[Alsa-user] Capturing 0s to buffer. Help Needed

[Pete Barnard]

Hello.� I have a problem capturing sound from my sound card.� I am just capturing a buffer full of Zeros.� Have tried putting my audio input �into both line-in and mic inputs of my sound card but just get zeros.   I have installed ALSA drivers, libraries and utils 0.9.0rc6 �and am using Red Hat Linux 7.2.� My sound card is a Cirrus Logic CS46xx.�� Have run alsamixer and everything is now unmuted.   My /etc/modules.conf is included at the end of this message.� I have loaded the following modules - modprobe snd-cs46xx;modprobe snd-pcm-oss;modprobe snd-mixer-oss;modprobe snd   I have successfully compiled/linked two example programs which are supposed to demonstrate minimum capture, and minimum playback.� I found these on the Internet (“A tutorial on using the Alsa Audio Api”).� I use hw:0,0 as the device argument to both �programs.� The minimum playback example works ok and produces a buzzing sound from �the pc speaker.� However, I have examined the contents of the buffer after the minimum capture program and it is full of 0s!�   I have included the lines of code where the capture is implemented: for (i = 0; i < 10; ++i) { ������� if ((err = snd_pcm_readi (capture_handle, buf, 128)) != 128) { ������������������������������ fprintf (stderr, "read from audio interface failed (%s)\n", ������������������������������������� snd_strerror (err)); ������������������������������ exit (1); ���������������������� }   Before capture, buf[128] contains 128 random values, after capture, buf[128] contains 128 zeros.�   I can’t see think of anything that I’ve done anything wrong so any help/advice will greatly appreciated as I am attempting to write a sound server using ALSA but cannot progress until I have resolved this problem.   Regards,   Pete   #/etc/modules.conf alias parport_lowlevel parport_pc alias eth0 3c59x alias usb-controller usb-uhci alias char-major-10-135 usbcore #alias sound-slot-0 cs46xx #post-install sound-slot-0 /bin/aumix-minimal -f /etc/.aumixrc -L >/dev/null 2>&1 || : #pre-remove sound-slot-0 /bin/aumix-minimal -f /etc/.aumixrc -S >/dev/null 2>&1 || : # ALSA portion alias char-major-116 snd alias snd-card-0 snd-cs46xx # module options should go here   # OSS/Free portion alias char-major-14 soundcore alias sound-slot-0 snd-card-0   # card #1 alias sound-service-0-0 snd-mixer-oss alias sound-service-0-1 snd-seq-oss alias sound-service-0-3 snd-pcm-oss alias sound-service-0-8 snd-seq-oss alias sound-service-0-12 snd-pcm-oss   # end of /etc/modules.conf