1，添加注释

BFFramework/Classes/PQGPUImage/Source/iOS/MovieOutput.swift

@@ -272,6 +272,7 @@ public class MovieOutput: ImageConsumer, AudioEncodingTarget {
         }
     }
 
+    //取到 pixebuffer
     func renderIntoPixelBuffer(_ pixelBuffer: CVPixelBuffer, framebuffer: Framebuffer) throws {
         CVPixelBufferLockBaseAddress(self.pixelBuffer!, CVPixelBufferLockFlags(rawValue: CVOptionFlags(0)))