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What’s going on when Premiere Pro is “Conforming” new media and can I stop / alter this?
I get this may be a silly question, but here’s the deal:
Say I have an old school SD (DV NTSC) timeline. And I’ve found some random B-Roll from a different codec / file type — like an H.264 MP4.
Upon import on the timeline, PP will automatically start “conforming” the different codec as indicated on the bottom right corner the timeline with a yellow bar.
What I want is for PP to NOT create more files, except tiny reference files, like waverform caches. I was under the impression that the “Mercury Playback Engine” could handle H.264 “on the fly” so it wouldn’t have to create extra cache or transcodes.
However, when I import new media — H.264, XVID, XDCAM, Whatever Codec — PP writes stuff to the designated Media Cache Files Folder, which I believe are Preview Files into these particular extensions: .ims, .pek. cfa, and .qtindex
Most are fairly small files. But the .cfa file can be enormous. For instance, if I have an H.264 MP4 that is 800 MB the .cfa PP creates might be 3.5 GB! This seems like a huge waste of space and CPU cycles. And I can’t edit at a decent speed while it is “conforming” this file.
I don’t really want to take up all this space and have PP transcoding in the background. I’m new to PP (switched from FCP7) and one of the (many) reasons I especially didn’t choose FCPX was because it’s “always” rendering in the background. I just want to start editing and not do any rendering or “conforming” until I’m ready to export.
Does anyone know how to disable creating these rather larger cache files — especially the .cfa files that take so much space and time to create?
Is there something I’m missing?
Any insight is much appreciated. Thanks in advance.
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4 Replies
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Premiere generates .cfa files because it conforms the audio from the video clip for faster audio processing. It’s a large file because it holds a number of different types of audio streams including AC3, LPCM, and DVD subtitles.
No, you cannot disable or skip this process. It has been a common complain for years, but Adobe probably prefers doing it this way to minimize audio rendering and to help squeeze performance from slower workstations.
I have CCleaner on my windows machine and I it set to clear out any cfa file older than two months. It makes opening older projects a pain, but it keeps space free on my drives as new projects roll in.
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Yes, to clarify, this is AUDIO conforming, not video. Adobe can handle H.264 on the fly, and it’s not a matter of handling the video codec, but of the variance in sample rate of audio. ALL editing programs need to have their sample rates the same before mixing audio files – FCP just did it in the eternally unrendered audio in the timeline (*BEEP*BEEP*) – Adobe does it on import so you never have to think about it again.
Every time you delete the files, new ones will be created. As Angelo said, you can (and perhaps should) clean out old files, but then it will take a long time to restart old projects. I just set them to generate in the same directory as the media, and then they just always travel with the media files.
It’s just sort of something that I’m come to expect when importing a huge amount of footage into a project – it slows down a little bit, but as soon as you hit “play” conforming halts and waits. If it really bugs you, just import a chunk, go to the bathroom, and it’s usually done by the time you get back.
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It seems the vaunted Mercury Playback engine could conform audio realtime with it’s eyes closed, another item for the wish list. We basically don’t want to have to wait for any thing, even those audio waveform files either. Maybe an option if you really need to get more performance, but if you have a fast machine, which you most likely would have if you got Premiere Pro for the MPE, just do it all realtime!
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Thanks for the replies.
This is helpful and ironic.
Firstly, I do think the Mercury Playback Engine ought to be able to decode compressed audio (usually AAC) in realtime without rendering out a media file. So yes, I will defiantly put in a feature request to Adobe.
But the problem and irony is:
1) We edit media over a network using Apple’s AFP over Ethernet and share media directories across multiple projects. So having all the conform files next to the originals will not work across multiple projects on the network AND it will be tough to navigate with all those tiny files next to master media we need to pull all day long.
2) As ridiculous as FCPX is — and we are not using it — it does edit compressed audio without rendering or conforming. Go figure.
I wonder if Avid does the same thing or if their new playback engine can edit all files / codecs on the fly…
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