[Interest] libjpeg vs. libjpeg-turbo/mozjpeg

[Allan Sandfeld Jensen]

On Saturday 23 May 2015, René J.V. Bertin wrote:
> On Saturday May 23 2015 11:20:20 Allan Sandfeld Jensen wrote:
> > On some Linux distros libjpeg-turbo is installed as the default libjpeg,
> > and Qt automatically links to that. I have not heard of any issues with
> > that.
> 
> Yes, this I know, it's apparently the case with most distros. What is much
> harder to assess is
> 
> - how about non-x86 architectures (PPC in casu)?
Look in libjpeg-turbo. Their optimizations are architecture specific, so I 
doubt they have anything for it, but I don't know.  I know when Firefox 
discussed adopting it they didn't even have NEON optimizations yet, but said 
they would work on it.

> - how about the additional features in the current libjpeg (9) and/or
> features that might be planned for inclusion in the next version. Are
> those used or likely to be used at some point in Qt? - would it be in any
> way disruptive for your build/distribution system if the jpeg libraries in
> MacPorts are downgraded to the v8 ABI?
We don't rely on them as far as I know, but the new compression formats might 
be supported automatically by libjpeg and thus by Qt linked against libjpeg-
v9, but if no one are using them because they are non standard, losing them 
shouldn't be a problem.

The bug for replacing lbjpeg with libjpeg-turbo is 
https://bugreports.qt.io/browse/QTBUG-40091 - Feel free to take it over :)

Regards
`Allan