After upgrading from kdenlive 0.7.5 and mlt 0.4.4 to kdenlive 0.7.6 and mlt 0.4.6 sound playback stopped working in kdenlive clip playback. Kdenlive displays "SDL failed to open audio. No available sound device.". Sound works in all other applications including the rendered output of kdenlive.

I have a similar problem. I installed Openshot to try it out and it removed debian-alsa now I get the same error message in kdenlive. And it won't let me re-install debian-alsa and if i try to uninstall pulseaudio it wants to uninstall all of KDE as a dependency.

Any thoughts?

Same problem here but found the solution.
I tried openshot in a fresh installation of kubuntu 9.10 after KdenLive 0.7.6 was installed and working properly. After installing (trying) openshot sound in Kdenlive is gone.
"SDL failed to open audio. No available sound device.". When installing openshot libsdl1.2debian-alsa is being removed.

This is what happens when installing openshot:

De volgende extra pakketten zullen geïnstalleerd worden:
libsdl1.2debian-pulseaudio python-mlt
De volgende pakketten zullen VERWIJDERD worden:
libsdl1.2debian-alsa
De volgende NIEUWE pakketten zullen geïnstalleerd worden:
libsdl1.2debian-pulseaudio openshot openshot-docs python-mlt
0 pakketten opgewaardeerd, 4 pakketten nieuw geïnstalleerd, 1 te verwijderen en
22 niet opgewaardeerd.

Appearently the libsdl1.2debian-alsa is being replaced with the pulseaudio package (which s*cks realtime).

Solution: Remove openshot

then run:

sudo apt-get install libsdl1.2debian-alsa

libsdl1.2debian-pulseaudio will be removed automagically and your sound will be restored in kdenlive.

I performed the above and now I no longer get the error but I still get no sound. I've tried several of the audio drivers and when I pick ALSA it gives me the option to pick my audio device, and the one that works isn't there.

Maybe a stupid suggestion, but did you check your volume mixer settings?

Hahaha! It was the PCM channel in my mixer! You're a legend.