[svn-commits] oej: branch oej/roibos-cng-support-1.8 r373121 - in /team/oej/roibos-cng-supp...
SVN commits to the Digium repositories
svn-commits at lists.digium.com
Tue Sep 18 11:02:15 CDT 2012
Author: oej
Date: Tue Sep 18 11:02:11 2012
New Revision: 373121
URL: http://svnview.digium.com/svn/asterisk?view=rev&rev=373121
Log:
Adding cmantunes res_noise.c with permission from the developer. Disclaimer is in jira/mantis.
Added:
team/oej/roibos-cng-support-1.8/README.roibos-cng.txt (with props)
team/oej/roibos-cng-support-1.8/res/res_noise.c (with props)
Added: team/oej/roibos-cng-support-1.8/README.roibos-cng.txt
URL: http://svnview.digium.com/svn/asterisk/team/oej/roibos-cng-support-1.8/README.roibos-cng.txt?view=auto&rev=373121
==============================================================================
--- team/oej/roibos-cng-support-1.8/README.roibos-cng.txt (added)
+++ team/oej/roibos-cng-support-1.8/README.roibos-cng.txt Tue Sep 18 11:02:11 2012
@@ -1,0 +1,95 @@
+Edvina AB
+Olle E. Johansson
+
+
+Started: 2012-09-18
+
+
+
+
+
+Comfort Noise support in Asterisk 1.8
+=====================================
+
+Current state:
+
+* RTP Channel
+-------------
+
+- Asterisk RTP (res_rtp_asterisk.c) will read CNG packets and produce a warning.
+ These will be forwarded to the core.
+- CNG packets will be sent only as RTP keepalives
+
+* SIP Channel
+-------------
+- The SIP channel will *NOT* negotiate any CNG support if offered, nor
+ offer CNG
+
+* Core
+------
+
+- If a generator is active and CNG is received, Asterisk moves to timer based
+ generation of outbound packets
+- No comfort noise generator exists in core
+
+To add comfort noise support
+----------------------------
+
+- Add SIP negotiation in SDP
+- For inbound streams, generate noise in calls
+- For outbound we can as step 1 just never send any CNG packets
+ - As step 2, add silence detection to calls
+ - Measure noise level
+ - Start sending CNG
+ - Listen for talk detection
+ - Stop sending CNG, send media
+
+References
+----------
+
+- RFC 3389 http://tools.ietf.org/html/rfc3389
+- Appendix II to Recommendation G.711 (02/2000) - A comfort noise
+ payload definition for ITU-T G.711 use in packet-based
+ multimedia communication systems.
+
+
+Terms
+-----
+- DTX Discontinues Transmission capability
+- VAD Voice Activity Detection
+- CN Comfort Noise
+- CNG Comfort Noise Generator
+
+RTP Framing (RFC 3389 section 4)
+--------------------------------
+The RTP header for the comfort noise packet SHOULD be constructed as
+ if the comfort noise were an independent codec. Thus, the RTP
+ timestamp designates the beginning of the comfort noise period.
+
+At the beginning of
+ an inactive voice segment (silence period), a CN packet is
+ transmitted in the same RTP stream and indicated by the CN payload
+ type. The CN packet update rate is left implementation specific. For
+ example, the CN packet may be sent periodically or only when there is
+ a significant change in the background noise characteristics. The
+ CNG algorithm at the receiver uses the information in the CN payload
+ to update its noise generation model and then produce an appropriate
+ amount of comfort noise.
+
+Noise Level (RFC 3389 Section 3.1)
+----------------------------------
+The magnitude of the noise level is packed into the least significant
+ bits of the noise-level byte with the most significant bit unused and
+ always set to 0 as shown below in Figure 1. The least significant
+ bit of the noise level magnitude is packed into the least significant
+ bit of the byte.
+
+ The noise level is expressed in -dBov, with values from 0 to 127
+ representing 0 to -127 dBov. dBov is the level relative to the
+ overload of the system. (Note: Representation relative to the
+ overload point of a system is particularly useful for digital
+ implementations, since one does not need to know the relative
+ calibration of the analog circuitry.) For example, in the case of a
+ u-law system, the reference would be a square wave with values +/-
+ 8031, and this square wave represents 0dBov. This translates into
+ 6.18dBm0.
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Added: team/oej/roibos-cng-support-1.8/res/res_noise.c
URL: http://svnview.digium.com/svn/asterisk/team/oej/roibos-cng-support-1.8/res/res_noise.c?view=auto&rev=373121
==============================================================================
--- team/oej/roibos-cng-support-1.8/res/res_noise.c (added)
+++ team/oej/roibos-cng-support-1.8/res/res_noise.c Tue Sep 18 11:02:11 2012
@@ -1,0 +1,328 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 1999 - 2005, Digium, Inc.
+ *
+ * Contributed by Carlos Antunes <cmantunes at gmail.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*! \file
+ *
+ * \brief Just generate white noise
+ *
+ */
+
+/*** MODULEINFO
+ <support_level>random</support_level>
+ ***/
+
+#include <math.h>
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#include "asterisk/lock.h"
+#include "asterisk/file.h"
+#include "asterisk/logger.h"
+#include "asterisk/channel.h"
+#include "asterisk/pbx.h"
+#include "asterisk/module.h"
+#include "asterisk/app.h"
+
+#ifdef HAVE_EXP10L
+#define FUNC_EXP10 exp10l
+#elif (defined(HAVE_EXPL) && defined(HAVE_LOGL))
+#define FUNC_EXP10(x) expl((x) * logl(10.0))
+#elif (defined(HAVE_EXP) && defined(HAVE_LOG))
+#define FUNC_EXP10(x) (long double)exp((x) * log(10.0))
+#endif
+
+static char *app = "WhiteNoise";
+
+
+/*** DOCUMENTATION
+ <application name="WhiteNoise" language="en_US">
+ <synopsis>
+ Generates white noise
+ </synopsis>
+ <syntax>
+ <parameter name="args">
+ <argument name="timeout" required="true" />
+ <argument name="level" required="false" />
+ </parameter>
+ </syntax>
+ <description>
+ <para>Generates white noise at 'level' dBov's for 'timeout' seconds or indefinitely if timeout
+ is absent or is zero.</para>
+ <para>Level is a non-positive number. For example, WhiteNoise(0.0) generates
+ white noise at full power, while WhiteNoise(-3.0) generates white noise at
+ half full power. Every -3dBov's reduces white noise power in half. Full
+ power in this case is defined as noise that overloads the channel roughly 0.3%
+ of the time. Note that values below -69 dBov's start to give out silence
+ frequently, resulting in intermittent noise, i.e, alternating periods of
+ silence and noise.</para>
+
+ </description>
+ </application>
+***/
+
+static struct ast_frame framedefaults = {
+ .frametype = AST_FRAME_VOICE,
+ .subclass.codec = AST_FORMAT_SLINEAR,
+ .offset = AST_FRIENDLY_OFFSET,
+ .mallocd = 0,
+ .data.ptr = NULL,
+ .datalen = 0,
+ .samples = 0,
+ .src = "whitenoise",
+ .delivery.tv_sec = 0,
+ .delivery.tv_usec = 0
+};
+
+
+#ifndef LOW_MEMORY
+/*
+ * We pregenerate 64k of white noise samples that will be used instead of
+ * generating the samples continously and wasting CPU cycles. The buffer
+ * below stores these pregenerated samples.
+ */
+static float pregeneratedsamples[65536L];
+#endif
+
+/*
+ * We need a nice, not too expensive, gaussian random number generator.
+ * It generates two random numbers at a time, which is great.
+ * From http://www.taygeta.com/random/gaussian.html
+ */
+static void box_muller_rng(float stddev, float *rn1, float *rn2) {
+ const float twicerandmaxinv = 2.0 / RAND_MAX;
+ float x1, x2, w;
+
+ do {
+ x1 = random() * twicerandmaxinv - 1.0;
+ x2 = random() * twicerandmaxinv - 1.0;
+ w = x1 * x1 + x2 * x2;
+ } while (w >= 1.0);
+
+ w = stddev * sqrt((-2.0 * logf(w)) / w);
+ *rn1 = x1 * w;
+ *rn2 = x2 * w;
+}
+
+static void *noise_alloc(struct ast_channel *chan, void *data) {
+ float level = *(float *)data; /* level is noise level in dBov */
+ float *pnoisestddev; /* pointer to calculated noise standard dev */
+ const float maxsigma = 32767.0 / 3.0;
+
+ /*
+ * When level is zero (full power, by definition) standard deviation
+ * (sigma) is calculated so that 3 * sigma equals max sample value
+ * before overload. For signed linear, which is what we use, this
+ * value is 32767. The max value of sigma will therefore be
+ * 32767.0 / 3.0. This guarantees that roughly 99.7% of the samples
+ * generated will be between -32767 and +32767. The rest, 0.3%,
+ * will be clipped to comform to the channel limits, i.e., +/-32767.
+ *
+ */
+ pnoisestddev = malloc(sizeof (float));
+ if(pnoisestddev) {
+ *pnoisestddev = maxsigma * FUNC_EXP10(level / 20.0);
+ }
+ return pnoisestddev;
+}
+
+static void noise_release(struct ast_channel *chan, void *data) {
+ free((float *)data);
+}
+
+static int noise_generate(struct ast_channel *chan, void *data, int len, int samples) {
+#ifdef LOW_MEMORY
+ float randomnumber[2];
+ float sampleamplitude;
+ int j;
+#else
+ uint16_t start;
+#endif
+ float noisestddev = *(float *)data;
+ struct ast_frame f;
+ int16_t *buf, *pbuf;
+ int i;
+
+#ifdef LOW_MEMORY
+ /* We need samples to be an even number */
+ if (samples & 0x1) {
+ ast_log(LOG_WARNING, "Samples (%d) needs to be an even number\n", samples);
+ return -1;
+ }
+#endif
+
+ /* Allocate enough space for samples.
+ * Remember that slin uses signed dword samples */
+ len = samples * sizeof (int16_t);
+ if(!(buf = alloca(len))) {
+ ast_log(LOG_WARNING, "Unable to allocate buffer to generate %d samples\n", samples);
+ return -1;
+ }
+
+ /* Setup frame */
+ memcpy(&f, &framedefaults, sizeof (f));
+ f.data.ptr = buf;
+ f.datalen = len;
+ f.samples = samples;
+
+ /* Let's put together our frame "data" */
+ pbuf = buf;
+
+#ifdef LOW_MEMORY
+ /* We need to generate samples every time we are called */
+ for (i = 0; i < samples; i += 2) {
+ box_muller_rng(noisestddev, &randomnumber[0], &randomnumber[1]);
+ for (j = 0; j < 2; j++) {
+ sampleamplitude = randomnumber[j];
+ if (sampleamplitude > 32767.0)
+ sampleamplitude = 32767.0;
+ else if (sampleamplitude < -32767.0)
+ sampleamplitude = -32767.0;
+ *(pbuf++) = (int16_t)sampleamplitude;
+ }
+ }
+#else
+ /*
+ * We are going to use pregenerated samples. But we start at
+ * different points on the pregenerated samples buffer every time
+ * to create a little bit more randomness
+ *
+ */
+ start = (uint16_t) (65536.0 * random() / RAND_MAX);
+ for (i = 0; i < samples; i++) {
+ *(pbuf++) = (int16_t)(noisestddev * pregeneratedsamples[start++]);
+ }
+#endif
+
+ /* Send it out */
+ if (ast_write(chan, &f) < 0) {
+ ast_log(LOG_WARNING, "Failed to write frame to channel '%s'\n", chan->name);
+ return -1;
+ }
+ return 0;
+}
+
+static struct ast_generator noise_generator =
+{
+ alloc: noise_alloc,
+ release: noise_release,
+ generate: noise_generate,
+} ;
+
+static int noise_exec(struct ast_channel *chan, const char *data) {
+
+ struct ast_module_user *u;
+ char *excessdata;
+ float level = 0;
+ float timeout = 0;
+ char *s;
+ int res;
+
+ AST_DECLARE_APP_ARGS(args,
+ AST_APP_ARG(timeout);
+ AST_APP_ARG(level);
+ );
+
+ /* Verify we potentially have arguments and get local copy */
+ if (!data) {
+ ast_log(LOG_WARNING, "WhiteNoise usage following: WhiteNoise([timeout[, level]])\n");
+ return -1;
+ }
+
+ /* Separate arguments */
+ s = ast_strdupa(data);
+ AST_STANDARD_APP_ARGS(args, s);
+
+ if (args.timeout) {
+ /* Extract second argument, if available, and validate
+ * timeout is non-negative. Zero timeout means no timeout */
+ args.timeout = ast_trim_blanks(args.timeout);
+ timeout = strtof(args.timeout, &excessdata);
+ if ((excessdata && *excessdata) || timeout < 0) {
+ ast_log(LOG_WARNING, "Invalid argument 'timeout': WhiteNoise requires non-negative floating-point argument for timeout in seconds\n");
+ return -1;
+ }
+
+ /* Convert timeout to milliseconds
+ * and ensure minimum of 20ms */
+ timeout = roundf(timeout * 1000.0);
+ if (timeout > 0 && timeout < 20) {
+ timeout = 20;
+ }
+ }
+
+ if (args.level) {
+ /* Extract first argument and ensure we have
+ * a valid noise level argument value */
+ args.level = ast_trim_blanks(args.level);
+ level = strtof(args.level, &excessdata);
+ if ((excessdata && *excessdata) || level > 0) {
+ ast_log(LOG_ERROR, "Invalid argument 'level': WhiteNoise requires non-positive floating-point argument for noise level in dBov's\n");
+ return -1;
+ }
+ }
+
+ ast_debug(1, "Setting up white noise generator with level %.1fdBov's and %.0fms %stimeout\n", level, timeout, timeout == 0 ? "(no) " : "");
+
+ u = ast_module_user_add(chan);
+ ast_set_write_format(chan, AST_FORMAT_SLINEAR);
+ ast_set_read_format(chan, AST_FORMAT_SLINEAR);
+ if (chan->_state != AST_STATE_UP) {
+ ast_answer(chan);
+ }
+ if (ast_activate_generator(chan, &noise_generator, &level) < 0) {
+ ast_log(LOG_WARNING, "Failed to activate white noise generator on '%s'\n",chan->name);
+ res = -1;
+ } else {
+ /* Just do the noise... */
+ res = -1;
+ if (timeout > 0) {
+ res = ast_safe_sleep(chan, timeout);
+ } else {
+ while(!ast_safe_sleep(chan, 10000));
+ }
+ ast_deactivate_generator(chan);
+ }
+ ast_module_user_remove(u);
+ return res;
+}
+
+static int unload_module(void) {
+ ast_module_user_hangup_all();
+
+ return ast_unregister_application(app);
+}
+
+static int load_module(void) {
+#ifndef LOW_MEMORY
+ /* Let's pregenerate all samples with std dev = 1.0 */
+ int i;
+
+ for (i = 0; i < sizeof (pregeneratedsamples) / sizeof (pregeneratedsamples[0]); i += 2) {
+ box_muller_rng(1.0, &pregeneratedsamples[i], &pregeneratedsamples[i + 1]);
+
+ }
+#endif
+ return ast_register_application_xml(app, noise_exec);
+}
+
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS, "White Noise Generator Application",
+ .load = load_module,
+ .unload = unload_module,
+ );
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