---
title: QCCompositionProtocolMusicVisualizer
framework: quartz
role: symbol
role_heading: Global Variable
path: quartz/qccompositionprotocolmusicvisualizer
---

# QCCompositionProtocolMusicVisualizer

A  composition that acts as a visualizer for music.  A conforming composition must use the input key QCCompositionInputAudioPeakKey for the instantaneous audio peak and the QCCompositionInputAudioSpectrumKey  for the instantaneous audio spectrum. It can optionally use the QCCompositionInputTrackInfoKey to indicate it receives information about the current  track and the QCCompositionInputTrackSignalKey to indicate the start of a new track.

## Declaration

```swift
let QCCompositionProtocolMusicVisualizer: String
```

## See Also

### Constants

- [QCCompositionAttributeBuiltInKey](quartz/qccompositionattributebuiltinkey.md)
- [QCCompositionAttributeCategoryKey](quartz/qccompositionattributecategorykey.md)
- [QCCompositionAttributeCopyrightKey](quartz/qccompositionattributecopyrightkey.md)
- [QCCompositionAttributeDescriptionKey](quartz/qccompositionattributedescriptionkey.md)
- [QCCompositionAttributeHasConsumersKey](quartz/qccompositionattributehasconsumerskey.md)
- [QCCompositionAttributeIsTimeDependentKey](quartz/qccompositionattributeistimedependentkey.md)
- [QCCompositionAttributeNameKey](quartz/qccompositionattributenamekey.md)
- [QCCompositionCategoryDistortion](quartz/qccompositioncategorydistortion.md)
- [QCCompositionCategoryStylize](quartz/qccompositioncategorystylize.md)
- [QCCompositionCategoryUtility](quartz/qccompositioncategoryutility.md)
- [QCCompositionInputAudioPeakKey](quartz/qccompositioninputaudiopeakkey.md)
- [QCCompositionInputAudioSpectrumKey](quartz/qccompositioninputaudiospectrumkey.md)
- [QCCompositionInputDestinationImageKey](quartz/qccompositioninputdestinationimagekey.md)
- [QCCompositionInputImageKey](quartz/qccompositioninputimagekey.md)
- [QCCompositionInputPaceKey](quartz/qccompositioninputpacekey.md)