[FFmpeg-devel] debuggin ffmpeg

Wolfgang Haupt w.haupt at at-visions.com
Tue Feb 18 14:05:57 CET 2014

On 02/18/2014 01:37 PM, Maxim Polijakowski wrote:
> Am 18.02.2014 11:41, schrieb Wolfgang Haupt:
>> Hi ffmpeg-devs,
>> I'm quite new to ffmpeg just trying to figure out how the mpegts 
>> demuxer works in detail.
>> Therefore I started debugging into ffprobe (-show_frames).
>> However I wonder how you guys do debugging because every second 
>> variable is optimized out.
>> I guess optimizing is rather important in ffmpeg, so I'd like to ask 
>> if it's safe to disable optimizing for debug builds?
> I debug the ffmpeg executable quite often. Below the description of 
> how I do that:
> 1) obtain the debug build by running
> cd [path/to/your/ffmpeg/local/clone]
> ./configure --enable-debug=3 --disable-optimizations --disable-inline-asm
> make
> 2) fire up GDB and type in the following commands:
> gdb [path/to/ffmpeg/executable]
> set args -i [path/to/input/file] test.avi [or some other output file 
> or null]
> break libavformat/mpegts.c:135 [or some other line]
> run
> Surely, you can do the same with ffprobe and use another debugger...
> Best regards
> Maxim
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Thx all for your hints, I use gdb in exact the way you stated.
It's just the configure parameters I wasn't sure about, because I once 
tried debugging on an ARM device with compiled NEON and a dev told me to 
better not disable optimizations there.
I guess ARM NEON is a very special case and I'm working on x64_64 right now.
That's basically why I wanted to ask here, how ffmpeg devs do debugging.
Referring to your feedback I guess it's OK when working on my PC.

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