[gst-devel] Audio visualizations

Matteo Landi landimatte at gmail.com
Tue Jul 27 17:53:10 CEST 2010

Hi guys,
these days I was wondering how to use gstreamer in order to create
some audio visualizations like an oscilloscope or a spectrum analyzer.

The application consist of a window with a drawing area used to
display the visualizations.
Regarding the pipeline, I thought about something like

filesrc !
decodebin !
audioconvert !
audio/x-raw-int, channels=1, rate=44100, width=16, depth=16, endianness=1234 !
tee name=t !
  queue !
    fakesink name=fakesink signal-handoffs=true t. !
  queue !

with the handoff callback linked to a method which spawn a new thread,
process the signal, and queue a redraw of the window.

I got few problems with the implementation:
1 - I often get core dumped, and I cannot understand why: all the
drawing actions are done inside the main thread, so it should be ok
2 - Synchronization between audio and video: the two sources are not
synchronized.. maybe is it something related to the queues elements?

Have you got any advices regarding the chosen implementation, and how
to solve the listed problems?

Thanks in advance for the attention.

Matteo Landi

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