Hi Scott > > I'm glad to hear it. The symptoms were a little strange though, even for > > a TOC issue. Oh well, at least the result is consistent now. > :) > > > > No problem. Even though things appear to be working now you will still > > suffer from the problems I mentioned. You might just be lucky in that in > > this particular case your sources were sufficiently close in frequency such > > that the drift over the 4 minutes of footage wasn't particularly audible. > > As your clips get longer it is guaranteed that your sync will drift unless > > all digital audio recording sources are locked to the same clock. The > > amount of drift (and therefore the maximum clip length before you notice it) > > depends on how close the recorders' clocks were, which is indeterminant > > since there's a temperature dependency in the frequencies. > > Interesting. This drift stuff is a nightmare. Next recording, we'll > sync to a clock source! :)
Yes, it is a pain. Syncing everything to a master clock is the best solution. However, since only high end cameras have an external syncing options and the external clock units themselves can be quite expensive it's often not possible to do this. That in the end is why I use the workflow described eariler; it's a little more time consuming but still a lot cheaper than an externally clockable camera. :) FYI one thing I've thought of doing is making an audio clock generator which locks to the camcorder. The idea is to take the video output from the camcorder (which by definition is locked to the *video* clock) and detect the sync pulses (probably vertical). This will give a 50 Hz signal. This would then be fed into a phase locked loop (PLL) which would generate the 48 kHz clock signal for the audio hardware. It's a good theory but there are issues. It assumes that the PLL can be made incredibly stable; if it jitters any more than the internal clock of the audio interface it will have a negative impact on the recorded audio quality - to achieve this it might be necessary to go into temperature control. It also assumes that the vertical sync pulses out of the camcorder are stable. Unfortunately I've had no time to pursue this further than thinking about it, so I don't know how feasible it is in practice. Some day I might get around to it though. Anyway, we're getting a bit off-topic here. Best of luck with your future projects and feel free to follow up privately on these matters and to let me know how you get on. Best regards jonathan _______________________________________________ Cinelerra mailing list Cinelerra@skolelinux.no https://init.linpro.no/mailman/skolelinux.no/listinfo/cinelerra
