FreeCalypso > hg > gsm-codec-lib
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libgsmhr1 RxFE: store CN R0+LPC separately from speech
In the original GSM 06.06 code the ECU for speech mode is entirely
separate from the CN generator, maintaining separate state. (The
main intertie between them is the speech vs CN state variable,
distinguishing between speech and CN BFIs, in addition to the
CN-specific function of distinguishing between initial and update
SIDs.)
In the present RxFE implementation I initially thought that we could
use the same saved_frame buffer for both ECU and CN, overwriting
just the first 4 params (R0 and LPC) when a valid SID comes in.
However, I now realize it was a bad idea: the original code has a
corner case (long sequence of speech-mode BFIs to put the ECU in
state 6, then SID and CN-mode BFIs, then a good speech frame) that
would be broken by that buffer reuse approach. We could eliminate
this corner case by resetting the ECU state when passing through
a CN insertion period, but doing so would needlessly increase
the behavioral diffs between GSM 06.06 and our version.
Solution: use a separate CN-specific buffer for CN R0+LPC parameters,
and match the behavior of GSM 06.06 code in this regard.
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Thu, 13 Feb 2025 10:02:45 +0000 |
| parents | a53225b44ea5 |
| children |
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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, libgsmfr2 and libtwamr, the set of 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 (most of these Division 2 command line utilities link with the libraries), but not the other way around: none of the core libraries have any dependency on any other part of this package, not even on each other. Previous versions of gsm-codec-lib suite had a dependency on libgsm, the original GSM 06.10 implementation library from 1990s, and our suite was originally architectured as extending and building on top of libgsm. However, this dependency has now been eliminated, and our new GSM codec libraries and utilities suite is now completely independent from historical libgsm. Compiling and installing Themyscira libraries and utilities =========================================================== The configuration and build process has been fully revamped since previous versions: * You now need to run ./configure before running 'make' - however, please note that our ./configure script is hand-coded, not Autotools/autohell, hence there is no autoreconf nonsense involved. * When you run ./configure, you get the opportunity to either leave CC=, CFLAGS= and the install prefix at their default values, or change them to your own preferences. * There are no more mandatory install-lib and install-utils targets, instead you get standard 'make install' that installs everything into whichever prefix you chose at configure time. (The ability to install only Division 1 components with 'make install-lib' or only Division 2 components with 'make install-utils' is still available, but it is now an experts-only option: if you don't see yourself needing this type of split install, then you don't need it.) The default install prefix is /usr/local, following the general standard for software packages and configure scripts. To change this install location, pass the standard --prefix=/wherever option to ./configure script. In addition to --prefix, our configure script accepts --exec-prefix, --bindir, --includedir and --libdir options, following the common standard. The default compilation settings are CC=gcc and CFLAGS=-O2; to change them, pass CC=my-whatever-cc and/or CFLAGS="-fwhatever-flags" to configure.