What P-frame interval does Premiere use for exporting H.264?

[Angelo Lorenzo]

So far as I know, GOP structure is controlled by profile level.
Baseline: no b frames
Main: IBBBP
High: IBBP

https://www.eventdv.net/Articles/ReadArticle.aspx?ArticleID=80446

——————–
Angelo Lorenzo

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[Ivan Myles]

Great info. Thanks!

[Angelo Lorenzo]

Actually, it may be
Main: IBBP
High: IBP

https://mediainfo.sourceforge.net/en Media info is showing 2 reference frames for Main, 1 for High… it’s a good place to start.

——————–
Angelo Lorenzo

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[Ivan Myles]

Thanks for the tool. It’s showing the same GOP structure with M=1 (IBP) for both Main and High profiles at Level 5.1.

Format/Info : Advanced Video Codec
Format profile : Main@L5.1
Format settings, CABAC : No
Format settings, ReFrames : 2 frames
Format settings, GOP : M=1, N=12

Format/Info : Advanced Video Codec
Format profile : High@L5.1
Format settings, CABAC : No
Format settings, ReFrames : 2 frames
Format settings, GOP : M=1, N=12

[Ivan Myles]

[Ivan Myles] “It’s showing the same GOP structure with M=1 (IBP) for both Main and High profiles at Level 5.1.”

To correct my previous post, M=1 corresponds to an IP structure with no B-frames. MediaInfo defines M as the distance between two anchor frames (I and P). I previously thought it was the AME definition of the number of B frames between anchor frames.

So it appears Premiere Pro does not use B-frames for H.264 exports.

[Angelo Lorenzo]

You might be premature in this. It appears to be controlled by profile, as I originally mentioned.

Tested a 3 second file with a keyframe distance of 12

Baseline@L4.0
M=1 N=12
IPP…

Main@L4.0
M=4 N=12
IBBBP…

High@L4.0
M=3 N=12
IBBP…

——————–
Angelo Lorenzo

Need to encode ProRes on your Windows PC?
Introducing ProRes Helper, an awesome little app that makes it possible
Fallen Empire Digital Production Services – Los Angeles
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[Ivan Myles]

Perhaps my comment should be qualified to read, “So it appears Premiere Pro does not use B-frames for H.264 exports when bitrate is not a constraint.” I am encoding with target bitrate maximized, and the generated files don’t have B-frames. Maybe the encoder just uses P-frames when there is ample bitrate available.

[Angelo Lorenzo]

Strange, mind sharing your Premiere Pro encoder settings?

My previous results were CBR, low bitrate, I think 5Mbps. I tried CBR with an obscene 60Mbps as well as VBR with 60-90 Mbps as the range, and I was still getting the same M=4 and M=3 results.

——————–
Angelo Lorenzo

Need to encode ProRes on your Windows PC?
Introducing ProRes Helper, an awesome little app that makes it possible
Fallen Empire Digital Production Services – Los Angeles
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Fallen Empire – The Blog
A blog dedicated to filmmaking, the RED workflow, and DIT tips and tricks
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[Angelo Lorenzo]

Check your multiplexer settings. If it’s set to anything other than standard you’ll have issues. iPod multiplexing will remove b-frames at every level.

——————–
Angelo Lorenzo

Need to encode ProRes on your Windows PC?
Introducing ProRes Helper, an awesome little app that makes it possible
Fallen Empire Digital Production Services – Los Angeles
RED transcoding, on-set DIT, and RED Epic rental services
Fallen Empire – The Blog
A blog dedicated to filmmaking, the RED workflow, and DIT tips and tricks
Can your post production question fit in a tweet? Follow me on Twitter

[Ivan Myles]

[Angelo Lorenzo] “Check your multiplexer settings. If it’s set to anything other than standard you’ll have issues. iPod multiplexing will remove b-frames at every level.”

That was it. Somehow the multiplexer stream compatibility was set to iPod. I must have inadvertently hit a preset at some point. Thanks!