synchronising audio + video from 2 sources

[audyovydeo]

I got a audio/video file of a seminar from an entry-level camera, shot at 15fps.

somebody recorded the same with an audio recorder, with a much better quality.
I want to dump the first audio track & use the second - that's easy in any NLE app.

But : how do you make sure you sychronise the audio to the video ? I'm trying it the dirty wai of listening to chunks of audio1 and identifying the same on audio2, but it's hard !

anyone got suggestions in this exercise ?


thanks
a/v

[Ghitulescu]

Well, the way it's done in the industry (where the film and the audio are separatelly taken) is to use time codes. In your case only the way you do it now can help.

[audyovydeo]

Well, the way it's done in the industry (where the film and the audio are separatelly taken) is to use time codes. In your case only the way you do it now can help.

Thanks for answering.
Brute force always wins ... ?? ;-)

cheers
a/v

[Ghitulescu]

Brute force always wins ... ?? ;-)

Not necessarily. There are more than 7 billion people and less than 25000 gorillas :), some 1 million years ago was a completely different ratio

[NanoBot]

Try to import both audio tracks into Audacity, available here: http://audacity.sourceforge.net/ . Get the ffmpeg import library for audacity if needed for your sound tracks, which is available here: http://manual.audacityteam.org/index.php?title=FAQ:Installation_and_Plug-Ins#installffmpeg .

Use "file / import / audio" rather than "file / open" to import the tracks, because only the first method will display the waveform of both audio tracks on the same page. Now you can visually inspect both audio tracks for ( nearly ) identical waveforms, like a click, something falling down, a closing door, an explosion or whatever you find usefull. After you found a "good" sound event in one of the files, zoom into the waveforms and locate the cursor directly at the beginning of this event, first in track one, then in track two, and lookup the timestamp, which is shown in the statusbar. By doing so, you can easily calculate the delay needed to sync the second track, by either inserting silence or by cutting a piece at the beginning of the second track.

If you are working with lossy formats, e.g. mp3 or ac3, you may prefer to use Audacity only to determine the correct delay und do the trimming itself with delaycut: http://madshi.net/delaycut.rar . This avoids an additional loss of quality by reencoding the trimmed audio track.

C.U. NanoBot