[PD] timing problems

Frank Barknecht fbar at footils.org
Wed Feb 16 19:46:02 CET 2005

Hallo Miha,


Miha Ciglar hat gesagt: // Miha Ciglar wrote:

> I want to record a performance:
> - I am recording audio directly in my PD patch: writesf~
> - I am filming the performance with an independent video camera.
> I start and stop the camera and the audio recording in PD
> simultaneously At the end, the recording in the camera is 18min
> 29sec long, but in PD, the recording is 18min 11sec, so I can't put
> the picture and sound together...  I am recording everything at
> 48000 kHz, with PD 0.38-2 (windows) I think I am going crazy with
> this problem, because I can't figure out which one is faulty: PD or
> camera Had anyone ever experienced that kind of behavior?

It is neither's fault actually. If you record something, Pd and every
other software will need to know "what time it is".  For that, Pd will
use, what the soundcard says, which is: "This is one sample, and the
time until the next sample is exactly 1/48000 seconds long."  Your
camera also has something like this clock inside, but for sure, both
clocks disagree about "what exactly is 1/48000 seconds".

As Albert Einstein remarked 100 years ago: Everything is relative,
including expecially, what time it is. It is impossible, that without
any means of synchronisation both your camera and your
computer/soundcard/Pd will use the same time reference. 

So you need to synchronize them both, if you want your recordings to
be of the same length, or match sound and image later on in some video
editing software (like Kino or Cinerella on Linux).

 Frank Barknecht                               _ ______footils.org__
             _ __latest track: fqdn _ http://footils.org/cms/show/38

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