There have been problems with playing video-only (no audio) streams. With wait_key setting disabled several flash players used to wait forever when playing such stream. With the setting enabled it’s much better but still it hangs sometimes. Now an empty audio frame is sent with the first video frame and that completely fixes the problem. That behavior is enabled with wait_video on directive. It’s optional since it’s not needed for audio-only streams.
All the above is true for flash clients only. Ffmpeg-family tools treat such streams in a completely different way. They wait for both (audio and video) streams to appear in RTMP stream until probesize bytes pass through. That setting can (and should) be reduced in real life.
Moreover since 0.9.7 version of nginx-rtmp-module new default values are set for several options:
- wait_key is now ON by default. That’s the most reasonable setting for most cases.
- play_restart is now OFF by default. Several flash players stop streaming on NetStream.Play.Stop and do not resume it later on NetStream.Play.Start which is not what expected.