Real-time or unbuffered (NetStream.bufferTime=0) live video playback becomes choppy when audio is muted or there is silence and Aggregate Messages are enabled in Flash Media Server. Aggregate Messages allow Flash Media Server to combine all messages (audio, data, and video) into chunks to send to the flash player. The server does not send audio messages when the source audio is muted or silenced. If the flash player receives message chunks without audio messages and there is no client-side buffer, the player does not render the video messages. Video playback becomes smooth when audio returns.
Either disable Aggregate Messages in the Application.xml configuration file or configure a client-side buffer (default is 0.1 seconds).
Note: Increasing the client-side buffer is preferred because disabling Aggregate Messages impacts server performance.