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Timecode breaks in Rendered MPEG2
Hey guys,
I’ve just come upon a rather unusual problem.
Scenario:
I’m rendering out a TVC for broadcast. I’m using CS6. There is a single linked After Effects file in the Sequence. I’m rendering it out as MPEG2, 30 MB/s (CBR), top field first, MPEG2 Audio at 48khz and 16 bits. I’ve done this several times in the past, and have had TVC’s pass broadcasting QC without any problem.For the first time today, I had one of the guys at the reseller get back to me and tell me
“Your timecode had multiple breaks in it so when we put it through our system it was showing it was 4 frames short.”
Now I understand timecodes. I understand how breaks can cause an error when logging and capturing etc. What I don’t get is how did this 15″ TVC that I render end up with multiple timecode breaks? The sequence starts at 0:00:00 and goes to 0:14:24, with the duration obviously being 15″ (@25fps of course).
How can I check for timecode breaks in my rendered sequence? What can I do to avoid them in the future? And how in the world did they get into the rendered sequence in the first place?
Many thanks
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2 Replies
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HAve you watched the encoded file from front to end and does everything seem normal in the picture. You should also ask if QC can provide you with the exact frame where the TC breaks.
My guess is it is probably something simple but impossible to troubleshoot without more info. You could try to do a pass with a slightly lower bitrate as a data spike could possibly break the timecode stream but that is unlikely.
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Hi Kris,
Thanks for your reply. I’ve played the rendered out media frame by frame, and I’ve checked the metadata on it and everything seems fine.
There’s a little more information that just came my way. So with the first version of this TVC I submitted I was told there was a luma spike in one of the frames (my bad for letting it slip past me). So I re rendered the TVC with the luma spike fixed. Now what the guy at the reseller is telling me is that he could put the first version of the TVC with the luma spike through his system with no timecode breaks. However, the second render, the one with the luma spike adjusted couldn’t be put through because there were multiple timecode breaks.
The way I finally got around it was by exporting an uncompressed image sequence, and then replaced all the video clips in the timeline with the image sequence and rendered out a third version which has now been accepted and put through their system.
I’m just really curious as to how that could have happened. Definitely will hit them up today and see if I can get exact frames where the timecode breaks.
Cheers
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