Dear Osmocom community,
Over the past several months I've been working almost exclusively on
improving FR1 and EFR speech handling in the Osmocom GSM network
implementation. All of my Gerrit patches since March have been in
this area, and my two Themyscira-branded public domain libraries for
GSM codecs are also primarily intended for use together with Osmocom,
specifically for implementation of transcoding media gateways that
interconnect an Osmocom GSM network with a non-GSM outside world
such as G.711 PSTN.
Given the knowledge I've gained over months of working in this area,
and seeing that many other Osmocom developers aren't particularly
familiar with these aspects of the specs (understandable: GSM is huge,
can't keep everything in one's head), I would like to do an OsmoDevCall
presentation on the topic of GSM speech handling with traditional
non-AMR codecs. I would like to cover the following subtopics:
* What metadata bits (BFI, UFI, SID, TAF) are defined in the specs for
transport of encoded speech between network elements, beyond the
familiar speech codec bits themselves.
* What exactly are regular speech frames, SID frames, silence frames
(a "silence frame" for FR1 codec is NOT the same thing as a SID frame!)
and bad frame gaps, and which of these categories are allowed or not
allowed to exist at each of the interfaces in the spec-defined GSM
architecture.
* Which transformations are supposed to happen where: which network
elements are responsible for bad frame handling, error concealment,
comfort noise insertion or SID propagation.
* How these architectural principles, originally defined for the T1/E1
environment with TRAUs, can be carried over to an RTP environment.
* Relevant Osmocom components: OsmoBTS and the aspect of OsmoMGW that
interfaces from RTP to T1/E1 Abis.
* What behavior changes have been effected by my patches to OsmoBTS and
supporting libraries that have already been merged, and which behavior
changes are still on my wish list or to-do list to implement and
hopefully get merged.
Looking at the OsmoDevCall wiki page, I see absolutely nothing
scheduled past May, and there was no OsmoDevCall in April - are we out
of presenters? But we have just one problem: it seems that some
people in the senior leadership of Osmocom organization don't want me
presenting on OsmoDevCall, and recently even asked specifically for
presentation ideas from "anyone other than Mychaela". I see two
possible solutions to this problem:
Option 1: If the leaders in question could set aside their personal
dislike of me and allow me to present on highly Osmocom-relevant
topics (such as the FR/HR/EFR codec presentation proposal above) no
different from other Osmocom developers, that would be the best
solution.
Option 2: If those who control the scheduling of presentations on the
official OsmoDevCall platform (the official BigBlueButton instance for
ODC) are not willing to budge, the alternative will be for me and Das
Signal (my dear friend and FreeCalypso sysadmin) to set up our own BBB
instance on our own server, configure it to look and feel exactly like
the official one used for ODC, hold presentations there during those
months when no official ODC presentation takes place due to lack of
non-excluded willing presenters, and invite everyone from Osmocom to
join those unofficial ODC-like presentations.
So - which of the two is it going to be?
Sincerely,
Mother Mychaela,
operator of a non-profit GSM network based on Osmocom,
contributing to Osmocom CNI development in conjuction with that
network operation.