[MPlayer-dev-eng] [PATCH] Background video when playing audio-only data

Anders Johansson ajh at watri.org.au
Mon May 5 03:38:17 CEST 2003


> Rich, 
> Please design it :)
> I want this design for a long time. I made a visualization plugin (bars
> plot) but it was never integrated. Ok, it was just a hack, it used to
> block mplayer (was using FIFO to export audio and it's FFT to the
> visualization plugin, which was another program)
> BTW, do you know a beautiful plot method/equation? I can take some time
> do develop the plugins :)

You could start with VU meters, the functionality for measuring the
power level in the audio signal is already in af_volume. You read them
with a control call as

float vu[AF_NCH];
ptr_to_volume->control(ptr_to_volume,AF_CONTROL_VOLUME_PROBE | AF_CONTROL_GET,vu);

look in libaf/control.h. 

I was going to implement an audio filter that could do PSD
measurements (for spectrogram plots), I have the design in my head
(and some in code) but I didn't want to make the code dependent on the
FFTW lib, and didn't have time to write a FFT myself at the time.

I will get some more time in a month. I could try to hack something
together then, if there is interest.


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