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

From: Doug Blewett
Subject: [Linphone-developers] osscard.c patch for strongArm and reduced delay
Date: Sat, 09 Jul 2005 10:46:33 -0400

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",

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

      int fl,res;

      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

Doug Blewett
AT&T Labs Research

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