon Phi Processors >> Access to Intel Xeon Phi processor-based developer platforms. >> With one year of Intel Parallel Studio XE. >> Training and support from Colfax. >> Order your platform today. http://sdm.link/xeonphi >> _______________________________________________ >> Alsa-user mailing list >> Alsa-user@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/alsa-user >> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
