[Alsa-user] Playback of captured audio has many errors

[Jan N. <jan...@gm...>]

I can capture sound to a file from a C program. I can play from the file. But
when i try to playback captured audio directly I get many errors. My code is

   while (1) {
    int nread;
    if ((nread = snd_pcm_readi (capture_handle, buf, BUF_SIZE)) != BUF_SIZE) {
    //if ((nread = snd_pcm_readi (capture_handle, buf, can_read)) != can_read) {
      fprintf (stderr, "read from audio interface failed (%s)\n",
	       snd_strerror (nread));
      print_pcm_state(capture_handle, "capture");
      snd_pcm_prepare(capture_handle);
      print_pcm_state(capture_handle, "capture");
      continue;
    }
        
    printf("copying %d\n", nread);

    if ((err = snd_pcm_writei (playback_handle, buf, nread)) != nread) {
      fprintf (stderr, "write to audio interface failed (%s)\n",
	       snd_strerror (err));
      //exit (1);
      print_pcm_state(playback_handle, "playback");
      snd_pcm_prepare(playback_handle);
      print_pcm_state(playback_handle, "playback");
    }
    printf("Wrote %d frames\n", err);
    
  }

I get the output 

copying 2048
Wrote 2048 frames
read from audio interface failed (No such device)
state xrun capture
state prepare capture
copying 2048
write to audio interface failed (Broken pipe)
state xrun playback
state prepare playback
Wrote -32 frames
copying 2048
Wrote 2048 frames
read from audio interface failed (Read-only file system)
state xrun capture
state prepare capture
copying 2048

Both devices are set to 44khz, stereo, 16 bit interleaved with two periods per
buffer, buffer size 2048 frames. I'm obviously doing something wrong, but don't
know what.