[FFmpeg-user] Comparing audio to sync video

Carl Zwanzig cpz at tuunq.com
Tue Dec 18 21:13:10 EET 2018

On 12/18/2018 10:27 AM, Carl Eugen Hoyos wrote:
> 2018-12-18 12:36 GMT+01:00, Joshua Grauman <jnfo-c at grauman.com>:
>> I have two video cameras recording an event 30 minutes long.[...] The audio won't
>> be exactly identical as they are two different cameras, different mics,
>> different locations, but they are both recording an interview, so the
>> audio should be able to be synced. 

So, effectively you have two -different- videos. To a human, they may sound 
and look mostly the same, but really they're different. "be able to be 
synced" does not necessarily imply "easy to be done" here. (If they had the 
same audio feed, it would be much easier. Heck, if they both recorded real 
timecode, it would be almost trivial.)

> Or are you searching for an automated process to get two independent
> video in-sync?

If that's the goal, there needs to be a readily identifiable sound or visual 
marker at the start of the videos as a sync point, then a process to -find- 
those and get a timecode. The process also needs to know what that marker is 
to look for it. There's a non-trivial amount of processing involved to find 
and make the identification.

If this is an occasional task, you're better off opening the two videos in 
an editor and sliding the timelines around so they match.



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