kAudioFilePropertySourceBitDepth

For compressed data, this property’s value is the bit depth of the source, uncompressed audio stream as an SInt32 value, if known. The bit depth is expressed as a negative number if the uncompressed source was in a floating point format. For example, a property value of -32 is used for float and a property value of -64 represents double.

var kAudioFilePropertySourceBitDepth: AudioFilePropertyID { get }