FreeCalypso > hg > gsm-codec-lib
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libgsmfrp: new refined implementation
The previous implementation exhibited the following defects,
which are now fixed:
1) The last received valid SID was cached forever for the purpose of
handling future invalid SIDs - we could have received some valid
SID ages ago, then lots of speech or NO_DATA, and if we then get
an invalid SID, we would resurrect the last valid SID from ancient
history - a bad design. In our new design, we handle invalid SID
based on the current state, much like BFI.
2) GSM 06.11 spec says clearly that after the second lost SID
(received BFI=1 && TAF=1 in CN state) we need to gradually decrease
the output level, rather than jump directly to emitting silence
frames - we previously failed to implement such logic.
3) Per GSM 06.12 section 5.2, Xmaxc should be the same in all 4 subframes
in a SID frame. What should we do if we receive an otherwise valid
SID frame with different Xmaxc? Our previous approach would
replicate this Xmaxc oddity in every subsequent generated CN frame,
which is rather bad. In our new design, the very first CN frame
(which can be seen as a transformation of the SID frame itself)
retains the original 4 distinct Xmaxc, but all subsequent CN frames
are based on the Xmaxc from the last subframe of the most recent SID.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Tue, 09 May 2023 05:16:31 +0000 |
parents | 34f8549ff0b1 |
children | 4b6fa53a8240 |
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Dependency graph ================ The complete Themyscira GSM codec libraries & utilities package as presented here consists of two principal parts: Division 1: libgsmefr and libgsmfrp, the two C code libraries intended to be usable by other software; Division 2: various command line utilities that were developed under the umbrella of this project and are being released accordingly. Division 2 components have a compile-time dependency on Division 1 (some of these Division 2 command line utilities link with libgsmefr or libgsmfrp), but not the other way around: neither libgsmefr nor libgsmfrp has any dependency on any other part of this package. However, the original GSM 06.10 library (libgsm) from 1990s is a required dependency for several components of the present Themyscira package: libgsmfrp and several Division 2 command line utilities have a compile-time dependency on <gsm.h> header file provided by libgsm, and several Division 2 utilities also have a link dependency on libgsm itself. Therefore, libgsm should be considered a hard dependency for the present GSM codec libraries & utilities package as a whole, and it needs to be installed system-wide prior to compiling the present software. Compiling and installing Themyscira libraries and utilities =========================================================== Running 'make' at the top level of the present gsm-codec-lib package will compile both Division 1 and Division 2 software components (both libraries and utilities), with the top level Makefile codifying the dependency graph among them. Installation, however, is a little more complicated in that there is no single 'make install' target at the top level - instead of a single install target, the top Makefile provides two separate installation targets: make install-lib Install libgsmefr and libgsmfrp system-wide: gsm_efr.h and gsm_fr_preproc.h are installed in /usr/local/include; libgsmefr.a and libgsmfrp.a are installed in /usr/local/lib. Superuser privileges are usually required to write to these directories. make install-utils Install Division 2 command line utilities into /opt/freecalypso/bin directory, which is non-standard in the muggle world but has been established in our Themyscira community as the location for Themyscira- developed command line utilities working with GSM. The just-described separation between install-lib and install-utils targets has been created because of the difference in install paths: libraries and their header files that need to be easily findable and usable by other people's unrelated software need to be installed under /usr/local, requiring su to root before each install cycle, whereas /opt/freecalypso/bin (writable without root privileges on the Mother's development machine) is much more convenient for Division 2 command line utilities. However, the present gsm-codec-lib package differs from FreeCalypso host tools and SIM tools packages in that in the present package, you ARE allowed to freely change these installation directories to fit your own preferences. FC host tools and FC SIM tools packages carry very strong admonitions in their INSTALL documents to the effect that they MUST be installed under /opt/freecalypso and that this path cannot be changed; this strict imposition is made because of strong intercomponent dependencies within those software suites, with different components invoking each other or looking for their support files using hard- coded absolute pathnames. But the present gsm-codec-lib package is different: you are free to move our Division 2 command line utilities from /opt/freecalypso/bin to /usr/local/bin or anywhere else you like, and you are likewise free to move our Division 1 libraries from /usr/local/{include,lib} to whatever location would be most appropriate in your environment. To change installation directories, you will need to edit subdirectory Makefiles as follows: Division 1: libgsmefr/Makefile libgsmfrp/Makefile Division 2: amrconv/Makefile efrtest/Makefile frtest/Makefile miscutil/Makefile