[Live-devel] Get MPEG-TS timing from .tsx file?

[Ross Finlayson]

> In any case, there's an existence proof countering this argument: YouTube, Hulu, Netflix...  They're all VBR.

They're also all TCP.  But we stream via UDP.  Apples and oranges.  (Things are a lot easier if you're using a request-response protocol (like TCP), and therefore don't mind waiting arbitrarily long for data to get delivered.)

Anyway, what I didn't make sufficiently clear in my January 2011 email was that when I ran my experiment, altering our server code (along with the index file format) to stream TS files using precise (rather than predicted) inter-Transport-Packet durations, it HAD NO EFFECT on the way that VLC (as the RTSP media player client) displayed a VBR TS stream.  I.e., VLC played the stream in the same 'jittery' fashion as before.  It wasn't any better.  It might have even been a bit worse.

It therefore became clear to me that I had been wrong about the 'accurate inter-packet duration calculation' issue being the cause of the problem.  That turned out to be a 'red herring'.  The real problem was the bursty nature of the VBR stream itself.

If you want to transmit a highly VBR stream using a datagram protocol (like RTP), then you need to make sure that your client has a lot of buffering, and with a high 'low water mark' (much higher than the 100ms (I think) default that VLC uses).


Ross Finlayson
Live Networks, Inc.
http://www.live555.com/

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