Maximizing Video Quality when Decrypting and Exporting Encrypted DCP to MP4 using dcpomatic2_create and dcpomatic2_cli

[lijun]

Hello

I am currently working on a project where I need to decrypt an encrypted Digital Cinema Package (DCP) and export it as an MP4/MOV video file. I am aiming to preserve the highest possible video quality during this process. To achieve this, I am using the following commands in sequence:

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dcpomatic2_create -o outputdir --kdm KDM_Testenc1_FTR-1_F-178_XX-XX_51_2K_20231118_SMPTE_OV_cinema_projector1.xml Testenc1_FTR-1_F-178_XX-XX_51_2K_20231118_SMPTE_OV

dcpomatic2_cli --export-format mp4 --export-filename filename.mp4 outputdir

My primary concern is whether this approach will allow me to retain the highest quality of the original video content. I am aware that DCPs generally have high bitrates and specific color space settings, and I want to ensure that these qualities are not significantly compromised in the MP4 output.

Could you please advise on the following points:

Quality Retention: Are there specific parameters or additional steps I should consider to maximize the quality retention during the export process?

Advanced Settings: Is there a way to adjust advanced settings like bitrate, color space, or frame rate in the dcpomatic2_cli command to closely match the original DCP's specifications?

Alternative Methods: If the current method I'm using is not ideal for quality preservation, could you suggest any alternative approaches or tools within the DCP-o-matic suite that might be better suited for this purpose?

Any insights or recommendations would be greatly appreciated, as maintaining the integrity of the video quality is crucial for my project.

[carl]

Do you specifically need a MP4/MOV? If you really want to preserve everything, I guess the best thing would be just to make an unencrypted DCP.

[lijun]

how to make an unencrypted DCP by command line?

[carl]

I didn't test this but something along the lines of

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dcpomatic2_create -c FTR --container-ratio 185 -o decrypt --kdm my_kdm.xml my_unencrypted_dcp
dcpomatic2_cli decrypt

should do it. Unfortunately I think you need to specify the correct container ratio. Ideally there would be an option to take the project settings from the DCP (like there is in the GUI).

[lijun]

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dcpomatic2_create --no-encrypt  -o outputdir3noencdcp  --kdm KDM_Testenc1_FTR-1_F-178_XX-XX_51_2K_20231118_SMPTE_OV_cinema_projector1.xml Testenc1_FTR-1_F-178_XX-XX_51_2K_20231118_SMPTE_OV

dcpomatic2_cli  outputdir3noencdcp

it works.