[Lumiera] Audio editing

Christian Thaeter ct at pipapo.org
Sun Jul 5 17:15:38 CEST 2009


Ichthyostega wrote:
>> Juan Pablo Bouza wrote:
>>> ...that it didn´t support frame rates with fractions, such as 23.976....
> 
> Christian Thaeter schrieb:
>> Just a note: using floating point for framerates is almost always a bad idea.
>> Rational numbers (numerator/demominator) are much better...
> 
> And additionally, could you please enlighten me what would be the prospective
> use of such a fractional frame rate for audio? For everything I am aware off,
> the frame rate was fixed to a limited set of values dictated by hardware,
> eg. 8000, 44100, 48000, 96000, 192000, etc.
> 
> But maybe I'm overlooking an interesting use case here?

That are sample rates, dunno if one wants to call single audio samples a
frame :)...

Anyway, video frame rates coming into play when one wants to sync audio
with video which was the case here. Even worse, a lot of (consumer)
cameras clock drift depending on temperature, moon-phase and mood, the
audio sample rate is not exactly 48kHz but some Hz more or less (i'd
guess frame rates may drift too). Some people told me that this gives
noticeable audio desyncs depending if the camera was warm or cold. We'll
face endless fun with such things :). I think some automation for
frame/sample rate fine adjustment controling some noise gate
(extend/compact silent phases) or frame drop (or doubling) might be a
forseeable tool to correct that.

	Christian



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