Hello,

In order to update Exiv2, we need to know if this is okay to enable BMFF support. Patents have theoretically expired and it is enabled by default in the latest version.

https://bugzilla.redhat.com/show_bug.cgi?id=1979565

https://github.com/Exiv2/exiv2/issues/1679

Upstream seems to think it is okay because it is over 20 years old. Also other packages in Fedora are already using it, av1, jpeg-xl, any mp4 decoding.

By Jon Sneyers, one of the author of JPEG-XL:

I think this caution is erring on the side of paranoia, and possibly based on a misunderstanding.

ISOBMFF is pretty old, old enough for it to be impossible to still have applicable patents (patents expire after 20 years). It is a simple box-based container format that is used by many formats, including MP4, JPEG 2000, and JPEG XL.

One particular use of ISOBMFF is HEIF, which is more recent, and for which there actually are known patent claims by Nokia. HEIF does use the generic ISOBMFF box structure and extends it by defining mechanisms to do cropping, layering, grids, rotation etc, which are described in the HEIF spec. HEIF can be used with various payloads: when used with HEVC it is called HEIC, when used with AV1 it is called AVIF.

While most people would consider patents on a container format ridiculous, it is a fact that, at least in theory, if you use HEIF, you might risk patent litigation. Note that it would not be the application implementor who could be sued, but the end-user who uses the implementation and thereby possibly needs a patent license from Nokia.

This is only true specifically for HEIF though, not for ISOBMFF in general. Parsing the MP4 or JPEG 2000 container (which do not use HEIF) carries absolutely no risk in terms of patents, since they only use ISOBMFF, not HEIF. The same is true for JPEG XL, which has explicitly avoided using the HEIF container exactly for this reason.

TL;DR: ISOBMFF is OK, HEIF might be risky.

So just to be clear: reading BMFF is not an issue, it is over 20 years old so even if it was an issue in the past (it wasn't) it now certainly isn't anymore.

Reading HEIF-specific boxes is something else, but as long as Exiv2 is not doing that, there obviously is no issue either. Note that other FOSS tools like libheif and libavif actually do read those boxes, and they do seem to get away with it (but I can understand why you wouldn't want to do that; those boxes are from 2015 and Nokia does claim patents on them so it will only really be 'safe' to use that functionality in 2035).

So while I appreciate the caution, I think it's OK to just enable the BMFF code by default (perhaps have an option to disable it, if someone is still for some reason worried, but imo that would be an unfounded worry). Otherwise most of the modern image codecs (jp2, jxl, avif and heic) end up being unsupported by default, for no good reason, which seems a suboptimal situation.

Could we come to a resolution of that situation quickly?

Thank you,

Have a great sunday.

Robert-André