[FFmpeg-devel] regression - mpeg2 interlace/topfield flags not set anymore

Michael Niedermayer michaelni
Mon Jan 28 13:35:11 CET 2008

On Mon, Jan 28, 2008 at 12:07:53PM +0100, christophelorenz wrote:
> Rich Felker wrote:
> >On Mon, Jan 28, 2008 at 10:33:14AM +0100, christophelorenz wrote:
> >  
> >
> >>Rich Felker wrote:
> >>
> >>    
> >>
> >>>No, it breaks things on CORRECT platforms for the sake of working
> >>>
> >>>around a bug on BROKEN platforms. This is unacceptable.
> >>> 
> >>>
> >>>      
> >>>
> >>If tomorrow someone writes a piece of code that follows C99 standard and 
> >>works ok on xxx but fails under linux, what will happen ?
> >>After that will come C102, C150, C200 and all will be different again 
> >>and broken again.
> >>
> >>We live in a world full of unacceptable things (more important than a 
> >>computer standards), however if you want to move on, you have to make 
> >>compromises.
> >>
> >>I can hardly believe it is the first time ff contains a workaround for 
> >>some faulty implementation.
> >>Unless you're coding hello world, I can safely say that all libs on all 
> >>platforms are broken somewhere. Just that some are less than others....
> >>    
> >>
> >
> >Your rant is misplaced. I never in this thread said you can't work
> >around broken platforms, just that you cannot cause regressions on
> >valid platforms in the process. The traditional development model of
> >special-casing every known broken platform and failing to support a
> >not-already-known but fully-standards-conformant platform at all needs
> >to DIE.
> >
> >I still think this issue should be addressed with libbrokenos. But I
> >won't object to any workarounds that do not bloat or break working
> >systems. (Including our own implementation of strtod in ffmpeg would
> >be bloat; using strtol whenever "0x" is seen would be breaking
> >functionality, namely the ability to provide bit-exact floats.)
> >  
> >
> You're right. Sorry about this.
> And I will definitely report this problem to the mingw project.
> But the background problem stays...
> If we can't change the model because other than hex is unacceptable, if 
> we can't re-implement strtod, workaround the 0x interger parsing etc...
> I now wonder how we can get around this.

you can get around this by having av_get_string() return a series of
named flags like "trell+cbp+mv0", this also would be more readable
to humans than 0x00040201


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If a bugfix only changes things apparently unrelated to the bug with no
further explanation, that is a good sign that the bugfix is wrong.
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