[FFmpeg-devel] [GSoC] Qualification Task

Mina Nagy Zaki mnzaki at gmail.com
Tue Mar 22 08:54:02 CET 2011

I've ported a small filter from sox, the 'earwax' filter, essentially a stereo 
widening effect. It's a relatively simple filter, I was actually looking to 
write a general sox wrapper but turns out there would be a few things that 
would make this slightly difficult.

The attached patch is against the audio-filters branch from sastes-ffmpeg repo.
For reference, the SoX effect code: 

I've actually changed the main loop ('flow' function in earwax.c) to avoid what 
looks like a bug in the sox implementation (although it could turn out to be a 
trick to add delay, but the delay would be dependent on buffer size :S). The 
output seems pretty similar to my ears though.
It's not a very good effect BTW :D

I've come across a bug in graph string parsing, when there's only one filter 
and you use a semicolon like -af "widen;" it works without the semicolon 

The segfaults mentioned on IRC were actually because I was clearing out of 
bounds memory and overwriting open_inputs and open_outputs in 
configure_audio_filters, so a bunch of string utils where segfaulting on the 
NULL names and whatnot :D my bad.

Mina Nagy Zaki

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