[FFmpeg-devel] [PATCH v2 0/3] Make fate tests succeed with zlib-ng

[Alexander Strasser]

On 2024-12-14 11:09 +0100, Anton Khirnov wrote:
> Quoting Alexander Strasser via ffmpeg-devel (2024-12-01 21:13:56)
> > This is a fixed up version of the series I sent before.
> >
> > This worked for me on Ubuntu 20.04 but probably will break
> > with older zlib versions as Hendrik pointed out in the
> > previous thread. Either we must update zlib on affected
> > FATE clients or add more .alt files to them as well.
> >
> > We could also go the further the "no_file_checksums" as
> > was demonstrated by James' series.
> >
> > I still prefer this way because it's simpler and retains
> > the value of the tests.
>
> This seems like a hack to me.

Depends on what you precisely mean by hack.
It is a way to accommodate for shortcomings in older, but
still widely used zlib versions.


> We should not be testing for bitexact output from code that is not under
> our control and does not guarantee bitexactness.

Ideally!

OTOH we also indirectly test that other code like C std lib functions
work as expected.

In this case short of bugs in zlib/zlib-ng I do not see why the output
should differ with compression level 0. Maybe I'm missing something
I didn't look that deep into how zlib exactly works.


  Alexander