mpv-player / mpv-player/mpv

Subtitle antialiasing (or independent scaling)

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#2,820 5 comments 1 reaction 0 assignees View on GitHub

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core:subtitle filter meta:feature-request priority:low
Dominant language
C
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Description

Aliasing in ASS subtitles can be "solved" with blend-subtitles=video:scale=ewa_lanczossharp:scale-blur=1.5:dscale=bicubic/mitchell, but this also applies blur to whole image, causing loss of detail.

It would be great to have the option to apply blur only to the ASS subtitles or use different upscaling/downscaling methods for the subs (independently from the video scalers).

Some ideas:

#Independent subtitle scaling
scale=ewa_lanczossharp:ass-scale=bicubic
dscale=anysharpdownscaler:ass-dscale=mitchell
#Blur/antialiasing
scale=ewa_lanczossharp:scale-blur=1.15:ass-scale=ewa_lanczos:ass-scale-blur=1.6
scale=ewa_lanczossharp:dscale=mitchell:ass-aa=yes
#AA/blur when not scaling
wns-ass-blur=1.12
wns-ass-aa=yes
ass-scale=bicubic:ass-dscale=mitchell:wns-ass-blur=1.12
#drawing subtitles to window resolution and then apply a soft downscaling to video resolution
ass-autoscaling #not supposed to work with _blend-subtitles=video_
ass-autoscaling:wns-ass-aa=yes

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

No files, tests, or entry points are identified in the issue. Start by locating mpv's ASS subtitle rendering and video scaling paths, then define and test a focused design that applies subtitle antialiasing or independent scaling without blurring the video.

Written by the indexing model from the issue text.

Assessment

Tech stack
c
Domain
audio-video-rtc, cli
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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