[FFmpeg-devel] [PATCH] snow: remove strange av_assert2

Michael Niedermayer michaelni at gmx.at
Wed Jul 8 18:07:38 CEST 2015


On Wed, Jul 08, 2015 at 07:24:13AM -0400, Ronald S. Bultje wrote:
> Hi,
> 
> On Tue, Jul 7, 2015 at 7:22 PM, Michael Niedermayer <michaelni at gmx.at>
> wrote:
> 
> > On Tue, Jul 07, 2015 at 11:32:59PM +0200, Andreas Cadhalpun wrote:
> > > On 06.07.2015 02:40, Michael Niedermayer wrote:
> > > > On Sun, Jul 05, 2015 at 09:11:44PM +0200, Andreas Cadhalpun wrote:
> > > >> Can you explain how elements can be too larger to fit?
> > > >
> > > > emulated_edge_mc() writes a block of width x height,
> > >
> > > More precisely that's block_w x block_h.
> > >
> >
> > > > if stride < width this will not work as intended
> > >
> > > Then an assert for stride > block_w might make sense in emulated_edge_mc,
> > > but not in add_yblock.
> >
> > ok, added
> 
> 
> I don't think this makes sense:
> - first of all, it should be >=;

that is what i added, i had just forgot mentioning that in my reply


> - second of all, are we going to add asserts to each and every function
> that takes a stride argument?

> - third of all, if people want to call if with stride = 0 or negative
> stride or whatever, why not? The function still does what it does, just
> overwrites its own data. Not our problem.

my commit already handled negative strides.


> - last of all, I want to remind you guys that we haven't done a very
> thorough code analysis to see if this can actually be triggered. As an
> example, look at commit 458446acfa1441d283dacf9e6e545beb083b8bb0. Before
> that, vp8 files smaller than 16x16 or vp9 files smaller than 64x64 could
> cause aborts. The vp9 ones I noticed due to some fate files being so small.
> I doubt you'll ever find such vp8 files, but they're valid.
> 
> Let's not add silly checks to replace other silly ones.

if people prefer i ca revert b8c438e7623644edcfdb508c946a723a3b79b893
or add a check for stride == 0

what do people prefer ?

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The bravest are surely those who have the clearest vision
of what is before them, glory and danger alike, and yet
notwithstanding go out to meet it. -- Thucydides
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