On Fri, 3 May 2024, Tomas Härdin wrote:
tor 2024-05-02 klockan 23:01 +0200 skrev Marton Balint:
On Mon, 29 Apr 2024, Tomas Härdin wrote:
> mån 2024-04-15 klockan 21:34 +0200 skrev Marton Balint:
> > Commit ed49391961999f028e0bc55767d0eef6eeb15e49 started rejecting
> > negative
> > index segment edit rates to avoid negative av_rescale parameters.
> > There are two
> > problems with this:
> >
> > 1) there is already a validation for zero (uninitialized) rates
> > later
> > on
> > 2) it rejects files with 0/0 index edit rates which do exist and
> > we
> > should
> > continue to support those
>
> There are no such files in FATE last time I checked. At the very
> least
> we need to know which vendor is producing such broken files.
>
> Without tests covering the workflows we want to support, we have no
> confidence in refactoriing. This leads to cargo culting. And to be
> sure, every workflow we support means a non-trivial amount of work,
> especially when it comes to MXF.
I can add a comment to the code or the commit message, we did this
plenty
of times in the past. The broken software is Marquise Technologies MT
Mediabase 4.7.2 by the way. I can also rework the patch to keep
rejecting
negative values and only allow zero, as that is the only thing I
*know* to
exist.
We could also tell Marquise Technologies to fix their software. MXF is
a living ecosystem
If we add a new FATE file for every fixed file or workflow, the
amount of
FATE samples (and the time fate will run) will increase
significantly, I
am not sure that is intended.
"Support any old workflow but don't add tests for them" is a ridiculous
position. It also prevents refactoring. There are real costs to
supporting workflows that no one uses. Hence why I mention SLAs. The
only people interested in MXF are professionals.
And what if a home user gets a file from a professional user? Crippling
professional use cases from ffmpeg, or make professional features a
payable option - via SLA or otherwise - is something I cannot support.
In this case, I could only craft an MXF
file, because I don't have access to the software.
Yes we can craft arbitrarily broken files. That doesn't help anyone.
It's just cargo culting.
Cargo culting would be fixing files which do not exists in the wild.
Files with 0/0 index edit rate do exist. So this patch clearly helps
anybody who is trying to play those.
I can create a fate test for supporting 0/0 index edit rates if that is
indeed preferred.
Regards,
Marton
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