I'm in the process of editing something in Sony Vegas, but have run into an issue where, when I import an .mp4 file, it plays in the preview/clipping window, but when I try to move the cursor (ie, to search through the clip for the moment I want), it goes black and is impossible to recover.
I've used g-Spot to determine the codecs, and they are v: avc1, and a: mp4a - however, what is more strange, is that I have other .mp4 files, with these exact codecs, in the project that work perfectly well.
Without doing my own investigation on your file, I'd suggest that G-Spot may not now be capable of showing the full story.
In another thread GS was discussed as a tool fit for AVI determination. Also GS hasn't been further developed for sometime - checkout the version number you have and when that version was last developed. It could be that MP4 determination isn't deep enough. Do try another freebie, MediaInfo, maybe that will provide more information and you may see an irregularity between those 2 MP4 files.
MP4 has many versions(?) and it could be GS isn't upto determinging the more recent flavours and subsequently the CODEC required to read it on your VEGAS Timeline.
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