[Clam-devel] streaming SDIF files

Greg Kellum greg.kellum at gmail.com
Fri Jun 29 04:24:59 PDT 2007

Hi all,

I've been working on resynthesizing audio from a streaming SDIF file.  For
each frame of the SDIF file, I'm outputting the sinusoidal peaks with a
SpectralPeakArray object, the residual with a Spectrum object, and the
fundamental.  I'm then sending these objects to an SMSSynthesis object, and
then sending the output either to my laptops' speakers or to an audio file.

I've been having a problem with artifacts though that seem to be coming from
the overlapping of windows.  My guess is that either a triangular window is
not being applied to the audio windows before they are being overlapped or
that the step-size is not correct.  But even though I've played around with
a lot of different parameter values, I can't seem to make the problem go
away.  Can someone tell me where exactly this overlap-adding is supposed to
be taking place?  Which class is responsible for it?

I've attached a patch which can be used to reproduce the problem.  I've also
added an extra zip, because for some reason SVN doesn't seem to like
including files in a new directory in a patch even though they've been added
to the repository.  The files in the zip should be unpacked in the examples
directory, and they should unpack to a directory called SDIFToWavStreaming.
After compiling the examples, running the command ./SDIFToWavStreamingExe
will print a help message to the command line giving you the order of
arguments needed by this example.  If anyone has a moment to try this, you
could use the following SDIF file to run the example:

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