fix pcm播放卡顿的问题

Author: zhaoyongqiang

iOS/APIExample/Common/ExternalAudio/AgoraPcmSourcePush.swift

@@ -60,10 +60,13 @@ class AgoraPcmSourcePush: NSObject {
             let sleepTime = TimeInterval(self.samples) / TimeInterval(self.sampleRate)
             let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: bufferSize)
             while input.hasBytesAvailable && self.state == .Play {
+                let beforePush = CFAbsoluteTimeGetCurrent()
                 input.read(buffer, maxLength: bufferSize)
 //                self.delegate?.onAudioFrame(data: Data(bytes: buffer, count: bufferSize))
                 self.delegate?.onAudioFrame(data: buffer)
-                Thread.sleep(forTimeInterval: sleepTime)
+                let afterPush = CFAbsoluteTimeGetCurrent()
+                let sleep = sleepTime - (afterPush - beforePush)
+                Thread.sleep(forTimeInterval: sleep)
             }
             buffer.deallocate()
             input.close()

iOS/APIExample/Examples/Advanced/CustomPcmAudioSource/CustomPcmAudioSource.swift

@@ -52,7 +52,7 @@ class CustomPcmAudioSourceMain: BaseViewController {
         }
     }
 
-    let sampleRate:UInt = 44100, channel:UInt = 2, bitPerSample = 16, samples = 441 * 10
+    let sampleRate:UInt = 44100, channel:UInt = 1, bitPerSample = 16, samples = 441 * 10
     override func viewDidLoad(){
         super.viewDidLoad()