jitter buffer with variable size data

Is it possible to use the jitter buffer with a variable number of frames in each packet? The only thing I've had luck with is using a fixed number of frames per packet, 1 in this case (which is sort of a hassle because speex over RTP allows an arbitrary number of packets).

I either get errors that there is negative buffering or it complains that it lost start_offset (because I passed in NULL).

I think it boils down to my not understanding what the purpose of the span parameter is. From a cursory glance at the code, it looks like it'll just give me the earliest packet, no matter what I ask for, but it adjusts the buffering based on the parameter.

If it only works with a single frame per packet, then is there an easy way to separate the frames in the RTP packet? I could probably modify the code that was posted to the list years ago for counting the number of frames in a SpeexBits to split them up. Making each frame be an integral number of bytes by inserting the terminator after encoding each frame would help with that, I suppose.

Thanks for any help.

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Steve Checkoway