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Vegas 9: skip recompress to mp4?
I tried couple of options to skip recompression and got these results:
1. m2t files rendered to MP4 do not skip the recompression:-(. At least I don’t see the message ‘skipping recompression’. Strange thing is that Sony displays ‘=’ in front of a preset I created that outputs to a MP4 container. Which I thought means skipping recompression if possible. Anyone can confirm this isn’t possible?
2. Only MainConcept encoders allow VBR settings but not the Sony AVC one. However the mainconcept never skips recompression and I also see = sign in 1 preset (but won’t skip either).
3. Opening Sony rendered m2t files in Tmpgenc xpress hangs. Need to investigate if the m2t files are valid (GOP closed properly or other issue?) Also some players show some weird color artifacts playing the file back at the end of some clips
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4 Replies
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> m2t files rendered to MP4 do not skip the recompression
I think you are missing the point of what skipping recompression means. It means physically copying the input frames to the output frames which requires the input and output to be the exact same format. So M2T to MP4 will never work because, by their very nature, they are two different formats and always require recompression to translate from one format to the other. The only way to skip recompression is to go M2T to M2T or MP4 to MP4 but never M2T to MP4.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
It’s the exact same video codec, both are H264. The only difference is the container (MPEG2 vs MP4). Granted audio needs recompression.
I can do this skip video recompression manually without Vegas. E.g. use megui to demux mts and then remux again with MP4 muxer.
I guess I expected that it would be able to skip recompression of just the video codec by itself which is the most intensive. Hopefully next version…
For now a workaround would be to render as m2ts and then remux. Only downside is that I can’t have 2 pass m2ts files that require rerendering (which shows at times quality loss). I can see that’s not trivial since the entire file has to be same settings (but almost all AVCHD files are VBR).
Also anyone knows what the ‘=’ means in front of the template? It doesn’t seem to indicate potential skip recompression. E.g. sadly blu-ray format is still recompressed.
Also the problem that the m2ts output is not always played back properly in some players is worrisome. If anyone has experience with creating bigger m2ts projects let me know. Otherwise I’ll stick to outputting first to uncompressed YUV and use another multi-pass renderer.
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Having the same codec does not always result in skipping recompression. The properties of the codec must also match. I can have h.264 that uses Main profile and a render template that is h.264 that uses High profile and they will not match so recompression is needed. H.264 has so many options that finding an exact match is next to impossible sometimes.
The ‘=’ in front of a template name means that the template has similar resolution and aspect properties as your project. It does not take the codec into account since a project has no codec. This is done so that you can select from several different render formats and see which templates match the project properties.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
It’s exact same codec/profile and video dialog settings: select Sony AVCHD and click custom. Then in system only change ‘format’ (=container). Video settings don’t change. Audio will switch to AAC.
My expectations were simply too high. But I can always remux myself. I’ve done that before succesfully with m2t files (and recompress audio to aac). What I can’t workaround is the encoding quality of frames that require recompression. Too bad they don’t allow 2 pass like mainconcept. This is a big deal to get great quality so I’ll probably go back to uncompressed to YUV and use a 2nd renderer with better capabilities.
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