[FFmpeg-devel] [PATCH] avcodec/tiff: Add support for recognizing DNG files

[Lauri Kasanen]

On Mon, 18 Mar 2019 09:13:01 +0100
Moritz Barsnick <barsnick at gmx.net> wrote:

> On Sun, Mar 17, 2019 at 23:05:01 +0100, Paul B Mahol wrote:
> > Still wrong, You can decode images you linked just fine (albeit with
> > incorrect colors) with command:
> > 
> > ffmpeg -subimage 1 -i IMAGE.dng ....rest of command.
> 
> Shouldn't, ideally, these image files be demuxed as two image streams?
> Perhaps with the "main" image as the first stream.

The DNG spec is pretty massive, and there's a huge amount of
variations. There can easily be far more than two streams, there could
be several "main" images and several previews in different sizes. Their
order can vary too, it's not always the thumbnail first; thumbnails can
also be omitted entirely. There's also several different
encodings/compression types for the "main" images.

I've used their libdng for a project. It's a big LGPL library
implementing pretty much everything, but no distro really ships it, so
it'd have to be embedded or built manually by the user.

- Lauri