Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion.

Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules.

 

Go Back   Doom9's Forum > Video Encoding > MPEG-4 AVC / H.264

Reply
 
Thread Tools Search this Thread Display Modes
Old 11th June 2020, 16:57   #1  |  Link
vin97
Registered User
 
Join Date: Jul 2012
Posts: 3
VFR to CFR conversion without re-encoding?

Is there a way to convert variable framerate H.264 videos to constant framerate without re-encoding?
So detecting duplicate or dropped frames and adjusting the metadata (if that's the right word) accordingly.
I'm talking about relatively small variations in framerate here (approx. between 59.5 and 60fps).
vin97 is offline   Reply With Quote
Old 11th June 2020, 18:35   #2  |  Link
poisondeathray
Registered User
 
Join Date: Sep 2007
Posts: 4,622
Quote:
Originally Posted by vin97 View Post
Is there a way to convert variable framerate H.264 videos to constant framerate without re-encoding?
So detecting duplicate or dropped frames and adjusting the metadata (if that's the right word) accordingly.
I'm talking about relatively small variations in framerate here (approx. between 59.5 and 60fps).
You edit the timecodes as constant . But if it's minimally variable, it can go slightly in and out of sync in sections, but it's probably negligible for your example

eg. You can do this with mkvtoolnix / mkvmerge for mkv , or mp4fpsmod for mp4
poisondeathray is offline   Reply With Quote
Old 12th June 2020, 00:56   #3  |  Link
vin97
Registered User
 
Join Date: Jul 2012
Posts: 3
Thanks!

I guess I will just set the framerate as to match the audio duration then to be safe.
vin97 is offline   Reply With Quote
Old 15th June 2020, 00:04   #4  |  Link
benwaggoner
Moderator
 
Join Date: Jan 2006
Location: Portland, OR
Posts: 3,627
Quote:
Originally Posted by vin97 View Post
Thanks!

I guess I will just set the framerate as to match the audio duration then to be safe.
It depends on why the source is VFR. Sometimes VFR has all the frame rates at a multiple of the base fps. So if there are five identical frames, VFR might have a single frame with 5x the default duration. In CFR, the frames are all the same duration, and the repeated frame would be followed by 4 frame_repeat tags. The right solution would be to convert long duration frames into that frame followed by repeat frames. If that's the case with your content, spreading the fps over the whole file can cause some obvious lip sync issues.

If it is VFR because 1 out of 120 frames getting randomly dropped, evening out the frames would work better.
__________________
Ben Waggoner
Principal Video Specialist, Amazon Prime Video

My Compression Book
benwaggoner is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 03:25.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.