How to detect unplayable video channel?

I'm using NetConnection, NetStream and a flash.media.Video control to play back video files stored on the local machine. Works great for FLVs, and for H.264-encoded MP4s, but for non-H.264 MP4s, I often get audio, but no video.

I realize this is to be expected. What I'm wondering is whether there's开发者_StackOverflow社区 a way to reliably detect that the video portion of the file is unplayable, irrespective of the audio. Of the many events available in NetStream, and even in the client callbacks (onMetaData, etc.), I don't see anything that explicitly informs for an unplayable video track -- I see NetStream.Play.NoSupportedTrackFound, and NetStream.Play.Failed, but for these videos -- i.e., playable audio, non-playable video -- I don't get either one, presumably because the audio works.

Is there anything better than attempting to make an inductive guess about this? Anyone solved this issue before? I'm sure I'm probably just overlooking something.

Thanks in advance --

This is a problem even experienced by YouTube. However, you may try using a streaming server like Red5 to see if it can detect a bad video instance.