Comment 12 for bug 348353

Finally I got it all working including a52 Pulseaudio profiles!

These are the steps on 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(strcmp(u->device_name, "a52") == 0) {
        pa_sink_set_max_rewind(u->sink, 0);
    } else {
        pa_sink_set_max_rewind(u->sink, u->hwbuf_size);
    }
3. Add Colin's patch:
             if (PA_UNLIKELY((sframes = snd_pcm_mmap_commit(u->pcm_handle, offset, frames)) < 0)) {

+ if (!after_avail && (int) sframes == -EAGAIN)
+ break;
+
                 if ((r =
 try_recover(u, "snd_pcm_mmap_commit", (int) sframes)) == 0)
                     continue;
4. Compile and install Pulseaudio with udev support: make and sudo make install
5. Edit /usr/local/share/pulseaudio/alsa-mixer/profile-sets/default.conf: change a52:%f to a52
6. Copy /etc/pulse/daemon.conf to ~/.pulse/daemon.conf and ensure it has uncommented: default-sample-rate = 48000
7. Edit ~/.asoundrc
8. Put in it:
# Encode AC3 -> Directly on hardware
pcm.Filter_A52Encode {
    type a52
    bitrate 448
    channels 6
    card NVidia
}

# Rate Converter to 48kHz, needed for some applications
pcm.a52 {
    type rate
    slave {
        pcm "Filter_A52Encode"
        rate 48000
    }
}
9. Change NVidia to your card's name from: cat /proc/asound/cards
10. sudo alsa reload
11. 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 ...

12. pulseaudio -k
13. pulseaudio -D