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Opened 8 months ago

Last modified 7 months ago

#1713 new enhancement

black and white mode

Reported by: Antoine Martin Owned by: Antoine Martin
Priority: minor Milestone: future
Component: encodings Version: trunk
Keywords: Cc:

Description

We already have "png/L" support, but we could add a global black-and-white mode to try to save bandwidth:

  • jpeg supports TJPF_GRAY
  • all the video encoders would need a csc step
  • webp would need csc too

I'm not sure this will save enough bandwidth: the self-tuning video encode heuristics normally switch to YUV420P for video, and that already reduces the space taken by the colours to 33% or less of the bitstream.
For non-video, it may allow us to use a lossless encoding more often than we would otherwise.

Change History (1)

comment:1 Changed 7 months ago by Antoine Martin

Milestone: 2.3future

I don't see the point:

  • many things don't degrade well
  • none of the video encoders take grayscale as input
  • the cost of chroma is a small overhead (just a 33% with YUV420P - worst case scenario - often less if the video encoder interpolates chroma and luma)
  • the cost of a single lossless refresh dwarfs any savings we might have made at that point - best to make efficient use of the encodings we have than to invent new ones
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