We no longer need to get pools from the display module. We only have 2 separate pools for the converter and for the filters+blender.
We also don't need to create the converter pool if we know there will be no converter.
This will reduce the amount of memory allocated during playback, especially when there is a converter (20 pictures forced so far).
Tested with and without a converter with multiple filters/blending.
Draft on top of !3987 (merged)
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