Proxies of variable frame rate footage

[KazuTa]

Do proxies not play back well if the source footage is variable frame rate? I have an old GoPro clip in a 23.976 fps sequence. When I turn on the proxy, it doesn't play back well. The original GoPro footage says it's 30.01 fps (which makes me think variable frame rate). The proxy is 30 fps ProRes Proxy.

The same thing happens with screen record footage for which proxies were made. 

[R Neil Haugen]

It can be an issue. For that I'd go to Handbrake or ShutterEncoder with the original clip, and force creation of a CFR encoding. Replace the VFR in Premiere with that CFR clip.

[KazuTa]

This will eventually be delivered for broadcast. Would it be better to let online handle the frame conversion?

[Ann Bens]

Screenrecording is known for having VFR

If this project is for broadcast you dont want to mess with vfr.

What do you mean by letting online handle the frame conversion.

Use mediainfo to check the frame rate mode (post screenshot in treeview)

MediaInfo

[KazuTa]

By online, I mean the vendor who'll be doing the final online/color. I imagine they have more sophisticated tools for, and knowledge/experience with, frame conversions.

[R Neil Haugen]

I work for/with/teach pro colorists. So I'm comfortable answering your question.

No. Fix it now. It doesn't harm the file whatsoever, it takes a couple minutes, it will edit like butter compared to as-was, and you're not sticking someone else with fixing what they expected the editors to handle.

ShutterEncoder and Handbrake both have options for creating CFR. They can do it to any codec, including back to H.264/5, though if you do, choose low compression/higher file size for keeping visual q.

I'd do ProRes 422 or Lt depending on original bit depth and file size.

And yes most colorist/finisher types will politely not complain. About your sticking them with an H.264/5 VFR file they then have to create a replacement for and add it into the sequence before doing their job ...

But they will go grrrrr .... internally. And probably mention they worked with another um ... (add pejorative here) ... editor. Professionally they won't mention names. But this type of thing does make cross talk among colorists "colorful".

[MyerPj]

Funny, it's still the old Jim Simon thing, always transcode h.264. 🙂

[R Neil Haugen]

It "survives" onto colorists conformed projects in Resolve more  than it used to. But I still don't know a colorist who like working with the stuff.

Abd VFR is a massive no-no ....😉

[MyerPj]

Try running it thru Shutter Encoder, and instead of a Proxy for this file, just create a ProRes file from it, in CFR. 

https://www.shutterencoder.com/en/

ProRes LT might even work well, depending on the bit rates you prefer.

[KazuTa · Accepted solution]

Ironically, we're going to just use the raw footage as "proxies" and let our online vendor do the frame conversion after turnover.

[Shiv9050]

Yeah, variable frame rate footage can cause sync and playback issues with proxies. Converting clips to constant frame rate before making proxies usually fixes it, especially with GoPro or screen recordings that don’t match the timeline’s frame rate.

[KazuTa]

If it's something that's going to broadcast, we typically leave it VBR and let our online vendor address it, as converting it without knowing exactly what one is doing can introduce weird artifacting.

[R Neil Haugen]

Interesting. Huh. I've converted a lot of  VFR to CFR without ever seeing any artifacts from that ... though long-GOP stuff is prone to artifacting. I've used both Handbrake and ShutterEncoder for the process. Both are 'fronts' for ffmpeg, of course.

Changing bitrates ... going from VBR to CBR, might induce something though. But again, I've done a fair amount without issues. Simply because I haven't paid attention to what the VBR/CBR is on ingesting.

[KazuTa]

Tried to delete my reply but can't anymore. I was on one show where a very experienced AE took VBR into After Effects and did some really complicated stuff to make it look right. Generally, I've left it to people with more of a finishing skill set than me.

[Warren Heaton]

@KazuTa 

Transcoding from variable frame rate to constant frame rate is straightforward.  There's not really anything to mess up.

Have a conversation with your online team about how they want the source footage handled.  It's my experience that anything incorrect about a file means the file gets kicked back.  The frame rate, the scan method, the frame size, the CODEC, and audio settings should be correct.  If you're not sure about the settings you're using, send a test file.  If a spec sheet seems unclear (they're not always well written and sometimes include too much), ask for a file that's at the correct settings that can be used for comparison.

For broadast in the United States, all footage that goes to an online team should be at a correct frame rate (constant 29.97 or constant 23.976).  And an effort is made to not mix these frame rates in the same Timeline.

- Warren

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