[Libav-user] Help using libavfilter: filters aren't being applied

Leandro Santiago leandrosansilva at gmail.com
Thu Jun 14 14:46:58 CEST 2012

Hello to all. I'm trying to use libavfilter and initially I created a
simple .c file which reads a frame from a input and convert this frame
to an output png image.

I tried to follow the file doc/examples/filtering_video.c and right
now my program just open a file, get a frame and save it in a PNG. I'm
trying to convert pixel format with format filter (but it's not

I'm also trying do draw a box in the image, but it seems my filter
aren't being applied (although the log says they're being created).

The complete source code is in: http://pastebin.com/9cjLnXZ6

Can you tell me what I'm doing wrong?

The usage is:
./executable input.avi avi # (where avi is the input type)

It will create a file called test.png in the current directory.

Sent from my Atari

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