cvs commit: src/sys/dev/sound/pcm dsp.c

[Ariff Abdullah]

ariff       2005-11-14 18:20:47 UTC

  FreeBSD src repository

  Modified files:
    sys/dev/sound/pcm    dsp.c 
  Log:
  From luigi:
          In SNDCTL_DSP_SETFRAGMENT, if you specify both read and
          write channels, the existing code first acts on the
          read channel, but as a side effect it updates the
          arguments (maxfrags, fragsz) passed by the caller according
          to acceptable values for the read channel, and then uses the
          modified values to act on the write channel.
          The problem with this approach is that, given a
          (maxfrags, fragsz) user-specified value, the actual
          values computed by the read and write channels may differ:
          e.g. the read channel might want to allocate more fragments
          than what the user specified because it has no side-effects
          on the delay and it helps in case of slow readers,
          whereas the write channel needs to use as few fragments
          as possible to keep the audio latency low (very important
          with telephony apps).
  
          This patch stores the values computed by the read channel
          into temproary variables so the write channel will use
          the actual arguments of the ioctl.
  
          This patch is very helpful with telephony apps such as asterisk.
  
  Submitted by:   luigi
  Approved by:    netchild (mentor)
  
  Revision  Changes    Path
  1.88      +9 -2      src/sys/dev/sound/pcm/dsp.c