         channel = ChannelConfiguration(rawValue: UInt8(asbd.mChannelsPerFrame))!
     }
     
-    func adts(length:Int) -> [UInt8] {
+    /// adts头是一个7bit的数据，通过adts可以获得AAC数据的编码参数
+    func adts(_ length:Int) -> [UInt8] {
         let size:Int = 7
         let fullSize:Int = size + length
         var adts:[UInt8] = [UInt8](repeating: 0x00, count: size)

    }
    
    init?(bytes:[UInt8]) {
        guard let type:AudioObjectType = AudioObjectType(rawValue: bytes[0] >> 3),
            let frequency:SamplingFrequency = SamplingFrequency(rawValue: (bytes[0] & 0b00000111) << 1 | (bytes[1] >> 7)),
            let channel:ChannelConfiguration = ChannelConfiguration(rawValue: (bytes[1] & 0b01111000) >> 3) else {
                return nil
        }
        self.type = type

    }
    
    func createAudioStreamBasicDescription() -> AudioStreamBasicDescription {
        var asbd = AudioStreamBasicDescription()
        asbd.mSampleRate = frequency.sampleRate
        asbd.mFormatID = kAudioFormatMPEG4AAC
        asbd.mFormatFlags = UInt32(type.rawValue)
