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IDProjectCategoryView StatusDate SubmittedLast Update
0000590DCP-o-maticBugspublic2015-06-09 14:322015-09-01 23:40
Reportercarl Assigned To 
PrioritynormalSeverityminorReproducibilityhave not tried
Status acknowledgedResolutionopen 
Summary0000590: Strange aliasing / quantisation with Prores 4444 source
Description

I’ve done a bit more testing and can confirm that there’s definitely a bug somewhere with how DCP-o-matic is translating color.

I did a test with DCP-o-matic, OpenDCP and EasyDCPCreator+

I used the ProRes4444 test source for DCP-o-matic and and EasyDCPCreator (FARM_DCP_test.mov)

Here’s a screen grab of the same frame from both packages (attached)

Note the heavy aliasing of the text in the DCP-o-matic output.

I repeated the test with the same test source converted into a .TIFF sequence and got the same results comparing the output of DCP-o-matic with OpenDCP — OpenDCP has clean text output, while DCP-o-matic’s output has the same aliased text.

I imagine whatever problem is causing this text aliasing is probably what caused the banding I saw in my first DCP.

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carl

2015-06-09 14:32

administrator  

Screen_Shot_2015-06-08_at_3.09.54_PM.png (1,161,577 bytes)

carl

2015-06-09 14:33

administrator  

Screen_Shot_2015-06-08_at_3.11.01_PM.png (1,179,249 bytes)

carl

2015-06-14 23:49

administrator   ~0000680

TIFF -> DCP being wrong with DOM means that it's either the TIFF decoding or the J2K encoding.

Strangely, converting the .mov to TIFFs with FFmpeg, the TIFFs and the J2K output from DOM look the same.

Could be the sRGB / Rec 709 conversion..?

carl

2015-06-15 01:21

administrator   ~0000683

Last edited: 2015-06-15 01:23

Looks like a problem with the MOV decoding. Comparing an FFmpeg-created TIFF with one provided by dhl looks like the horizontal resolution is halved with the FFmpeg one, or something weird is going on and it's blurring pixels horizontally. I guess the same strange thing is then going on when dhl imports TIFFs into DOM...?

carl

2015-06-15 01:23

administrator  

good_tiff_zoomed.png (46,324 bytes)   
good_tiff_zoomed.png (46,324 bytes)   

carl

2015-06-15 01:23

administrator  

bad_tiff_zoomed.png (44,805 bytes)   
bad_tiff_zoomed.png (44,805 bytes)   

carl

2015-06-16 10:02

administrator   ~0000691

Probably should export a TIFF from that MOV file using Final Cut or something and compare it to the FFmpeg one.

carl

2015-07-07 00:00

administrator   ~0000739

Final Cut / FFmpeg comparison is similar; almost but not quite halved resolution. Marked as yuva444p10le so you'd think it wasn't a chroma subsampling thing.

Bug History

Date Modified Username Field Change
2015-06-09 14:32 carl New Bug
2015-06-09 14:32 carl File Added: Screen_Shot_2015-06-08_at_3.09.54_PM.png
2015-06-09 14:33 carl File Added: Screen_Shot_2015-06-08_at_3.11.01_PM.png
2015-06-14 23:49 carl Note Added: 0000680
2015-06-15 01:21 carl Note Added: 0000683
2015-06-15 01:23 carl File Added: good_tiff_zoomed.png
2015-06-15 01:23 carl File Added: bad_tiff_zoomed.png
2015-06-15 01:23 carl Note Edited: 0000683
2015-06-16 10:02 carl Note Added: 0000691
2015-07-07 00:00 carl Note Added: 0000739
2015-07-08 14:16 carl Target Version => 1.x
2015-08-28 23:20 carl Target Version 1.x => 2.x
2015-09-01 23:40 carl Status new => acknowledged