[MPlayer-users] BUG: mencoder segvault with -vf pullup [partial bugreport]

[D Richard Felker III]

On Sat, Sep 13, 2003 at 11:08:25AM -0700, Corey Hickey wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]

> Hi,
> 
> I just ran into a segfault with mencoder and -vf pullup. It seems that
> pullup is unhappy when I crop the movie, but has no trouble when I
> don't.
> 
> [WORKS]
> mencoder pullup-segfault.vob -vf crop=716:374:2:48 -ovc lavc\
>  -lavcopts vcodec=mpeg4 -oac copy
> 
> [ALSO WORKS]
> mencoder pullup-segfault.vob -vf pullup -ovc lavc\
>  -lavcopts vcodec=mpeg4 -oac copy
> 
> [DOES NOT WORK]
> mencoder pullup-segfault.vob -vf crop=716:374:2:48,pullup -ovc lavc\
>  -lavcopts vcodec=mpeg4 -oac copy
> 
> For this last case, I've attached the verbose output of mencoder.
> 
> The segfault happens right at the beginning, so I've dd-ed the first
> 100k, and uploaded that to ftp.mplayerhq.hu as pullup-segfault.vob.
> That file is also publicly available at:
> http://bugfood.casa-z.org/mpbug/pullup/pullup-segfault.vob
> 
> In case you want a larger piece of the file, I've made a 50MB chunk
> at:
> http://bugfood.casa-z.org/mpbug/pullup/pullup-segfault-larger.vob
> 
> Rich, is this enough information for you? I can do a full gdb bugreport
> if you want, but I'm too lazy to do so unless you tell me you need it.
> :)

The problem is your crop parameters -- they don't make sense. Granted,
it shouldn't segfault, but it's impossible to inverse telecine 716x374
video since height isn't a multiple of 4. (Chroma plane is half
sampled = 358x187, whereas with interlaced video you must have 2
fields and this even height.) If you're going to crop before passing
input to pullup, both height and y-offset must be multiples of 4.

I would recommend just overcropping a little (crop=716:372:4:48, or
better yet crop=704:372:10:48), but if you insist on exact cropping,
you can wait to do the crop til after inverse-telecine.


Rich