[FFmpeg-devel] Assert failing in libavcodec - ratecontrol.c

[Neil Brown]

On Saturday August 4, michaelni at gmx.at wrote:
> Hi
> 
> On Wed, Jul 25, 2007 at 06:25:58AM +1000, Neil Brown wrote:
> > On Sunday July 15, wzrlpy at arsystel.com wrote:
> > > >>
> > > >> is this reproduceable with command line ffmpeg? if yes please provide
> > > >> full uncut output and command line parameters
> > > >
> > > > I was hoping someone would know what those asserts really meant and we
> > > > could work backward from there.....
> > > > But I can try working forward.  It would probably be easiest if I
> > > > could feed a number of images (e.g. jpegs) into ffmpeg for it to
> > > > encode into an mpeg.  I couldn't see anything obvious in the man page
> > > > which would allow this.  Is there a way to do that?
> > > 
> > > Yes: second entry in FAQ. (http://ffmpeg.mplayerhq.hu/faq.html)
> > 
> > Thanks.
> > 
> > Ok, here is the command line:
> > 
> >  ffmpeg -i tmp/%d.jpg -i_qfactor 1.25 -i_qoffset -0.8 -b 20000000 /tmp/xxx.mpeg
> > 
> > where 'tmp' is a directory containing 500 file, the first 250 all the
> > same, and the next 250 also all the same, but different to the first
> > 250. All files 720x576.
> > 
> > I tried reducing the input set, and with 12 of one image and 1 of the
> > other, it will 
> > ffmpeg: ratecontrol.c:756: ff_rate_estimate_qscale: Assertion `q>0.0' failed.
> 
> this should be fixed
> 

Awesome - thanks!

I actually convinced the MLT developers to switch to the same defaults
as ffmpeg uses, which is probably a sensible thing to do anyway.  But
this now means we have two lines of defence against that crash :-)

Thanks,
NeilBrown