[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