fix(engine): lower default CRF for better gradient rendering#216
Closed
miguel-heygen wants to merge 1 commit intomainfrom
Closed
fix(engine): lower default CRF for better gradient rendering#216miguel-heygen wants to merge 1 commit intomainfrom
miguel-heygen wants to merge 1 commit intomainfrom
Conversation
Standard preset CRF 23→18, high preset CRF 18→15. The previous CRF values produced visible color banding on dark gradient backgrounds — a recurring issue in eval (prompts 3, 5, 10, 14 all flagged gradient banding). Lower CRF increases file size but eliminates the banding that made otherwise-good compositions look unprofessional. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
3 tasks
Collaborator
Author
This was referenced Apr 7, 2026
4 tasks
Collaborator
Author
|
Removing from stack — CRF change provides marginal improvement. The real fix for gradient banding is the skill guardrail in PR #217. |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary
What it targets
Eval prompts 3, 5, 10, 14 all noted "color banding" on dark gradient backgrounds. Lower CRF preserves more color precision in smooth gradient regions.
Honest assessment
After testing: the CRF reduction provides marginal improvement for dark gradient banding. The visual difference between CRF 23 and 18 is subtle — most of the banding visible in the eval videos comes from the 8-bit color depth of yuv420p, which CRF alone can't fix.
The higher-impact fix is PR #217 (skill guardrails), which tells agents to avoid full-screen dark linear gradients entirely and use radial gradients or solid backgrounds with localized glows instead.
This PR still has value as a general quality bump — CRF 18 is more appropriate for a video rendering tool where output quality matters more than file size.
Trade-off
~30-50% larger file sizes for standard/high quality.
Test plan
pnpm --filter @hyperframes/engine test— all 26 tests pass🤖 Generated with Claude Code