| /*************************************************************************/ |
| /* */ |
| /* Language Technologies Institute */ |
| /* Carnegie Mellon University */ |
| /* Copyright (c) 2010 */ |
| /* All Rights Reserved. */ |
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| /* 3. Original authors' names are not deleted. */ |
| /* 4. The authors' names are not used to endorse or promote products */ |
| /* 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 */ |
| /* ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT */ |
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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 |
| */ |
| |
| /* |
| * g721.c |
| * |
| * Description: |
| * |
| * g721_encoder(), g721_decoder() |
| * |
| * These routines comprise an implementation of the CCITT G.721 ADPCM |
| * coding algorithm. Essentially, this implementation is identical to |
| * the bit level description except for a few deviations which |
| * take advantage of work station attributes, such as hardware 2's |
| * complement arithmetic and large memory. Specifically, certain time |
| * consuming operations such as multiplications are replaced |
| * with lookup tables and software 2's complement operations are |
| * replaced with hardware 2's complement. |
| * |
| * The deviation from the bit level specification (lookup tables) |
| * preserves the bit level performance specifications. |
| * |
| * As outlined in the G.721 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" |
| |
| static short qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400}; |
| /* |
| * Maps G.721 code word to reconstructed scale factor normalized log |
| * magnitude values. |
| */ |
| static short _dqlntab[16] = {-2048, 4, 135, 213, 273, 323, 373, 425, |
| 425, 373, 323, 273, 213, 135, 4, -2048}; |
| |
| /* Maps G.721 code word to log of scale factor multiplier. */ |
| static short _witab[16] = {-12, 18, 41, 64, 112, 198, 355, 1122, |
| 1122, 355, 198, 112, 64, 41, 18, -12}; |
| /* |
| * Maps G.721 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[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00, |
| 0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0}; |
| |
| /* |
| * g721_encoder() |
| * |
| * Encodes the input vale of linear PCM, A-law or u-law data sl and returns |
| * the resulting code. -1 is returned for unknown input coding value. |
| */ |
| int |
| g721_encoder( |
| int sl, |
| int in_coding, |
| struct g72x_state *state_ptr) |
| { |
| short sezi, se, sez; /* ACCUM */ |
| short d; /* SUBTA */ |
| short sr; /* ADDB */ |
| short y; /* MIX */ |
| short dqsez; /* ADDC */ |
| short dq, i; |
| |
| switch (in_coding) { /* linearize input sample to 14-bit PCM */ |
| case AUDIO_ENCODING_LINEAR: |
| sl >>= 2; /* 14-bit dynamic range */ |
| break; |
| default: |
| return (-1); |
| } |
| |
| sezi = g72x_predictor_zero(state_ptr); |
| sez = sezi >> 1; |
| se = (sezi + g72x_predictor_pole(state_ptr)) >> 1; /* estimated signal */ |
| |
| d = sl - se; /* estimation difference */ |
| |
| /* quantize the prediction difference */ |
| y = g72x_step_size(state_ptr); /* quantizer step size */ |
| i = g72x_quantize(d, y, qtab_721, 7); /* i = ADPCM code */ |
| |
| dq = g72x_reconstruct(i & 8, _dqlntab[i], y); /* quantized est diff */ |
| |
| sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconst. signal */ |
| |
| dqsez = sr + sez - se; /* pole prediction diff. */ |
| |
| g72x_update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr); |
| |
| return (i); |
| } |
| |
| /* |
| * g721_decoder() |
| * |
| * Description: |
| * |
| * Decodes a 4-bit code of G.721 encoded data of i and |
| * returns the resulting linear PCM, A-law or u-law value. |
| * return -1 for unknown out_coding value. |
| */ |
| int |
| g721_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 &= 0x0f; /* 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); /* dynamic quantizer step size */ |
| |
| dq = g72x_reconstruct(i & 0x08, _dqlntab[i], y); /* quantized diff. */ |
| |
| sr = (dq < 0) ? (se - (dq & 0x3FFF)) : se + dq; /* reconst. signal */ |
| |
| dqsez = sr - se + sez; /* pole prediction diff. */ |
| |
| g72x_update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr); |
| |
| switch (out_coding) { |
| case AUDIO_ENCODING_LINEAR: |
| return (sr << 2); /* sr was 14-bit dynamic range */ |
| default: |
| return (-1); |
| } |
| } |
