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Defines | |
#define | AST_LIN2MU(a) (__ast_lin2mu[((unsigned short)(a)) >> 2]) |
#define | AST_MULAW(a) (__ast_mulaw[(a)]) |
#define | AST_ULAW_BIT_LOSS 3 |
#define | AST_ULAW_SIGN_BIT 0x80 |
#define | AST_ULAW_STEP (1 << AST_ULAW_BIT_LOSS) |
#define | AST_ULAW_TAB_SIZE (32768 / AST_ULAW_STEP + 1) |
Functions | |
void | ast_ulaw_init (void) |
Set up mu-law conversion table. | |
Variables | |
unsigned char | __ast_lin2mu [16384] |
converts signed linear to mulaw | |
short | __ast_mulaw [256] |
Definition in file ulaw.h.
#define AST_LIN2MU | ( | a | ) | (__ast_lin2mu[((unsigned short)(a)) >> 2]) |
Definition at line 49 of file ulaw.h.
Referenced by ast_ulaw_init(), fill_rxgain(), fill_txgain(), lintoulaw(), lintoulaw_framein(), load_module(), and make_tone_burst().
#define AST_MULAW | ( | a | ) | (__ast_mulaw[(a)]) |
Definition at line 85 of file ulaw.h.
Referenced by ast_dsp_process(), ast_ulaw_init(), calc_energy(), fill_rxgain(), fill_txgain(), load_module(), tdd_feed(), ulawtolin(), and ulawtolin_framein().
#define AST_ULAW_STEP (1 << AST_ULAW_BIT_LOSS) |
void ast_ulaw_init | ( | void | ) |
Set up mu-law conversion table.
To init the ulaw to slinear conversion stuff, this needs to be run.
Definition at line 170 of file ulaw.c.
References AST_LIN2MU, ast_log(), AST_MULAW, AST_ULAW_STEP, f, linear2ulaw(), LOG_NOTICE, and LOG_WARNING.
Referenced by load_module(), and main().
00171 { 00172 int i; 00173 00174 /* 00175 * Set up mu-law conversion table 00176 */ 00177 #ifndef G711_NEW_ALGORITHM 00178 for (i = 0;i < 256;i++) { 00179 short mu,e,f,y; 00180 static short etab[]={0,132,396,924,1980,4092,8316,16764}; 00181 00182 mu = 255-i; 00183 e = (mu & 0x70)/16; 00184 f = mu & 0x0f; 00185 y = f * (1 << (e + 3)); 00186 y += etab[e]; 00187 if (mu & 0x80) y = -y; 00188 __ast_mulaw[i] = y; 00189 } 00190 /* set up the reverse (mu-law) conversion table */ 00191 for (i = -32768; i < 32768; i++) { 00192 __ast_lin2mu[((unsigned short)i) >> 2] = linear2ulaw(i); 00193 } 00194 #else 00195 00196 for (i = 0; i < 256; i++) { 00197 __ast_mulaw[i] = ulaw2linear(i); 00198 } 00199 /* set up the reverse (mu-law) conversion table */ 00200 for (i = 0; i <= 32768; i += AST_ULAW_STEP) { 00201 AST_LIN2MU_LOOKUP(i) = linear2ulaw(i, 0 /* half-cooked */); 00202 } 00203 #endif 00204 00205 #ifdef TEST_CODING_TABLES 00206 for (i = -32768; i < 32768; ++i) { 00207 #ifndef G711_NEW_ALGORITHM 00208 unsigned char e1 = linear2ulaw(i); 00209 #else 00210 unsigned char e1 = linear2ulaw(i, 1); 00211 #endif 00212 short d1 = ulaw2linear(e1); 00213 unsigned char e2 = AST_LIN2MU(i); 00214 short d2 = ulaw2linear(e2); 00215 short d3 = AST_MULAW(e1); 00216 00217 if (e1 != e2 || d1 != d3 || d2 != d3) { 00218 ast_log(LOG_WARNING, "u-Law coding tables test failed on %d: e1=%u, e2=%u, d1=%d, d2=%d\n", 00219 i, (unsigned)e1, (unsigned)e2, (int)d1, (int)d2); 00220 } 00221 } 00222 ast_log(LOG_NOTICE, "u-Law coding table test complete.\n"); 00223 #endif /* TEST_CODING_TABLES */ 00224 00225 #ifdef TEST_TANDEM_TRANSCODING 00226 /* tandem transcoding test */ 00227 for (i = -32768; i < 32768; ++i) { 00228 unsigned char e1 = AST_LIN2MU(i); 00229 short d1 = AST_MULAW(e1); 00230 unsigned char e2 = AST_LIN2MU(d1); 00231 short d2 = AST_MULAW(e2); 00232 unsigned char e3 = AST_LIN2MU(d2); 00233 short d3 = AST_MULAW(e3); 00234 00235 if (i < 0 && e1 == 0x7f && e2 == 0xff && e3 == 0xff) 00236 continue; /* known and normal negative 0 case */ 00237 00238 if (e1 != e2 || e2 != e3 || d1 != d2 || d2 != d3) { 00239 ast_log(LOG_WARNING, "u-Law tandem transcoding test failed on %d: e1=%u, e2=%u, d1=%d, d2=%d, d3=%d\n", 00240 i, (unsigned)e1, (unsigned)e2, (int)d1, (int)d2, (int)d3); 00241 } 00242 } 00243 ast_log(LOG_NOTICE, "u-Law tandem transcoding test complete.\n"); 00244 #endif /* TEST_TANDEM_TRANSCODING */ 00245 }
unsigned char __ast_lin2mu[16384] |
short __ast_mulaw[256] |