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# MPEG4ObjectID

Constants that define the type of MPEG-4 audio data.

```
enum MPEG4ObjectID
```

## Topics

### Enumeration Cases

### Constants

[`kMPEG4Object_AAC_LC`](/documentation/CoreAudioTypes/MPEG4ObjectID/AAC_LC)

A constant that specifies lossless coding, which provides compression with no loss of quality.

[`kMPEG4Object_AAC_LTP`](/documentation/CoreAudioTypes/MPEG4ObjectID/AAC_LTP)

A constant that specifies long-term prediction, which reduces redundancy in a coded signal.

[`kMPEG4Object_AAC_Main`](/documentation/CoreAudioTypes/MPEG4ObjectID/aac_Main)

A constant that specifies advanced audio coding, which is the basic MPEG-4 technology.

[`kMPEG4Object_AAC_SBR`](/documentation/CoreAudioTypes/MPEG4ObjectID/AAC_SBR)

A constant that specifies spectral band replication, which reconstructs high-frequency content from lower frequencies and side information.

[`kMPEG4Object_AAC_SSR`](/documentation/CoreAudioTypes/MPEG4ObjectID/AAC_SSR)

A constant that specifies scalable sampling rate, which provides different sampling frequencies for different targets.

[`kMPEG4Object_AAC_Scalable`](/documentation/CoreAudioTypes/MPEG4ObjectID/aac_Scalable)

A constant that specifies scalable lossless coding.

[`kMPEG4Object_CELP`](/documentation/CoreAudioTypes/MPEG4ObjectID/CELP)

A constant that specifies code-excited linear prediction, which is a narrow-band/wide-band speech codec.

[`kMPEG4Object_HVXC`](/documentation/CoreAudioTypes/MPEG4ObjectID/HVXC)

A constant that specifies harmonic vector excitation coding, which is a very-low bit-rate parametric speech codec.

[`kMPEG4Object_TwinVQ`](/documentation/CoreAudioTypes/MPEG4ObjectID/twinVQ)

A constant that specifies transform-domain weighted interleaved vector quantization.

## Relationships

### Conforms To

[`Sendable`](/documentation/Swift/Sendable)

[`SendableMetatype`](/documentation/Swift/SendableMetatype)

[`Equatable`](/documentation/Swift/Equatable)

[`BitwiseCopyable`](/documentation/Swift/BitwiseCopyable)

[`Hashable`](/documentation/Swift/Hashable)

[`RawRepresentable`](/documentation/Swift/RawRepresentable)

---

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