[FFmpeg-user] Problems with opening some DPX files

[AB_ffmpeg]

On 19-03-15 13:47, Christoph Gerstbauer wrote:
> Hello,
>
> I am testing the transcoding of different DPX files from different 
> sources.
>
> I have here 2 files which cannot be opened by ffmpeg.
>
> https://dl.dropboxusercontent.com/u/26129407/ProblematicDPX_1.zip
>
> When I open the files with ImageMagick and GraphicsMagick they look 
> distorted (can be seen in the png from the zip file).
> Opening the files with Photoshop they look also very weird but 
> different to GM and IM. (see PNGs in zip)
>
> Any ideas whats going on here?
>
> Best Regards
> Christoph
>
>
> COMMAND LINE OUTPUT:
>
> C:\Users\gersti>ffmpegnew -i "I:\DPX\_DPX examples\Bojan\0090000.dpx"
>
...
> [dpx @ 0000000002cf7c40] Packing 2 is not implemented. Update your 
> FFmpeg version to the newest one from Git. If the problem still 
> occurs, it means that your file has a feature which has not been impl
>


Hi Christoph,

after a little search these are my findings

ffmpeg throws a packing error at you" "Packing 2 is not implemented"
According to the DPX v2 specs packing 2 is 8 bit values:

The origin of your DPXs as stated in the header is a Scanity, which can
do 8 bits scans. This might be the origin of the issue.
http://www.dft-film.com/downloads/datasheets/Scanity-HDR.pdf

8 Bit data values are not supported in ffmpeg (and not very well supported
in any program as far as I know):
https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/dpx.c
lines 141-144

Here's a bit more info about 8 bit image data issues in the DPX specs:
http://www.simplesystems.org/users/bfriesen/dpx/dpx-issues.pdf

I see a black and white image in Nuke which sort of confirms the storage
of RGB channels in one value.

The skew in the image is probably caused by a mismatch in image width
and pixel aspect ration (which says it's 2048x2048)

gr
Arno