[Interest] libjpeg vs. libjpeg-turbo/mozjpeg

[Konstantin Tokarev]

26.05.2015, 18:47, "Matthew Woehlke" <mw_triad at users.sourceforge.net>:
> On 2015-05-23 13:50, René J.V. Bertin wrote:
>>  On Saturday May 23 2015 19:06:47 Allan Sandfeld Jensen wrote:
>>>  The bug for replacing lbjpeg with libjpeg-turbo is
>>>  https://bugreports.qt.io/browse/QTBUG-40091 - Feel free to take it over :)
>>  Funny how that focuses on a performance difference which is
>>  apparently not due to using libjpeg-turbo vs. the regular version.
>
> Hmm...
>
> Performance is *exactly* why we switched to building our own
> libjpeg-turbo and then building Qt against that, rather than using the
> bundled libjpeg.
>
> We have an application that deals with what is effectively MJPEG video,
> but we are handling the "M" part of it ourselves, and using Qt to read
> and write frames. We ran into problems with HD video; it worked fine on
> Linux, but had serious issues on Windows. After tracking it down to the
> time spent reading/writing the frames, we realized that on Windows, Qt
> was using a bundled libjpeg, while Linux of course was using
> libjpeg-turbo. Building Qt on Windows against an externally built
> libjpeg-turbo fixed the problem.

FWIW, MJPEG is by far not the best codec choice for HD video.

-- 
Regards,
Konstantin