Re: Syncing multiple related audio tracks

be aware that there will not only be a time offset between these two
recordings but there MAY also be a SPEED offset. [..] If the clocks
were off by 100 ppm, after 1 hour the time error could be a
significant fraction of a second.

Indeed, that's actually what my (rough) measures show (0.1% drift from
the expected sampling rate). However, I'm processing only short (few
minutes maximum) footage, so I don't know worry too much about that.

Depending upon your purpose, lip sync or stereo image phasing, this
will be significant.

Actually, I'm shooting some video footages while recording the sound
with an external device then I try to merge them using the original
sound track (with poor quality) as a mean to properly lip sync the new
audio track.

If this is critical to you, it would be best if the algorithm could be
made continously adaptive so that it would track and speed
differences.

Maybe this sort of thing could be handled by searching various chunk
(say 1 minutes worth of samples) from one audio track into the other
one, and deducing from the various resulting place how the clock drifted
between the two.

This technique is a common practice in audio production and you may
get more insight asking at rec.audio.pro.

Ok, I will check there. Thanks!

--
Frédéric Jolliton
.

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