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V2 Beat-Synchronized Transitions

BeatSynchronizedTransitions_V2_Contract.json

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Phase 72.22.1.4 adds beat-synchronized transition scheduling for Maya adaptive music. It waits until the next authored beat, bar, or phrase boundary before a music segment switch is allowed.

Source Of Truth#

  • Contract: BeatSynchronizedTransitions_V2_Contract.json
  • Runtime module: V2Audio
  • Core types: EV2MusicSyncBoundary, FV2BeatSynchronizedTransitionRule, FV2BeatSynchronizedTransitionRequest, FV2ResolvedBeatSynchronizedTransition, and FV2BeatSynchronizedTransitionPlan
  • Builder: UV2AudioBlueprintLibrary::BuildDefaultBeatSynchronizedTransitionPlan
  • Validator: UV2AudioBlueprintLibrary::ValidateBeatSynchronizedTransitionPlan
  • Resolver: UV2AudioBlueprintLibrary::ResolveBeatSynchronizedTransition
  • Registrar: UV2AudioSubsystem::RegisterBeatSynchronizedTransitionPlan
  • Subsystem route: UV2AudioSubsystem::ScheduleBeatSynchronizedTransition

Boundary Rules#

The default plan validates Beat, Bar, and Phrase boundaries. Rules are authored against segment ids used by the horizontal re-sequencing and adaptive state tasks.

Boundary Example transition
Beat Music.State.Combat.Main to Music.State.Defeat.KO
Bar Music.Section.Exploration.Verse to Music.Section.Exploration.Chorus
Phrase Music.Section.Exploration.Chorus to Music.Section.Exploration.Bridge

Required rule ids include:

  • Music.Section.Exploration.Verse->Music.Section.Exploration.Chorus
  • Music.Section.Exploration.Chorus->Music.Section.Exploration.Bridge
  • Music.State.Combat.Main->Music.State.Defeat.KO

Wait Math#

FV2BeatSynchronizedTransitionPlan::ResolveTransition converts playback time to beats using BPM, finds the next boundary period, and returns WaitSeconds, TargetBeatIndex, TargetBarIndex, and TargetPhraseIndex. This task owns the boundary scheduler only; later tempo-detection work can feed measured BPM into the same request through OverrideBpm.

Runtime Evidence#

UV2AudioConfigAsset owns the default FV2BeatSynchronizedTransitionPlan. UV2AudioSubsystem registers it, schedules transitions, stores the last accepted transition, and exposes rule count, beat coverage, bar coverage, phrase coverage, target segment, and wait time through FV2AudioRuntimeSnapshot.

Validation Commands#

bash
python3 V2/ue/Tools/check-v2-beat-synchronized-transitions.py
python3 V2/ue/Tools/check-v2-vertical-music-layering.py
python3 V2/ue/Tools/check-v2-audio-module.py
python3 -m json.tool V2/ue/Content/V2/Audio/BeatSynchronizedTransitions_V2_Contract.json
python3 V2/tools/validate-v2-docs.py