FreeCalypso > hg > gsm-codec-lib
view dev/efr-bit-packing.c @ 605:63f774192906
gsmhr_decoder_twts002_in(): set BFI=1 SID=1 for invalid SID
When a received TW-TS-002 RTP payload indicates invalid SID,
which of the 3 possible BFI/SID combinations should we pass to
our internal ETSI-based speech decoder or TFO engine?
Our original code passed BFI=0 SID=1, but upon further reflection,
BFI=1 SID=1 is a better choice. In the corner case where received
invalid SID is fed to a full decoder in homed state, setting BFI=1
allows that decoder to emit zeros on PCM and stay homed, instead of
launching into full decoding.
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Thu, 04 Dec 2025 21:01:46 +0000 |
| parents | 9639a44ae2e7 |
| children |
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/* * We would like to generate our EFR RTP frame packing and unpacking code * using bitter and sweet utilities from libgsm, so we'll end up packing * and unpacking EFR just like good old FR. However, because of our * slightly different approach, entering the spec file for bitter and sweet * manually would be tedious and error-prone, hence we are going to * generate it with this program. */ #include <stdio.h> #include <stdlib.h> #define PRM_NO 57 /* table from ETSI EFR code */ static const unsigned bitno[PRM_NO] = { 7, 8, 9, 8, 6, /* LSP VQ */ 9, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 5, /* first subframe */ 6, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 5, /* second subframe */ 9, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 5, /* third subframe */ 6, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 5 /* fourth subframe */ }; main(argc, argv) char **argv; { unsigned n; printf("EFR_MAGIC\t4\n"); for (n = 0; n < PRM_NO; n++) printf("params[%u]\t%u\n", n, bitno[n]); exit(0); }
