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Compressing to h.264 TWICE

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Nick Heady
Compressing to h.264 TWICE
on Nov 11, 2014 at 3:24:26 pm

I still don't understand completely how compression affects video. For example, let's say I export a file from After Effects to h.264. I then import it into Premiere, add music, then export it again to h.264.

Am I compressing a compressed file and causing further loss in quality? Or is there no loss in quality because the source is matching the output?

Secondly, how could I perform the task of exporting from AE, importing to Premiere for sound editing, then exporting again...how could I do this without a loss in quality from the transfer from AE to Premiere?

Thanks!


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Craig Seeman
Re: Compressing to h.264 TWICE
on Nov 11, 2014 at 3:33:32 pm

Compressing a video always causes loss and compressing twice is more loss. As to how visible depends on a number of factors.

Very simply put, video compression throws out data repeated from frame to frame. Depending on settings and content, it tries to limit visual impact.

As a rule, don't create H.264 GOP as an intermediary for post production work. It's best to work in ProRes or DNxHD or the camera native codec. H.264 compression should only be the last step for distribution.



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Nick Heady
Re: Compressing to h.264 TWICE
on Nov 11, 2014 at 4:53:10 pm

Got it. I'm working with DSLR so it's natively h.264. However, I'd like to keep all the quality when I go from After Effects to Premiere. Dynamic Link is either buggy or just lags too much on my PC. I cannot playback the composition without lagging.

That being said, I know I could export from AE using Animation Codec, but that's a huge file. Is there a better compromise?


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Craig Seeman
Re: Compressing to h.264 TWICE
on Nov 11, 2014 at 5:20:52 pm

Since you do have to recompress your compositing work from AE, you may want to try DNxHD. If you don't have it installed, I believe it's a free download.

It should be in the Avid codecs download.
http://avid.force.com/pkb/articles/en_US/download/Avid-Codecs-LE-2-3-9



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