[FFmpeg-devel] [PATCH] avformat/mxfdec: only check index_edit_rate when calculating the index tables

[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.

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. In this case, I could only craft an MXF 
file, because I don't have access to the software.

Regards,
Marton