Hi, I created my own ALSA machine kernel driver for a custom TLV320AIC23 codec based soundcard I built on a breadboard. (Note that I just created the machine driver, I did not change anything in the codec driver itself.) The "soundcard" is connected to an Olimex Sam9-L9260 evaluation kit with an ARM9 AT91SAM9260 CPU on it: http://www.olimex.com/dev/sam9-L9260.html Now comes the interesting part: I got sound playback and recording working on the board. However, there are two strange problems I cannot explain right now: After loading the ALSA machine driver module I wrote, one can play sound with aplay. However, recording does not work, it just records some background noise. Obviously, I enabled all microphone inputs in alsamixer. I can hear myself pretty clear if I talk into the microphone, but I cannot record it. Also, the VU meter which appears if one starts arecord with the -vv flags is between 1% and 2% all the time. After a short chat on freenode in #alsa, the following solved the problem: ------------------------------------ # amixer set 'Mic Input',0 on # amixer set 'Mic',0 cap on ------------------------------------ After that I can record and play sound just fine. Also the VU meter is moving just fine and the recording is loud and clear. * How come that I cannot make these settings in alsamixer ? * Is it possible that there are some controls available through amixer, but now through alsamixer ? The next problem is that while recording, I seem to get buffer overruns: ------------------------------------ # arecord -f cd -vv recording.wav Recording WAVE 'recording.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo Plug PCM: Hardware PCM card 0 'sam9l9260' device 0 subdevice 0 Its setup is: stream : CAPTURE access : RW_INTERLEAVED format : S16_LE subformat : STD channels : 2 rate : 44100 exact rate : 44100 (44100/1) msbits : 16 buffer_size : 8192 period_size : 2048 period_time : 46439 tstamp_mode : NONE period_step : 1 avail_min : 2048 period_event : 0 start_threshold : 1 stop_threshold : 8192 silence_threshold: 0 silence_size : 0 boundary : 1073741824 ## + | 60%overrun!!! (at least 1755605307.470 ms long) Status: state : XRUN trigger_time: 519.572774859 tstamp : 520.141848901 delay : 0 avail : 8192 avail_max : 8192 ############ + | 55%overrun!!! (at least 1755605209.897 ms long) Status: state : XRUN trigger_time: 535.531210229 tstamp : 536.2782850 delay : 0 avail : 8192 avail_max : 8192 # + | 03%^C Aborted by signal Interrupt... ------------------------------------ The root-filesystem of the board is mounted over NFS and it seems that the ethernet driver of the board has some problems so that the connection is slow (like 300kb/s or so). * Is it possible that this is the reason for the overflows, or is it an ALSA problem ? ------------------------------------------------------------------------------ Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT is a gathering of tech-side developers & brand creativity professionals. Meet the minds behind Google Creative Lab, Visual Complexity, Processing, & iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian Group, R/GA, & Big Spaceship. http://www.creativitycat.com _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
