BUG: Use Previews....Doesn't Use Previews.

[scrozier]

This workflow has been broken for a long time and I would really love to fix this one. I know this used to be on uservoice but I can't find the old bug. 

Steps:

1. Set sequence preview file to "Apple ProRes 422HQ" or whatever your favorite is. 

2. Render Sequence to full green.

3. Go to Export, Select an H.264 preset, check "use previews"

4. Watch as PrPro doesn't acess a single preview on disk and instead renders the whole timeline from scratch. 

From my current example I have a .png sequence from blender than I've rendered to green in the timeline.

Export->H.264, use previews checked...

Look at windows resource monitor, why is premiere chewing up PNGs when it should just be referencing the preview files I JUST RENDERED. 

.aecache files being acessed for no reason. 

.png sequence being read. WHY. 

[R Neil Haugen]

If you've read any of the information, "Use previews" requires that the preview and export codecs be indentical. Then it simply puts those in the file without re-encoding.

ProRes, an interframe codec, and H.264 use entirely different encoding processes. There isn't any way not to have to re-encode that process you are doing.

Neil

[scrozier]

@R Neil Haugen What you are describing is the "Smart Render" function which is great and useful. Thats not what "use previews" was orignally used for. 

It used to "use previews" no matter the export destination or format. Yes you are "re-encoding it" but what I am hoping premiere does is use the preview files that I have spend the time rendering as the source material instead of going back down to timeline original media. In many cases this should be MUCH faster for anything with heavy effects or AE involved. Yes render and replace exists but this should also work and is much faster as you can just mash enter to get all your pro-res renders in one keystroke. 

Currently my workflow is something like :

1. Export with match sequence settings to get a smart render (this actually works usually these days). We are going ProRes to ProRes.

2. Drop that file into media encoder or ffmpeg (it launches way faster) to render it out to an H.264. 

I'm trying to eliminate step two as it is redundant. I should be able to use the previews within premiere to export out an H.264. That's what use previews SHOULD do (and used to do for the record) and not only be limited to smart renders. 

[R Neil Haugen]

I don't recall it being faster to create say an H.264 export if I had previews in ProRes, which I normally do. But then, my memory could be off of course.

Perhaps @mattchristensen could give us the actual hard info?

Neil

[scrozier]

Its been broken for awhile now. Again, I can't find the old uservocie requests becuase that got nuked and the search function on here is less than stellar but I want to say its been borked since maybe 2018.