[Live-devel] Buffering an H264 Video Stream

Mark Bondurant markb at virtualguard.com
Mon Nov 3 13:02:46 PST 2014


Hello,

Sorry if this is a repeat, but I/we have constant email problems (political issues), which I'm fairly sure I've now found a workaround for. What I'm saying is that this may be a repeat. If it is, I apologize, I didn't get your responses.

I need to keep a constant 3 second buffer of an H264 video stream. It's for security cameras. When something trips the camera, I replay the 3 seconds and then 6 more to see the event (One hopes I'll catch some ghosts or mountain lions, but really it's to catch car thieves!).  With mpeg it was easy because mpeg has discrete frames, but the much better definition h264 doesn't. I mean it does, but they're spread out over an indefinite series of NAL packets that can contain various varieties of slices. Squishing together into a discrete frame is a problem.

It seems to me that there are two different paradigms at work in live555. Modules that derive from Medium and modules that derive from MediaSource. One seems to clock out of env and the other out of session and they don't fit together with each other.

I need RTSPClient to interface with the camera, which derives from Medium. It understands the RTSP Describe and Setup responses, but it only fits with its Filesinks. I need H264DiscreteFramer filter because it understands how to gather together NAL packets into frames. Unfortunately Discrete Framer wants it's input from an input source that derives from MediaSource, not Medium, which RTSPClient derives from. RTSPClient doesn't fit  together with H264DiscreteFramer! (clunk, clunk, me trying to squish them together).

When things don't fit, I think that I'm missing something important. So what I'm asking for is a clue. What am I missing?

Mark
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