Using previews in final render

[Liveshots]

When you have the project preview set at 1/2 res for quicker playback, then render a timeline preview, does it still render that 1/2 res or go full? I see you can use preview renders in the final product, but if they are only 1/2 res they'll be no good. What do you know?

[Ann Bens]

Renders the full preview files.

Playback does not affect the files.

Using preview files is only usefull if the preview codec is the same as the export codec.

[Liveshots]

Okay thanks. I chose DSLR as my editing mode as I shoot with a GH5. I want to export MP4 - no ProRes or Mov, but there is no MP4 in the video previews fomat list. Closest (as far as I know) is 'I-Frame only MPEG'. So what's my best bet for being able to use this format's previews in an MP4 final export?

I waited 45 for a preview render of a 3minute section, went to export, selected 'Match Sequence Settings' and the unchangeable format is 'MPEG Preview' with no choice of bitrate

[Ann Bens]

If your preview codec is I frame only mpeg its not an option as its a lesser codec.

So dont use previews and dont use match sequence settings when exporting to mp4.

Just pick a preset; you can tweak the settings.

[Liveshots]

Great. Adobe's wonderful 'Smart Render' doesn't work with the most common user-level video format.

[R Neil Haugen]

Sometime it takes some thinking about the formats ... and how they and the included codecs are structured.

Smart previews are designed around intraframe codecs. Those are codecs where every frame is a complete separate frame, only compressed. Thus you can cut the clip anywhere ... any frame ... without losing any information. You "render" a smart preview into the same format/codec as your expected final file. And then Premiere has an exact bit of the final sequence already created, that it can join with other bits or newly encoded clips again of that same format/codec.

But H.264, the format for mp4 you wish to use, is an interframe codec. Those are codecs using the long-GOP file structure. There are only a very, very few complete frames in the file, as for every complete or 'i-frame', there are 9-30 or even more p- and b-frames. What's a p- or b-frame? It's only a data-set of 1)  pixels that will change before the next i-frame; 20 pixels that have changed since the last i-frame; or 3) ... both.

Therefore, you simply cannot 'cut' the media anywhere as the smart preview process does. The program has to find the appropriate i-frames for both the beginning and end of the "clip" as used in the sequence, and compute the missing p/b frames.

So there's no reason really to make "smart previews" work with H.264 encodes ... there's often very little that can be pre-rendered due to the nature of the format/codec you want to use.

Product Support manager Kevin Monahan ... who's also a long-experienced editor/colorist by trade ... notes that if you setup your project for smart previews, and export that full ProRes/DNxHD/R/Cineform file, set to re-import ... it's a pretty quick process. And then you can make H.264 exports from it fairly quickly.

Neil

[Liveshots]

Well I'm not touching ProRes because I'm on a PC. Just to confirm; Work, preview and export in DNxHD etc then re-write a streamable MP4 afterwards. I think I can live with that, just going to have to do some research into the difference between the formats. I've never used them, got no idea what Cineform has to offer DNxHD.
Considering I'm handling UHD MP4s in a 1080p timeline with overlayed images and my final product is going to be an MP4 YouTube 1080p preset, what would anybody recommend? I haven't got the patience to test every format on the list with a stopwatch

[Ann Bens]

If you dont have the time and you dont do broadcast and you do not need a high quality master file just export to mp4 for youtube with no previews.

[R Neil Haugen]

ProRes works great on a PC within Premiere now. Has since the last version series, in fact. I find it amazing that ProRes is now part of my every-day workflow in/out as my BMPCC4K shoots in ProRes, and I just tend to stay there. Including exporting.

Avid's DNxHD/R is a great codec, as is ProRes, they have "flavors" that are very close to each other.

Cineform uses "wavelet" compression, which means that computing up/down resolutions is very fast compared to other codecs. Depending on the flavor used, compression will be around the same as a similar quality ProRes or DNxHD/R flavor. So if you're used to one, stick with it.

The smart-preview, export a DI to reimport process gives you something you can re-edit/re-export fairly easily. Plus the ability to then export in whatever deliverable spec you need fairly quickly also.

Some of the heavy users here actually upload their YouTube/Vimeo in the DI form anyway. It's a bit slower upload but the services take them, and quality may be a bit higher.

Neil

[Ann Bens]

A bit slower???

No, way slower. It takes me 6 hours to upload 15 minutes  of Prores with an upload speed 25 Mbps.

[R Neil Haugen]

My upload speeds are several times higher than that for most sites. Actually haven't checked YouTube upload speed I'm getting in a while. But then, I just set it and go off to something else. So I never note what it's doing ...

Neil