diff options
author | murf <murf@f38db490-d61c-443f-a65b-d21fe96a405b> | 2007-08-20 22:53:48 +0000 |
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committer | murf <murf@f38db490-d61c-443f-a65b-d21fe96a405b> | 2007-08-20 22:53:48 +0000 |
commit | 8b5681e22acd883fc692455b460a6385e521b683 (patch) | |
tree | ba8c79a84cc6cbddcd2d849a6b9895d6124c4452 /main/alaw.c | |
parent | 160c516178ec81b8a2321f84b18ea8cece00f142 (diff) |
This change set fixes bug 8126 in trunk. It is implemented via compile time options, activated via the menuselect stuff, which defaults to the old way. non-zero sample data added. Translate tables expressed in microseconds instead of milliseconds, with 5-digit data now instead of 3, giving 2 more digits of precision.
git-svn-id: http://svn.digium.com/svn/asterisk/trunk@80113 f38db490-d61c-443f-a65b-d21fe96a405b
Diffstat (limited to 'main/alaw.c')
-rw-r--r-- | main/alaw.c | 138 |
1 files changed, 127 insertions, 11 deletions
diff --git a/main/alaw.c b/main/alaw.c index d388d1e61..fbc99b0fe 100644 --- a/main/alaw.c +++ b/main/alaw.c @@ -18,7 +18,7 @@ /*! \file * - * \brief u-Law to Signed linear conversion + * \brief a-Law to Signed linear conversion * * \author Mark Spencer <markster@digium.com> */ @@ -28,18 +28,20 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$") #include "asterisk/alaw.h" +#include "asterisk/logger.h" +#ifndef G711_NEW_ALGORITHM #define AMI_MASK 0x55 -static inline unsigned char linear2alaw (short int linear) +static inline unsigned char linear2alaw(short int linear) { int mask; int seg; int pcm_val; static int seg_end[8] = - { - 0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF - }; + { + 0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF + }; pcm_val = linear; if (pcm_val >= 0) { @@ -50,7 +52,7 @@ static inline unsigned char linear2alaw (short int linear) mask = AMI_MASK; pcm_val = -pcm_val; } - + /* Convert the scaled magnitude to segment number. */ for (seg = 0; seg < 8; seg++) { if (pcm_val <= seg_end[seg]) @@ -59,13 +61,56 @@ static inline unsigned char linear2alaw (short int linear) /* Combine the sign, segment, and quantization bits. */ return ((seg << 4) | ((pcm_val >> ((seg) ? (seg + 3) : 4)) & 0x0F)) ^ mask; } -/*- End of function --------------------------------------------------------*/ +#else +static unsigned char linear2alaw(short sample, int full_coding) +{ + static const unsigned exp_lut[128] = { + 1,1,2,2,3,3,3,3, + 4,4,4,4,4,4,4,4, + 5,5,5,5,5,5,5,5, + 5,5,5,5,5,5,5,5, + 6,6,6,6,6,6,6,6, + 6,6,6,6,6,6,6,6, + 6,6,6,6,6,6,6,6, + 6,6,6,6,6,6,6,6, + 7,7,7,7,7,7,7,7, + 7,7,7,7,7,7,7,7, + 7,7,7,7,7,7,7,7, + 7,7,7,7,7,7,7,7, + 7,7,7,7,7,7,7,7, + 7,7,7,7,7,7,7,7, + 7,7,7,7,7,7,7,7, + 7,7,7,7,7,7,7,7 }; + unsigned sign, exponent, mantissa, mag; + unsigned char alawbyte; + + ast_alaw_get_sign_mag(sample, &sign, &mag); + if (mag > 32767) + mag = 32767; /* clip the magnitude for -32768 */ + + exponent = exp_lut[(mag >> 8) & 0x7f]; + mantissa = (mag >> (exponent + 3)) & 0x0f; + if (mag < 0x100) + exponent = 0; + + if (full_coding) { + /* full encoding, with sign and xform */ + alawbyte = (unsigned char)(sign | (exponent << 4) | mantissa); + alawbyte ^= AST_ALAW_AMI_MASK; + } else { + /* half-cooked coding -- mantissa+exponent only (for lookup tab) */ + alawbyte = (exponent << 4) | mantissa; + } + return alawbyte; +} +#endif +#ifndef G711_NEW_ALGORITHM static inline short int alaw2linear (unsigned char alaw) { int i; int seg; - + alaw ^= AMI_MASK; i = ((alaw & 0x0F) << 4); seg = (((int) alaw & 0x70) >> 4); @@ -73,8 +118,31 @@ static inline short int alaw2linear (unsigned char alaw) i = (i + 0x100) << (seg - 1); return (short int) ((alaw & 0x80) ? i : -i); } +#else +static inline short alaw2linear(unsigned char alawbyte) +{ + unsigned exponent, mantissa; + short sample; + + alawbyte ^= AST_ALAW_AMI_MASK; + exponent = (alawbyte & 0x70) >> 4; + mantissa = alawbyte & 0x0f; + sample = (mantissa << 4) + 8 /* rounding error */; + if (exponent) + sample = (sample + 0x100) << (exponent - 1); + if (!(alawbyte & 0x80)) + sample = -sample; + return sample; +} +#endif + + +#ifndef G711_NEW_ALGORITHM unsigned char __ast_lin2a[8192]; +#else +unsigned char __ast_lin2a[AST_ALAW_TAB_SIZE]; +#endif short __ast_alaw[256]; void ast_alaw_init(void) @@ -82,14 +150,62 @@ void ast_alaw_init(void) int i; /* * Set up mu-law conversion table - */ + */ +#ifndef G711_NEW_ALGORITHM for (i = 0; i < 256; i++) { - __ast_alaw[i] = alaw2linear(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 */ + } |