[Linphone-developers] osscard.c patch for strongArm and reduced delay

[Doug Blewett]

I have been using linphone on an odd strongArm
architecture with a cs4232 chip under linux
2.6.6 - heavily modified port.  I am using oss
rather than alsa - mainly history.

To get linphone-1.0.1 (libosip2-2.2.0) to work I
had to modify osscard.c in a couple of places.
This may help other users and/or developers.

I changed the bsize to 512 bytes in open and
probe and added the following bit of fragment
code.  These two modifications greatly improve
(reduce) audio delay:

        /*
         * Frame size
         */
        p = ((128<<16) | 7);    // 128 frags, 2^7 = 128 bytes each
        if (ioctl(fd, SNDCTL_DSP_SETFRAGMENT, &p) < 0) {
                g_warning("oss_open: SNDCTL_DSP_SET_FRAGMENT %s",
                          strerror(errno));
        }

I also commented out the following as it tended
to killed my card:

/*
    {
      int fl,res;

      fl=PCM_ENABLE_OUTPUT|PCM_ENABLE_INPUT;
      res=ioctl(fd, SNDCTL_DSP_SETTRIGGER, &fl);
      if (res<0) g_warning("OSS_TRIGGER: %s",strerror(errno));
    } 
*/      

I am willing to send in my complete copies of
osscard.c (from both directories) to any one who
wants them.

I should mention that linphone works great
especially on these small embedded
systems. Awfully nice of Simon and all who have
contributed.

Doug Blewett
AT&T Labs Research