| /*************************************************************************/ |
| /* */ |
| /* Language Technologies Institute */ |
| /* Carnegie Mellon University */ |
| /* Copyright (c) 2010 */ |
| /* All Rights Reserved. */ |
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| /* derived from this software without specific prior written */ |
| /* permission. */ |
| /* */ |
| /* CARNEGIE MELLON UNIVERSITY AND THE CONTRIBUTORS TO THIS WORK */ |
| /* DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING */ |
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| /* ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF */ |
| /* THIS SOFTWARE. */ |
| /* */ |
| /*************************************************************************/ |
| /* Author: Alan W Black (awb@cs.cmu.edu) */ |
| /* Date: March 2001 */ |
| /*************************************************************************/ |
| /* */ |
| /* Minor fixes to make it properly ansi and fit into cst */ |
| /* */ |
| /*************************************************************************/ |
| /* |
| * This source code is a product of Sun Microsystems, Inc. and is provided |
| * for unrestricted use. Users may copy or modify this source code without |
| * charge. |
| * |
| * SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING |
| * THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE. |
| * |
| * Sun source code is provided with no support and without any obligation on |
| * the part of Sun Microsystems, Inc. to assist in its use, correction, |
| * modification or enhancement. |
| * |
| * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE |
| * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE |
| * OR ANY PART THEREOF. |
| * |
| * In no event will Sun Microsystems, Inc. be liable for any lost revenue |
| * or profits or other special, indirect and consequential damages, even if |
| * Sun has been advised of the possibility of such damages. |
| * |
| * Sun Microsystems, Inc. |
| * 2550 Garcia Avenue |
| * Mountain View, California 94043 |
| */ |
| |
| /* |
| * g723_40.c |
| * |
| * Description: |
| * |
| * g723_40_encoder(), g723_40_decoder() |
| * |
| * These routines comprise an implementation of the CCITT G.723 40Kbps |
| * ADPCM coding algorithm. Essentially, this implementation is identical to |
| * the bit level description except for a few deviations which |
| * take advantage of workstation attributes, such as hardware 2's |
| * complement arithmetic. |
| * |
| * The deviation from the bit level specification (lookup tables), |
| * preserves the bit level performance specifications. |
| * |
| * As outlined in the G.723 Recommendation, the algorithm is broken |
| * down into modules. Each section of code below is preceded by |
| * the name of the module which it is implementing. |
| * |
| */ |
| #include "g72x.h" |
| |
| /* |
| * Maps G.723_40 code word to ructeconstructed scale factor normalized log |
| * magnitude values. |
| */ |
| static short _dqlntab[32] = {-2048, -66, 28, 104, 169, 224, 274, 318, |
| 358, 395, 429, 459, 488, 514, 539, 566, |
| 566, 539, 514, 488, 459, 429, 395, 358, |
| 318, 274, 224, 169, 104, 28, -66, -2048}; |
| |
| /* Maps G.723_40 code word to log of scale factor multiplier. */ |
| static short _witab[32] = {448, 448, 768, 1248, 1280, 1312, 1856, 3200, |
| 4512, 5728, 7008, 8960, 11456, 14080, 16928, 22272, |
| 22272, 16928, 14080, 11456, 8960, 7008, 5728, 4512, |
| 3200, 1856, 1312, 1280, 1248, 768, 448, 448}; |
| |
| /* |
| * Maps G.723_40 code words to a set of values whose long and short |
| * term averages are computed and then compared to give an indication |
| * how stationary (steady state) the signal is. |
| */ |
| static short _fitab[32] = {0, 0, 0, 0, 0, 0x200, 0x200, 0x200, |
| 0x200, 0x200, 0x400, 0x600, 0x800, 0xA00, 0xC00, 0xC00, |
| 0xC00, 0xC00, 0xA00, 0x800, 0x600, 0x400, 0x200, 0x200, |
| 0x200, 0x200, 0x200, 0, 0, 0, 0, 0}; |
| |
| static short qtab_723_40[15] = {-122, -16, 68, 139, 198, 250, 298, 339, |
| 378, 413, 445, 475, 502, 528, 553}; |
| |
| /* |
| * g723_40_encoder() |
| * |
| * Encodes a 16-bit linear PCM, A-law or u-law input sample and retuens |
| * the resulting 5-bit CCITT G.723 40Kbps code. |
| * Returns -1 if the input coding value is invalid. |
| */ |
| int |
| g723_40_encoder( |
| int sl, |
| int in_coding, |
| struct g72x_state *state_ptr) |
| { |
| short sei, sezi, se, sez; /* ACCUM */ |
| short d; /* SUBTA */ |
| short y; /* MIX */ |
| short sr; /* ADDB */ |
| short dqsez; /* ADDC */ |
| short dq, i; |
| |
| switch (in_coding) { /* linearize input sample to 14-bit PCM */ |
| case AUDIO_ENCODING_LINEAR: |
| sl >>= 2; /* sl of 14-bit dynamic range */ |
| break; |
| default: |
| return (-1); |
| } |
| |
| sezi = g72x_predictor_zero(state_ptr); |
| sez = sezi >> 1; |
| sei = sezi + g72x_predictor_pole(state_ptr); |
| se = sei >> 1; /* se = estimated signal */ |
| |
| d = sl - se; /* d = estimation difference */ |
| |
| /* quantize prediction difference */ |
| y = g72x_step_size(state_ptr); /* adaptive quantizer step size */ |
| i = g72x_quantize(d, y, qtab_723_40, 15); /* i = ADPCM code */ |
| |
| dq = g72x_reconstruct(i & 0x10, _dqlntab[i], y); /* quantized diff */ |
| |
| sr = (dq < 0) ? se - (dq & 0x7FFF) : se + dq; /* reconstructed signal */ |
| |
| dqsez = sr + sez - se; /* dqsez = pole prediction diff. */ |
| |
| g72x_update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr); |
| |
| return (i); |
| } |
| |
| /* |
| * g723_40_decoder() |
| * |
| * Decodes a 5-bit CCITT G.723 40Kbps code and returns |
| * the resulting 16-bit linear PCM, A-law or u-law sample value. |
| * -1 is returned if the output coding is unknown. |
| */ |
| int |
| g723_40_decoder( |
| int i, |
| int out_coding, |
| struct g72x_state *state_ptr) |
| { |
| short sezi, sei, sez, se; /* ACCUM */ |
| short y; /* MIX */ |
| short sr; /* ADDB */ |
| short dq; |
| short dqsez; |
| |
| i &= 0x1f; /* mask to get proper bits */ |
| sezi = g72x_predictor_zero(state_ptr); |
| sez = sezi >> 1; |
| sei = sezi + g72x_predictor_pole(state_ptr); |
| se = sei >> 1; /* se = estimated signal */ |
| |
| y = g72x_step_size(state_ptr); /* adaptive quantizer step size */ |
| dq = g72x_reconstruct(i & 0x10, _dqlntab[i], y); /* estimation diff. */ |
| |
| sr = (dq < 0) ? (se - (dq & 0x7FFF)) : (se + dq); /* reconst. signal */ |
| |
| dqsez = sr - se + sez; /* pole prediction diff. */ |
| |
| g72x_update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr); |
| |
| switch (out_coding) { |
| case AUDIO_ENCODING_LINEAR: |
| return (sr << 2); /* sr was of 14-bit dynamic range */ |
| default: |
| return (-1); |
| } |
| } |
