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Anomalies in rendered timeline when playing back
This may be a known anomaly, but a quick search in the forum didn’t return a hit for me, so I thought I would post my experience for anyone who may be experiencing the same thing.
For quite some time, I have been experiencing unpredictable and erratic results when rendering selected clips in a timeline. I shoot and edit 720p30 and 720p24. The erratic results presented themselves when playing, although scrubbing through with the play curser looked fine. The results included freeze framing, flickering between clips, etc. I could never duplicate the problem twice in the same spot on the same clip. Sometimes, even previously rendered clips that were playing correctly would become “corrupt” when a render took place on the timeline. It seemed that it may happen with more frequency on clips with motion blur and time warping, but I had no data to back that up. It seemed that when I noticed it happening, I could activate the system monitor and see that “used memory” (the blue slice) had completely filled the 8GB pie chart. It was extremely frustrating.
Finally, I noticed a correlation with the render anomalies and one certain setting. Most of the time I edit, I am using an external HD monitor attached to BlackMagic video out (you can see my complete system config in my profile). Occasionally, I wouldn’t use the monitor and set view>external video>off. I noticed that when I have view>external video turned “off”, I NEVER get the render problem. After noticing this, I tested it extensively and always got the same result. So, now I use the external monitor for color grading in Color and for final review of the timeline. When editing, I just remember to turn external video off and use the FCP canvas. So far, the work around has worked flawlessly.
Although I still do not know what the reason is, if you are experiencing the same render anomalies and have view>external video set to “all frames”, try turning it off, delete your render files for that sequence, render again, and I’ll just BET your problems go away.
Hope this helps someone.
Bill Wilson
SunDolphin Productions
Birmingham, Alabama -
3 Replies
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Hi Bill,
For me that sounds like a playing problem. Why do you think render files are corrupted?
Had you tried to open the files with QT player?Mac OX 10.5.2-FC 6.02-QT 7.4.1
G5 2x2Gh 4GbRAM-BlackMagic Extreme
PMBP 17″Core2Duo 4GbRAM-AJA ioHD
JVC DTV-17″
SONY EX-1 . SONY PD170
..and always a big mess on top of the table. -
Hey Rafael,
Yes. I exported to QT and even carried the process all the way to DVD and the anamolies presisted. Deleting the render files, turning off the external video, re-rendering ALWAYS fixes the problem. A response from the Apple site forum suggested checking driver versions for the HD Extreme.Bill Wilson
SunDolphin Productions
Birmingham, Alabama -
I’ve been having very similar problems that persisted even if I exported QT movies (with the intention of importing and overcutting with them… this actually worked in some instances, but was not 100%).
I notice that the more complex my timeline is, the more likely I wil experience trouble with a render.
I mostly work in HD – Uncompressed 10 bit 23.98 – with an AJA Kona 3.
We have seen all kinds of anomalies. Freeze frame renders, black where there should be picture, freeze frames of DIFFERENT clips…
we’ve tried to use a combination of workarounds to solve this.
(Exporting Quicktime movies mostly, but Bill Wilson’s tip of disabling External Video is also helpful).
Currently, we are upgrading the OS to 10.5.3
This was suggested recently by Apple, so we are giving it a go.
We are often wary of upgrading to the latest and greatest, since this can often cause as many new problems as we hope to solve.
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