OfflineRT Woes

On August 18, 2004, in Final Cut Pro, by peterb

I have a problem that I can replicate reliably. If I capture in OfflineRT mode in Final Cut Pro I can generally only capture about 30 seconds of video before I drop a frame.

This has led to me spending hours debugging my camera, film, and every element in my chain other than my computer before reaching the sad conclusion: there’s nothing wrong with my equipment per se. The 867 Mhz Powerbook G4 with 640 Mb of memory is just too slow to capture more than about 30 seconds of OfflineRT video (30 seconds, incidentally, sounding suspiciously like “the amount of time it takes some internal buffer to fill up before it has to page to disk.”) My working theory is it’s not a problem during the ‘true’ capture — after all, I’m able to capture full rate DV just fine — but the extra CPU time spent compressing the frames into photo JPEG is just a tiny bit slower than needed, resulting in hosage.

So, not particularly wanting to buy a new laptop, I arrived at a workaround: turn off “abort capture on dropped frame”. I leave the warnings on, just on principle. I turn the abort back on when I capture at full res.

I know, I know, I’m playing with fire. But what else can I do? I’m addicted to OfflineRT editing. It’s a sickness.

I’ve found precious little information on the net about OfflineRT, and of course nothing useful from Apple about system requirements. So let me turn the question around: is anyone else out there using OfflineRT on a laptop? What model laptop are you using? Do you experience dropped frames?


1 Response » to “OfflineRT Woes”

  1. Peter.

    Two thoughts – are you capturing to the internal drive or a firewire drive?

    Here are my thoughts:
    1) you’re right. FCP has to recompess on the fly and you’re running out of time as it caches video in it’s memory, recompresses to PJPEG and writes the files. A standard DV stream could possibly work as it has no additional compression.

    2) You could capture DV and then recompress to PJPEG after you capture.

    3) There may be a data collision occurring – This is why you ought to have two Firewire connections each on it’s own bus. One on the CPU, a second as a PCMCIA card.

    You know how to get in contact if you have other questions.