From: Helmut Hlavacs <[EMAIL PROTECTED]>
Subject: Adaptive Stream Management
Hi There!
I am looking for more detailed information on the RealServer Adaptive
Stream Management ASM.
The documentation provided with the SDK leaves some open questions.
1) I would like to see the rule book rules for the standard
RealAudio/RealVideo encodings.
Is this information visible at
-the server?
-the rm-file?
-the RealPlayer?
-the SDK application testplay (by changin the source code?)
2) Obviously, the current bandwidth is recalculated every second or so -
but how frequently are the ASM rules evaluated? What triggers this? Is
there some kind of smoothing applied to the current bandwidth? The
average bandwidth seems to include the whole streaming session, thus
does not reflect changes in a suitable manner.
3) In the SDK, there is an example rule book for 28.8k connections,
specifying that I-frames and P-frames are separated. Is this also the
case in the standard RealVideo encodings? That would mean that there are
at least two separated streams for RealVideo.
4) The rule book seems to specify exactly, which streams are to be
received at an observed bandwidth. But there are several possible rules
for one and the same situation. For example, if a RM-File contains the
following streams:
Encoded for 28.8k Modem -> target bw is 20k
RealAudio: 8kbps
RealVideo: 12bkps
---------------------
20kbps
Encoded for 56k Modem -> target bw is 32k
RealAudio: 11kbps
RealVideo: 21kbps
---------------------
32kbps
Then there are two possible ways for constructing the rule book:
The simple one
20 < BW < 32: choose streams ecoded for 28.8k modem:
32 < BW: choose streams encoded for 56k modem:
The clever one
20 < BW < 23: 8kbps RA + 12kbps RV
23 < BW < 29: 11kbps RA + 12kbps RV
29 < BW < 32: 8kbps RA + 21kbps RV
32 < BW: 11kbps RA + 21kbps RV
This of course gets more complicated as more target bandwidths are
included into the RM-file.
Which one is used for the standard RealProducer/RealServer encodings?
Does anybody have more information on that?
Thanks in advance
Helmut Hlavacs
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