--- /dev/null
+/*
+ * 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"
+#include "g72x_priv.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, 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;
+
+ /* linearize input sample to 14-bit PCM */
+ sl >>= 2; /* sl of 14-bit dynamic range */
+
+ sezi = predictor_zero(state_ptr);
+ sez = sezi >> 1;
+ sei = sezi + predictor_pole(state_ptr);
+ se = sei >> 1; /* se = estimated signal */
+
+ d = sl - se; /* d = estimation difference */
+
+ /* quantize prediction difference */
+ y = step_size(state_ptr); /* adaptive quantizer step size */
+ i = quantize(d, y, qtab_723_40, 15); /* i = ADPCM code */
+
+ dq = 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. */
+
+ 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, 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 = predictor_zero(state_ptr);
+ sez = sezi >> 1;
+ sei = sezi + predictor_pole(state_ptr);
+ se = sei >> 1; /* se = estimated signal */
+
+ y = step_size(state_ptr); /* adaptive quantizer step size */
+ dq = 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. */
+
+ update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
+
+ return (sr << 2); /* sr was of 14-bit dynamic range */
+}
+
projects / Faustine.git / blobdiff