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h.264 compression falls apart mid-way (in Compressor)

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Paul Dougherty
h.264 compression falls apart mid-way (in Compressor)
on Mar 27, 2011 at 3:12:04 pm

I've been asked to supply a full size Qt of a DVCPRO HD edit I'm doing (1280x1080) to a developer via ftp. For this "placeholder" h.264 was recommended.

I took an Apple Compressor preset (h.264 800k for high-and connections) and modified it to retain the original size (1280x1080). I would like to do the compression independent of my FCP system, so I exported a Current Settings version of my DVCPRO HD edit. to Qt Took this to a MacBook Pro OS 10.6.3 & Compressor 3.5 The result looked ok for about half of the 4 min RT but midway thru (on a slightly more difficult shot than the pretty static average shot) the picture completely fell apart into compression mush. Any idea what is going on here? (Orig Qt uniformly fine)

Thanks,

Paul

This just a footnote, I really don't want to compress on my FCP system, just wanted to try...

I'm trying it again on my FCP system direct to Compressor with a matching setting and it is taking forever with "compressor processing" and what seems like a third cycle of the frame count repeated.


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Craig Seeman
Re: h.264 compression falls apart mid-way (in Compressor)
on Mar 27, 2011 at 4:32:56 pm

If you're using the 800kbps preset that's restricted to 672kbps for video. It's probably low for the content.

It's not quite clear what you're providing the H.264 file for but generally it would be 1280x720 or 1920x1080 square pixels as opposed to the non square DVCProHD 1280x1080 (which displays as 1920x1080).

What were you viewing the compression with, QT7, QT X, VLC, other?



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Paul Dougherty
Re: h.264 compression falls apart mid-way (in Compressor)
on Mar 27, 2011 at 5:54:19 pm

Well thanks for that Craig. I thought I watched it in both QT7, QT X but a restart and a day later I went back to look at the problem file and it play back fine in both, whereas yesterday the first half looked good* and the 2nd half completely fell apart. Yes I spot-checked thru it more than once. Lesson learned, it was (is)hard to believe that the picture completely unraveling twice at the same spot was a playback problem.

Paul


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Craig Seeman
Re: h.264 compression falls apart mid-way (in Compressor)
on Mar 27, 2011 at 6:58:38 pm

Mysterious the way these things happen. Sometimes, when I get really unexpected behavior I just reboot to see if that clears things up. All sorts of strange things can happen ranging from memory leaks to funky temp files, etc.



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