Packing DCP from conformed j2c image sequence

[ceeller]

Hello everyone. I'll preface this by stating that I searched for "j2c" and didn't turn up any threads with that keyword.

When packing a DCP and sourcing the picture from already prepared j2c image files it looks like DCP-o-matic is re-processing the frames rather than just copying them over into the picture MXF. Is this the expected behavior or is there a switch that I've missed to bypass re-processing?

Thank you,
Chris

[carl]

It shouldn't be reprocessing them, unless you have changed things like crop, letterboxing etc. etc. Are your J2C files the same pixel size as your DCP's container?

[ceeller]

Hi Carl,

Thanks for the confirmation, which leads me to operator error. The picture conforms to container size. What I did do, out of habit, was to select color space conversion, which is unneeded since the j2c files are already in X'Y'Z' color. I'll be sure to triple check the package settings when I start it again here in a minute.

On a side note, thank you for maintaining this project. At work I use Freunhofer EasyDCP Creator+ and it's pretty nice, but for unusual projects or for my home projects having the option of DCP-o-matic is very helpful.

Thank you,
Chris

[carl]

Thanks for the confirmation, which leads me to operator error. The picture conforms to container size. What I did do, out of habit, was to select color space conversion, which is unneeded since the j2c files are already in X'Y'Z' color. I'll be sure to triple check the package settings when I start it again here in a minute.

That would do it, I think: choose "None" and it should pass the data through. There should probably be a clear statement in the UI of what DCP-o-matic is going to do with the J2K data.

On a side note, thank you for maintaining this project. At work I use Freunhofer EasyDCP Creator+ and it's pretty nice, but for unusual projects or for my home projects having the option of DCP-o-matic is very helpful.

Cool Feel free to make feature requests for the things that EasyDCP Creator does better!

[ceeller]

On a side note, thank you for maintaining this project. At work I use Freunhofer EasyDCP Creator+ and it's pretty nice, but for unusual projects or for my home projects having the option of DCP-o-matic is very helpful.

Cool Feel free to make feature requests for the things that EasyDCP Creator does better!

At the moment the only feature that EasyDCP Creator+ has is speed. My workstation packs DCPs with picture transcoding at about 12-14 frames per second. DCP-o-matic works about 6 fps on the same system. The code for EasyDCP's j2c transcoder is multithreaded and fast.

Thanks.

[carl]

Fair enough; there are plans to fix that, but it's not especially easy. DCP-o-matic is multihreaded, but still slow

[Carsten]

Chris - how did you create the j2c?

Keep in mind that j2c does not guarantee DCI compliance. Thus, J2C may have the wrong color space, gamma, and data rate constraints. DCP-o-matic will wrap them into a formally correct DCP, but they may crash some or all playback servers. We had that in the past with j2c created with Resolve, when users thought that the only intended use for J2C or JPEG2000 could be a DCP and thus assumed all J2C parameters set by Resolve were compliant with DCI.


- Carsten

[ceeller]

Chris - how did you create the j2c?

Keep in mind that j2c does not guarantee DCI compliance. Thus, J2C may have the wrong color space, gamma, and data rate constraints. DCP-o-matic will wrap them into a formally correct DCP, but they may crash some or all playback servers. We had that in the past with j2c created with Resolve, when users thought that the only intended use for J2C or JPEG2000 could be a DCP and thus assumed all J2C parameters set by Resolve were compliant with DCI.

- Carsten

Hi Carsten,

In the case of my example the j2c frames were generated by the Fraunhofer standalone transcoder so I'm confidant that they conform to spec since that transcoder is programmed with DCI spec in mind.

[Carsten]

Alright, those j2c should indeed form a DCI compliant stream.

- Carsten