Comment 34 for bug 348353

New versions of Pulseaudio will be patched, but in the meantime, here are the revised steps for Ubuntu Lucid 10.04 LTS:

1. Open from Pulse source code: src/modules/alsa/alsa-sink.c

2. Replace: pa_sink_set_max_rewind(u->sink, u->hwbuf_size); with:
if (pa_alsa_pcm_is_hw(u->pcm_handle)) {
    pa_sink_set_max_rewind(u->sink, u->hwbuf_size);
} else {
    pa_log("Disabling rewind for device %s", u->device_name);
    pa_sink_set_max_rewind(u->sink, 0);
}

3. Replace: pa_sink_set_max_rewind_within_thread(u->sink, u->hwbuf_size); with:
if (pa_alsa_pcm_is_hw(u->pcm_handle)) {
    pa_sink_set_max_rewind_within_thread(u->sink, u->hwbuf_size);
} else {
    pa_log("Disabling rewind_within_thread for device %s", u->device_name);
    pa_sink_set_max_rewind_within_thread(u->sink, 0);
}

4. After line: if (PA_UNLIKELY((sframes = snd_pcm_mmap_commit(u->pcm_handle, offset, frames)) < 0)) { add:
if (!after_avail && (int) sframes == -EAGAIN)
    break;

5. Compile and install Pulseaudio with udev support

6. Copy /etc/pulse/daemon.conf to ~/.pulse/daemon.conf and ensure it has uncommented: default-sample-rate = 48000

7. Edit ~/.asoundrc and put in it:
pcm.a52 {
   @args [CARD]
   @args.CARD {
       type string
   }
   type rate
   slave {
       pcm {
           type a52
           bitrate 448
           channels 6
           card $CARD
       }
       rate 48000 #required somehow, otherwise nothing happens in PulseAudio
   }

8. sudo alsa reload

9. Make sure you do not have a ~/.pulse/default.pa or if you do, that it is using load-module module-udev-detect to load Alsa sinks not load-module module-alsa-sink ...

10. pulseaudio -k and pulseaudio -D