using a source code debugger on vlc (and investigating a video performance problem)

[Shane Harper]

Hi.

I've been trying to use DDD v3.3 with GDB v5.0 to do source-level debugging
of vlc. I've had very little success.

I'd made the following changes to vlc/Makefile.opts:
- changed "OPTIMS = 1" to "OPTIMS = 0"
- changed "CFLAGS =" to "CFLAGS = -g"

At present when I try to start vlc from within DDD it runs for a short time
before GDB reports that the program exited normally. (No interface or video
output windows appear.)

If I try to attach the debugger to a running vlc process I also experience
problems, such as:
- breakpoints (sometimes) don't work.
- if I try to step through the code DDD can't show me the current line in
the code after a function call using a function pointer.

I would appreciate any suggestions on how to run a debugger on vlc.


The main problem I wish to investigate is why the XVideo (and X11) output
seems to become slower the longer they run. I've made the following
observations:
- after I've noticed that vlc is skipping a lot of frames if I pause the
video playback the video output thread can be using up to ~50% of my CPU
resources (should be 0% when playback is paused).
- changing to/from fullscreen mode seems to fix the problem (for a while).

Does anyone have any ideas?

(I'm running XFree86 v4.0.1a.)


Thanks,
Shane.