Hi Carsten,
Thank you for your reply.
I understand the UDVM implementation is not the complete SigComp
implementation, but as per my understanding it is the most significant
part. The other components- compressors, state manager and the
dispatchers (compression and decompression) can be built around the
UDVM using open source components (e.g DEFLATE compression libraries
etc.) Also, of these only the dispatchers would be higher layer/
application specific and thus may have IPR issues. Please correct me if
I'm wrong.
So, I still have the following questions:
a) Has anyone provided a complete UDVM implementation that can be used
in a SigComp module?
b) In your original implementation (of the -05 draft), how was the
compressed message for "This is a test message. What is the answer to
life, the universe and everything ?" generated? Although the
documentation says DEFLATE, I did not get the same result using the
zlib DELFATE implementation. Did I miss something?
c) Is the decompression code for DEFLATE algorithm available in the
UDVM instruction set or in bytecode?
Thanks once again.
Regards,
Simran
Carsten Bormann wrote:
Hi Simran,
2. Has there been any addition to the UDVM
assembler/interpreter since March 2002? Specifically, has the
implementation expanded to work with all the instructions in the UDVM
instruction set? Also does anyone have any programming experience with
the UDVM instruction set that can be shared?
Does "the UDVM assembler/interpreter" refer to my half-baked
implementation of the -05 draft?
I haven't got around to work on this implementation to upgrade it with
respect to the changes we made on the way to RFC3320 and the revised
assembler syntax we agreed on for the implementers guide.
3. I tried out the examples posted by
Carsten and these worked perfectly. However, can anyone tell me how we
got the compressed message in the first place?
A UDVM implementation is not a complete SigComp implementation. In
addition you need:
-- an interface to the higher layer protocol (e.g., SIP)
-- a state manager
-- a portfolio (>= 1) of compression algorithm implementations, and
-- UDVM code to send to the decompressor for each of these.
Clearly, these are significant pieces of work, some of which also have
interesting IPR complications.
Gruesse, Carsten
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