Automatic time alignment by signal analysis

Benjamin M. Schwartz bmschwar at fas.harvard.edu
Wed Apr 20 09:50:18 PDT 2011


I often find myself wanting to edit multiple audio streams that were
recorded by separate devices.  For example, I might have a high quality
audio recorder, and a separate consumer videocamera with a low-quality
microphone.  The two devices, being separate, have different start times
and slightly different clock rates.

I would like to align these two tracks automatically based on analysis of
the audio signals' contents.  Does anyone know of a tool that does this?
If not, I am considering writing such a program, as I am interested in the
signal processing problem.

I would like to make this tool as friendly to gstreamer as possible, so
that it can be used in gst-world applications like PiTiVi.  However, I do
not know how to structure the program.  The program must perform analysis
on the entire duration of two different audio streams (potentially
multiple hours or longer) before determining the required offset and
stretch factor.  These parameters then need to be applied, possibly by
editing a gnonlin timeline.

How should I write such a program ... or have you already written it?

--Ben

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