[FFmpeg-devel] [PATCH 2/2] qt-faststart - optimize the offset change loop

[Eran Kornblau]

> On Wed, May 30, 2018 at 05:39:50AM +0000, Eran Kornblau wrote:
> > > 
> > > 
> > > -----Original Message-----
> > > From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On 
> > > Behalf Of Michael Niedermayer
> > > Sent: Wednesday, May 30, 2018 12:37 AM
> > > To: FFmpeg development discussions and patches 
> > > <ffmpeg-devel at ffmpeg.org>
> > > Subject: Re: [FFmpeg-devel] [PATCH 2/2] qt-faststart - optimize the 
> > > offset change loop
> > > 
> > > > +                *ptr++ = (current_offset >> 56) & 0xFF;
> > > > +                *ptr++ = (current_offset >> 48) & 0xFF;
> > > > +                *ptr++ = (current_offset >> 40) & 0xFF;
> > > > +                *ptr++ = (current_offset >> 32) & 0xFF;
> > > > +                *ptr++ = (current_offset >> 24) & 0xFF;
> > > > +                *ptr++ = (current_offset >> 16) & 0xFF;
> > > > +                *ptr++ = (current_offset >>  8) & 0xFF;
> > > > +                *ptr++ = (current_offset >>  0) & 0xFF;
> > > 
> > > can this be simplfified with
> > > libavcodec/bytestream.h, libavutil/intreadwrite.h or similar ?
> > > 
> > > [...]
> > > 
> > 
> > Yes, I can change it to AV_WB32/AV_WB64, but at the moment this 
> > utility is completely stand-alone - it does not depend on anything from ffmpeg, so maybe it's better to keep it this way.
> 
> well, i surely wont insist but these should not add dependancies just use inline functions and macros from headers I think it does no harm to use these as it doesnt add a depency at link
> 
Right, but it does add a dependency on configure, since intreadwrite.h includes libavutil/avconfig.h.
I don't think it's too important, but currently I can pull only qt-faststart.c and run: gcc qt-faststart.c -o qt-faststart, which can be convenient.
Anyway, let's table this patch, as I've just completed the larger patch for the issue I originally encountered (stco offset overflow).
In the larger patch I locally defined AV_WB32/64, as I had to do this in multiple places.

Thanks

Eran

> 
> [...]
> -- 
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> 
> Awnsering whenever a program halts or runs forever is On a turing machine, in general impossible (turings halting problem).
> On any real computer, always possible as a real computer has a finite number of states N, and will either halt in less than N cycles or never halt.
>