Learning about Dolby Vision and CoreELEC development

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Minor update from the -ng version in Learning about Dolby Vision and CoreELEC development - #341 by doppingkoala. See that post for setup + known issues.

Change:
Added automatic adjustment of L1 metadata. The value of the L1 min_pq is clipped to be at least the value of source_min_pq. The value of the L1 max_pq is clipped to be at most the value of source_max_pq. This matches what was observed in the hdmi tunnel captures.

Can disable this with

echo N > /sys/module/amvideo/parameters/L1_adjust

Re-enable with

echo Y > /sys/module/amvideo/parameters/L1_adjust

These can be changed while playing a file and have immediate affect.

With this change, the only differences between the DV output of this build and an official device I’m aware of are:

  • This build will output a L5 crop. This resolves issues with positive lift values. See test files in @R3S3T_9999 Offset positive Lift Test folder for examples.
  • The video signal remains in YCbCr format. This differs from devices that use a dovi.ko that unnecessarily do a color space conversion.

For anyone that tests, please report any other differences in the displayed images output from this build and an official DV device for any content that is playable as p8.1.

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