b49P23TIvg
November 11th, 2012, 12:25 AM
OS ubuntu 12.10
Works: arecord, aplay, audacity, solfege---these work!
Developer installed: Furthermore, I found source for and can build aplay.
I'm struggling with the ALSA docs as I write an application to visualize sound. Currently I get the PCM data reading a pipe to arecord . On a loaded computer at high data rate my program lags miserably. I would like to use a memory map directly to libasound. Failing that I'd like an example command line for arecord --mmap , including commands to set up the mapped file.
I assume that alsa would cyclically write to the map without checking to see if the data were read. Then I could use the data on my schedule. The application needs to run with small lag, and also capture high frequencies. Losing contiguous chunks of data is OK as long as I can also capture most of the data in contiguous chunks.
My code is in post 3 of thread
http://forums.devshed.com/python-programming-11/pyaudio-buffer-overflow-errors-926301.html
After the program is designed I plan to write it in a compiled language.
Also, what, please, are the devices in /dev/snd ? The sound devices seem different from the ubuntu release of 2010.
controlC0
controlC29
hwC0D0
pcmC0D0c
pcmC0D0p
pcmC0D1p
seq
timer
I appreciate your time and good guidance,
Dave.
PS. I see that pulse audio and jack may be options. I haven't understood these, either.
update, maybe --mmap doesn't work yet?
$ alsa-utils-1.0.26.6.gf2826/aplay/arecord --mmap /tmp/buffer'
Recording WAVE '/tmp/buffer' : Unsigned 8 bit, Rate 8000 Hz, Mono
arecord: set_params:1192: Access type not available
Works: arecord, aplay, audacity, solfege---these work!
Developer installed: Furthermore, I found source for and can build aplay.
I'm struggling with the ALSA docs as I write an application to visualize sound. Currently I get the PCM data reading a pipe to arecord . On a loaded computer at high data rate my program lags miserably. I would like to use a memory map directly to libasound. Failing that I'd like an example command line for arecord --mmap , including commands to set up the mapped file.
I assume that alsa would cyclically write to the map without checking to see if the data were read. Then I could use the data on my schedule. The application needs to run with small lag, and also capture high frequencies. Losing contiguous chunks of data is OK as long as I can also capture most of the data in contiguous chunks.
My code is in post 3 of thread
http://forums.devshed.com/python-programming-11/pyaudio-buffer-overflow-errors-926301.html
After the program is designed I plan to write it in a compiled language.
Also, what, please, are the devices in /dev/snd ? The sound devices seem different from the ubuntu release of 2010.
controlC0
controlC29
hwC0D0
pcmC0D0c
pcmC0D0p
pcmC0D1p
seq
timer
I appreciate your time and good guidance,
Dave.
PS. I see that pulse audio and jack may be options. I haven't understood these, either.
update, maybe --mmap doesn't work yet?
$ alsa-utils-1.0.26.6.gf2826/aplay/arecord --mmap /tmp/buffer'
Recording WAVE '/tmp/buffer' : Unsigned 8 bit, Rate 8000 Hz, Mono
arecord: set_params:1192: Access type not available