Support DiffSinger pitch local retaking

[KakaruHayate]

No description provided.

[Copilot]

Pull request overview

Adds a user-facing preference and supporting plumbing to enable “local retake” when loading DiffSinger-rendered pitch, so pitch generation/editing can be scoped to selected notes rather than always reprocessing the whole phrase.

Changes:

• Adds a new preference (DiffSingerLocalRetaking) and exposes it in the Preferences UI + string resources.
• Extends pitch loading to accept selected note positions and propagates a per-frame retake mask through RenderPitchResult.
• Updates the “Load rendered pitch” batch edit to only write curve points for retaken frames; adds unit tests for retake helpers.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
OpenUtau/Views/PreferencesDialog.axaml	Adds a toggle for DiffSinger pitch local retaking.
OpenUtau/ViewModels/PreferencesViewModel.cs	Wires the new toggle to persisted preferences.
OpenUtau/Strings/Strings.axaml	Adds EN string for the new toggle label.
OpenUtau/Strings/Strings.zh-CN.axaml	Adds zh-CN string for the new toggle label.
OpenUtau.Core/Util/Preferences.cs	Persists the new boolean preference with defaults.
OpenUtau.Core/Render/IRenderer.cs	Adds retake mask to pitch result and a pitch-load overload that accepts selected note positions.
OpenUtau.Core/Editing/NoteBatchEdits.cs	Uses the retake mask to skip writing curve points for non-retaken frames.
OpenUtau.Core/DiffSinger/DiffSingerRetake.cs	Adds helper utilities for mapping selection → note indexes and building a frame mask.
OpenUtau.Core/DiffSinger/DiffSingerRenderer.cs	Implements selection-aware pitch loading for DiffSinger when enabled by preference.
OpenUtau.Core/DiffSinger/DiffSingerPitch.cs	Adds support for partial retake in pitch predictor (retake mask + optional existing pitch).
OpenUtau.Test/Core/DiffSinger/DiffSingerRetakeTest.cs	Adds unit tests for the new retake helper logic.

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[KakaruHayate]

English description:

Support DiffSinger pitch local retaking

When users edit pitch of specific notes in DiffSinger, the pitch predictor currently regenerates pitch for the entire phrase. This PR introduces "pitch local retaking" — only the edited notes are re-predicted; unchanged notes keep their existing pitch frames, significantly reducing edit-to-audible feedback latency.

How it works

• DsPitch.Process() now accepts optional retakeNoteIndexes (which real-pitch notes changed) and existingPitch (the last rendered pitch buffer).
• When provided, it builds a "retake frame mask" via DiffSingerRetake.BuildRetakeFrameMask(), mapping padded segments back to real note indexes. Only frames belonging to the given note indexes are regenerated; the rest are copied from existingPitch.
• LoadRenderedPitch (NoteBatchEdit) now passes the currently selected note indexes as retake candidates.
• A retakeMask is included in the returned RenderPitchResult, so downstream consumers (e.g., note batch edits that process rendered pitch) can filter out unchanged frames.

Configuration

• A new preference DiffSingerPitchRetake (default: true) controls whether the feature is active. Disabling it restores the original full-phrase re-prediction behavior.
• The feature requires DiffSinger tensor cache to be enabled for reasonable performance (re-fetching previously computed encoder outputs from cache instead of re-running the encoder for unchanged frames).

Files changed (11 files, +318 / -6)

• OpenUtau.Core/DiffSinger/DiffSingerRetake.cs (new) — retake frame mask builder
• OpenUtau.Core/DiffSinger/DiffSingerPitch.cs — retake parameter plumbing + mask integration
• OpenUtau.Core/DiffSinger/DiffSingerRenderer.cs — expose FrameMs for mask building
• OpenUtau.Core/Editing/NoteBatchEdits.cs — pass selected note indexes to LoadRenderedPitch
• OpenUtau.Core/Render/IRenderer.cs — add retakeMask to RenderPitchResult
• OpenUtau.Core/Util/Preferences.cs — add DiffSingerPitchRetake setting
• OpenUtau.Test/Core/DiffSinger/DiffSingerRetakeTest.cs (new) — unit tests
• OpenUtau/ViewModels/PreferencesViewModel.cs — wire up the toggle
• OpenUtau/Views/PreferencesDialog.axaml — add toggle UI
• OpenUtau/Strings/Strings.axaml, Strings.zh-CN.axaml — localized strings

Additional change

• The LoadRenderedPitch item in the Notes menu now displays its Ctrl+R keyboard shortcut hint (previously hidden), making the shortcut discoverable.