Conversions are always JPEG

[martijngastkemper]

Every conversion is formatted to JPEG. This is harde coded in Conversion.php. I'm wondering why this is hard coded and not possible to configure (I'm happy to create a PR to make the format configurable). It's convenient for most situations, but transparent PNGs and GIFs will "break".

It's possible to disable the behaviour, but this only works when you handle images. Creating a thumb for a PDF will result in a jpg saved as .pdf file.

$this->addMediaConversion('thumb')
    ->removeManipulation('format');

Because I can't find a discussion or documentation about this behaviour I was wondering if someone could explain me why this works as it works. Or point me to the information I'm missing, because I failed to find the documentation or failed to understand this feature.