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

Ronald S. Bultje rsbultje at gmail.com
Wed Sep 2 23:11:11 CEST 2015


Hi Ganesh,

On Wed, Sep 2, 2015 at 5:06 PM, 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?


It's a little bit theoretical. Maybe we should address that once we have a
clear use case.

Ronald


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