https://developer.apple.com/documentation/coreaudiotypes/kaudioformatmpeg4aac_eld?language=objc
kAudioFormatMPEG4AAC_ELD | Apple Developer Documentation
A key that specifies the MPEG-4 Enhanced Low Delay AAC codec, and uses no flags.
apple developerelddocumentation
https://developer.apple.com/documentation/coreaudiotypes/kaudioformatmpeg4aac?language=objc
kAudioFormatMPEG4AAC | Apple Developer Documentation
A key that specifies the MPEG-4 AAC Low Complexity codec, and uses no flags.
apple developerdocumentation
https://developer.apple.com/documentation/coreaudiotypes/kaudioformatmpeg4aac_ld?language=objc
kAudioFormatMPEG4AAC_LD | Apple Developer Documentation
A key that specifies the MPEG-4 Low Delay AAC codec, and uses no flags.
apple developerlddocumentation