FreeCalypso > hg > gsm-codec-lib
view frtest/hand-test.c @ 242:f081a6850fb5
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 | d21c68b8f16c |
children |
line wrap: on
line source
/* * This program is a debug aid that allows a developer to hand-craft input * to the GSM 06.10 decoder (libgsm) and see what output magnitude it results * in, in the style of gsmfr-max-out. This program reads input from an * ASCII text file in the same format as gsmrec-dump, performs gsm_implode() * and gsm_decode() operations and reports maximum output magnitude for * each processed frame. */ #include <ctype.h> #include <stdio.h> #include <stdint.h> #include <stdlib.h> #include <string.h> #include <strings.h> #include <gsm.h> static char *infname; static FILE *inf; static char linebuf[256]; static int lineno; static get_line() { if (!fgets(linebuf, sizeof linebuf, inf)) return 0; lineno++; if (!index(linebuf, '\n')) { fprintf(stderr, "%s line %d: too long or missing newline\n", infname, lineno); exit(1); } return 1; } static read_lar_params(params) gsm_signal *params; { char *cp; unsigned n; for (;;) { if (!get_line()) return 0; for (cp = linebuf; isspace(*cp); cp++) ; if (*cp) break; } if (*cp == '#') { cp++; if (!isdigit(*cp)) { inv_syntax: fprintf(stderr, "%s line %d: invalid syntax (expected LAR)\n", infname, lineno); exit(1); } while (isdigit(*cp)) cp++; if (*cp++ != ':') goto inv_syntax; while (isspace(*cp)) cp++; } if (cp[0] != 'F' || cp[1] != 'R' || !isspace(cp[2])) goto inv_syntax; cp += 3; for (n = 0; n < 8; n++) { while (isspace(*cp)) cp++; if (!isdigit(*cp)) goto inv_syntax; params[n] = strtoul(cp, &cp, 10); if (!isspace(*cp)) goto inv_syntax; } fputs(linebuf, stdout); return 1; } static void read_subframe_params(params) gsm_signal *params; { char *cp; unsigned n; for (;;) { if (!get_line()) { fprintf(stderr, "%s bad: EOF in the middle of a frame\n", infname); exit(1); } for (cp = linebuf; isspace(*cp); cp++) ; if (*cp) break; } for (n = 0; n < 17; n++) { while (isspace(*cp)) cp++; if (!isdigit(*cp)) { inv_syntax: fprintf(stderr, "%s line %d: invalid syntax (expected subframe)\n", infname, lineno); exit(1); } params[n] = strtoul(cp, &cp, 10); if (!isspace(*cp)) goto inv_syntax; } fputs(linebuf, stdout); } static read_frame(params) gsm_signal *params; { int rc; unsigned n, idx; rc = read_lar_params(params); if (!rc) return 0; idx = 8; for (n = 0; n < 4; n++) { read_subframe_params(params + idx); idx += 17; } return 1; } main(argc, argv) char **argv; { gsm dec_state; gsm_signal params[76]; uint8_t frame[33]; int16_t pcm[160]; int rc, i; unsigned samp_abs, samp_max; if (argc != 2) { fprintf(stderr, "usage: %s input-file\n", argv[0]); exit(1); } infname = argv[1]; inf = fopen(infname, "r"); if (!inf) { perror(infname); exit(1); } dec_state = gsm_create(); if (!dec_state) { fprintf(stderr, "gsm_create() failed!\n"); exit(1); } for (;;) { rc = read_frame(params); if (!rc) break; gsm_implode(dec_state, params, frame); gsm_decode(dec_state, frame, pcm); samp_max = 0; for (i = 0; i < 160; i++) { if (pcm[i] >= 0) samp_abs = pcm[i]; else samp_abs = -pcm[i]; if (samp_abs > samp_max) samp_max = samp_abs; } printf(" MAX=%u\n", samp_max); } exit(0); }