A-Law to Signed linear conversion. More...
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Defines | |
#define | AST_ALAW(a) (__ast_alaw[(int)(a)]) |
#define | AST_ALAW_AMI_MASK 0x55 |
#define | AST_ALAW_BIT_LOSS 4 |
#define | AST_ALAW_SIGN_BIT 0x80 |
#define | AST_ALAW_STEP (1 << AST_ALAW_BIT_LOSS) |
#define | AST_ALAW_TAB_SIZE (32768 / AST_ALAW_STEP + 1) |
#define | AST_LIN2A(a) (__ast_lin2a[((unsigned short)(a)) >> 3]) |
Functions | |
void | ast_alaw_init (void) |
To init the alaw to slinear conversion stuff, this needs to be run. | |
Variables | |
short | __ast_alaw [256] |
unsigned char | __ast_lin2a [8192] |
converts signed linear to alaw |
A-Law to Signed linear conversion.
Definition in file alaw.h.
#define AST_ALAW | ( | a | ) | (__ast_alaw[(int)(a)]) |
Definition at line 84 of file alaw.h.
Referenced by alawtolin_framein(), ast_alaw_init(), ast_dsp_process(), calc_energy(), fill_rxgain(), fill_txgain(), and load_module().
#define AST_ALAW_STEP (1 << AST_ALAW_BIT_LOSS) |
Definition at line 33 of file alaw.h.
Referenced by ast_alaw_init().
#define AST_LIN2A | ( | a | ) | (__ast_lin2a[((unsigned short)(a)) >> 3]) |
Definition at line 50 of file alaw.h.
Referenced by ast_alaw_init(), ast_dsp_process(), fill_rxgain(), fill_txgain(), lintoalaw_framein(), and load_module().
void ast_alaw_init | ( | void | ) |
To init the alaw to slinear conversion stuff, this needs to be run.
Definition at line 150 of file alaw.c.
References alaw2linear(), AST_ALAW, AST_ALAW_STEP, AST_LIN2A, ast_log(), linear2alaw(), LOG_NOTICE, and LOG_WARNING.
Referenced by main().
{ int i; /* * Set up mu-law conversion table */ #ifndef G711_NEW_ALGORITHM for (i = 0; i < 256; i++) { __ast_alaw[i] = alaw2linear(i); } /* set up the reverse (mu-law) conversion table */ for (i = -32768; i < 32768; i++) { __ast_lin2a[((unsigned short)i) >> 3] = linear2alaw(i); } #else for (i = 0; i < 256; i++) { __ast_alaw[i] = alaw2linear(i); } /* set up the reverse (a-law) conversion table */ for (i = 0; i <= 32768; i += AST_ALAW_STEP) { AST_LIN2A_LOOKUP(i) = linear2alaw(i, 0 /* half-cooked */); } #endif #ifdef TEST_CODING_TABLES for (i = -32768; i < 32768; ++i) { #ifndef G711_NEW_ALGORITHM unsigned char e1 = linear2alaw(i); #else unsigned char e1 = linear2alaw(i, 1); #endif short d1 = alaw2linear(e1); unsigned char e2 = AST_LIN2A(i); short d2 = alaw2linear(e2); short d3 = AST_ALAW(e1); if (e1 != e2 || d1 != d3 || d2 != d3) { ast_log(LOG_WARNING, "a-Law coding tables test failed on %d: e1=%u, e2=%u, d1=%d, d2=%d\n", i, (unsigned)e1, (unsigned)e2, (int)d1, (int)d2); } } ast_log(LOG_NOTICE, "a-Law coding tables test complete.\n"); #endif /* TEST_CODING_TABLES */ #ifdef TEST_TANDEM_TRANSCODING /* tandem transcoding test */ for (i = -32768; i < 32768; ++i) { unsigned char e1 = AST_LIN2A(i); short d1 = AST_ALAW(e1); unsigned char e2 = AST_LIN2A(d1); short d2 = AST_ALAW(e2); unsigned char e3 = AST_LIN2A(d2); short d3 = AST_ALAW(e3); if (e1 != e2 || e2 != e3 || d1 != d2 || d2 != d3) { ast_log(LOG_WARNING, "a-Law tandem transcoding test failed on %d: e1=%u, e2=%u, d1=%d, d2=%d, d3=%d\n", i, (unsigned)e1, (unsigned)e2, (int)d1, (int)d2, (int)d3); } } ast_log(LOG_NOTICE, "a-Law tandem transcoding test complete.\n"); #endif /* TEST_TANDEM_TRANSCODING */ }
short __ast_alaw[256] |
unsigned char __ast_lin2a[8192] |