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ClipWrap, rewrapped file sizes increasing by differing amounts
I ran into an issue that Colin helped me resolve, summarizing here in case someone else runs into it.
I had a ~2hr event shot with two cameras, both running single continuous takes. Both shoot MTS files containing h264 video, segmented into 4.29GB chunks. Normally I join and rewrap the files from each camera using ClipWrap, then delete the originals. In this case however, I noticed that although the original MTS files were almost the same size (21.95GB and 22.01GB totals), the rewrapped versions were very different: 26.4GB vs 22.7GB. Both seemed to play back normally, and were only a few seconds apart in duration. I'd noticed that files tend to grow by some amount when rewrapped, and was concerned that maybe the smaller file had somehow dropped ~4GB of information (worryingly, about the same size as the individual video segments).
The problem turned out to be that one of the cameras was shooting stereo audio, and the other was using 5.1 surround. Compressed in the original wrapper they were the same size, but when converted to Linear PCM during rewrapping, the 5.1 grew substantially where the stereo did not. I only ever used the stereo output (coming from a nice external mic), so hadn't cared that the default on-camera mic on the other unit was set to 5.1.
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March 9th, 2013, 09:23 PM
