ref: 42cf355479ef3554a06d39c0d578da803678a118
parent: 13b765c1d1fc4a58c2bc494534fa4f5c8dab5605
author: cbagwell <cbagwell>
date: Fri Nov 23 18:22:46 EST 2001
Adding 2-bit G723 codec.
--- /dev/null
+++ b/src/g723_16.c
@@ -1,0 +1,182 @@
+/*
+ * 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
+ */
+/* 16kbps version created, used 24kbps code and changing as little as possible.
+ * G.726 specs are available from ITU's gopher or WWW site (http://www.itu.ch)
+ * If any errors are found, please contact me at mrand@tamu.edu
+ * -Marc Randolph
+ */
+
+/*
+ * g723_16.c
+ *
+ * Description:
+ *
+ * g723_16_encoder(), g723_16_decoder()
+ *
+ * These routines comprise an implementation of the CCITT G.726 16 Kbps
+ * 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.
+ *
+ */
+#include "st_i.h"
+#include "g711.h"
+#include "g72x.h"
+
+/*
+ * Maps G.723_16 code word to reconstructed scale factor normalized log
+ * magnitude values. Comes from Table 11/G.726
+ */
+static short _dqlntab[4] = { 116, 365, 365, 116}; +
+/* Maps G.723_16 code word to log of scale factor multiplier.
+ *
+ * _witab[4] is actually {-22 , 439, 439, -22}, but FILTD wants it+ * as WI << 5 (multiplied by 32), so we'll do that here
+ */
+static short _witab[4] = {-704, 14048, 14048, -704};+
+/*
+ * Maps G.723_16 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.
+ */
+
+/* Comes from FUNCTF */
+static short _fitab[4] = {0, 0xE00, 0xE00, 0};+
+/* Comes from quantizer decision level tables (Table 7/G.726)
+ */
+static short qtab_723_16[1] = {261};+
+
+/*
+ * g723_16_encoder()
+ *
+ * Encodes a linear PCM, A-law or u-law input sample and returns its 2-bit code.
+ * Returns -1 if invalid input coding value.
+ */
+int
+g723_16_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_ALAW:
+ sl = st_alaw2linear16(sl) >> 2;
+ break;
+ case AUDIO_ENCODING_ULAW:
+ sl = st_ulaw2linear16(sl) >> 2;
+ break;
+ case AUDIO_ENCODING_LINEAR:
+ sl >>= 2; /* sl of 14-bit dynamic range */
+ break;
+ default:
+ return (-1);
+ }
+
+ 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 diff. */
+
+ /* quantize prediction difference d */
+ y = step_size(state_ptr); /* quantizer step size */
+ i = quantize(d, y, qtab_723_16, 1); /* i = ADPCM code */
+
+ /* Since quantize() only produces a three level output
+ * (1, 2, or 3), we must create the fourth one on our own
+ */
+ if (i == 3) /* i code for the zero region */
+ if ((d & 0x8000) == 0) /* If d > 0, i=3 isn't right... */
+ i = 0;
+
+ dq = reconstruct(i & 2, _dqlntab[i], y); /* quantized diff. */
+
+ sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconstructed signal */
+
+ dqsez = sr + sez - se; /* pole prediction diff. */
+
+ update(2, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
+
+ return (i);
+}
+
+/*
+ * g723_16_decoder()
+ *
+ * Decodes a 2-bit CCITT G.723_16 ADPCM 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_16_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 &= 0x03; /* 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 & 0x02, _dqlntab[i], y); /* unquantize pred diff */
+
+ sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq); /* reconst. signal */
+
+ dqsez = sr - se + sez; /* pole prediction diff. */
+
+ update(2, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
+
+ switch (out_coding) {+ case AUDIO_ENCODING_ALAW:
+ return (tandem_adjust_alaw(sr, se, y, i, 2, qtab_723_16));
+ case AUDIO_ENCODING_ULAW:
+ return (tandem_adjust_ulaw(sr, se, y, i, 2, qtab_723_16));
+ case AUDIO_ENCODING_LINEAR:
+ return (sr << 2); /* sr was of 14-bit dynamic range */
+ default:
+ return (-1);
+ }
+}