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[Didier Barvaux <question276107@xxxxxxxxxxxxxxxxxxxxx>]

Question #276107 on rohc changed:
https://answers.launchpad.net/rohc/+question/276107

    Status: Open => Needs information

Didier Barvaux requested more information:
Hello,

The contexts_nr field represents the number of contexts that are used
for a stream. The ROHC compressor doesn't know exactly when a stream
ends. So, it avoids as much as possible to re-use previous contexts for
new streams. So, contexts_nr will keep increasing until the compressor
reaches the MAX_CID parameter (at that time, the compressor will re-use
the context that was used the least recently because it is most probably
a stream that ended sometimes ago).

Knowing the real number of _active_ streams is impossible from the ROHC
compressor. The ROHC compressor doesn't have the information itself.

Maybe I could add a new API function for applications to tell the ROHC
compressor when a stream ended. This would make contexts_nr more
accurate (if the application helps with the new API) and maybe it would
also helps the ROHC compressor for managing contexts. The ROHC
compressor could re-use contexts with smaller CIDs much earlier, leading
to better compression ratio.

Does your application knows when the stream ended?

Regards,
Didier

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