Hi to all,
I've been searching the cow, but couldn't find anything. Here's my problem:
I'm editing on an Apple MacPro with FinalCutStudio (last version), I have a BlackmagicDecklink HD Extreme card installed. For audio monitoring and recording I use a presonus firebox (firewire). My problem is that I can't get audio and video in sync. The firebox works with the core audio drivers, so no drivers to modify. I can change the latency in FCP. This changes the offset between audio and the fcp preview, but nothing happens with the monitor connected via sdi to the bmd card. Video and audio are always way out of sync.
The reason this is happening is because the HD Extreme card is running off its own internal clock while your Firebox is also running on its own clock. You have video output and audio output both running on different clocks, hence the AV sync issues.
I checked the Firebox manual and noticed that is has the option to use the SPDIF input as the clock source. If you can somehow convert the AES output of the HD Extreme card to SPDIF and connect that to the SPDIF input of the Firebox, then set the Firebox to use that clock source, you might be able to then use it as the audio output source. No guarantees though but worth a shot.