[FFmpeg-devel] [PATCH] avcodec: Switch bitrate to 64bit with the bump

[wm4]

On Wed, 2 Sep 2015 14:06:43 -0700
Ganesh Ajjanagadde <gajjanag at mit.edu> wrote:

> On Wed, Sep 2, 2015 at 1:57 PM, wm4 <nfxjfg at googlemail.com> wrote:
> > On Wed, 2 Sep 2015 16:49:41 -0400
> > "Ronald S. Bultje" <rsbultje at gmail.com> wrote:
> >
> >> Hi,
> >>
> >> On Wed, Sep 2, 2015 at 4:47 PM, Ganesh Ajjanagadde <gajjanag at mit.edu> wrote:
> >>
> >> > On Wed, Sep 2, 2015 at 1:20 PM, Michael Niedermayer <michaelni at gmx.at>
> >> > wrote:
> >> > > From: Michael Niedermayer <michael at niedermayer.cc>
> >> > >
> >> > > a 32bit bitrate is insufficient for high resolution, high framerate
> >> > material
> >> > > an example would be rawvideo
> >> > >
> >> > > Not all changes are covered by #if as its easier to just push when the
> >> > > bump is done instead of making it coditional and removig the
> >> > conditionallity
> >> > >  again
> >> >
> >> > Not for this patch; but just a thought - I noticed in swresample the
> >> > use of int for sample rate. Note that all the C spec guarantees is int
> >> > >= 16 bits, and 2^15 < 33000 which is insufficient for a lot of audio.
> >> > Your comment above seems to reflect the assumption that int >= 32
> >> > bits. Maybe this assumption is made elsewhere in the codebase as well,
> >> > but it is not safe as per the standard. Thus, I feel swresample rate
> >> > should be an int32_t; and there may be more opportunities for cleanup
> >> > elsewhere.
> >>
> >>
> >> FFmpeg assumes int >= 32bit. We don't support platforms where this
> >> assumption doesn't hold.
> >
> > While this is true, it would actually be an advantage if some of ints
> > all over the codebase changed to size_t. For example, FFmpeg can't
> > process images over 16000x16000 in size, which is just ridiculous,
> > because there are many real-world cases which need resolutions this
> > high (consider scans etc.).
> 
> Thanks all for clarifications. I assume environments where int=16 bit
> are quite rare. However, as a long term goal, could there be some
> potential users (e.g embedded guys) who would benefit from relaxing
> the int>=32 bit assumption?

Just no. Show me a meaningful embedded 16 bit platform that can make
meaningful use of libavcodec. Even _if_ a 16 bit embedded thing would
play media, it'd use its own dedicated circuity instead of doing it on
a general purpose CPU.

Another angle: as long as you can't show me an architecture that would
actually benefit from such a relaxation _and_ be worth all the effort
for it, nobody is going to be interested. (And in fact, should not
waste his time on such theoretical things.)