Full 4:2:2/4:4:4 support
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bug
enhancement
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- Merged PRs (30d)
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Description
4:2:2 and 4:4:4 chroma sampling are supported only in a degraded configuration. The following features should be fixed and re-enabled once bugs are resolved:
- inter frames (enabling causes faulty reconstruction output and decoding failure, related to tx size) ("there is some additional processing with sub8x8 motion compensation for 422 chroma")
- sub-8x8 inter blocks
- LRF (enabling causes decoding failure for 4:2:2 input)
- CfL prediction (@barrbrain has indicated that it makes some assumptions about 4:2:0 sampling, but untested)
- https://github.com/xiph/rav1e/issues/1149 (desync caused by CDEF with 4:2:2 only)
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by tracing the existing 4:2:2 and 4:4:4 handling, then review the listed inter-frame, sub-8x8, LRF, CfL, and CDEF limitations. Use issue 1149 for the CDEF desynchronization context. Done means the listed features are safely re-enabled with correct reconstruction and decoding behavior.
Written by the indexing model from the issue text.
Assessment
- Domain
- audio-video-rtc
- Issue type
- Bug
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 25/100