This change adds support to the JITTERBUFFER dialplan function for audio and video synchronization. When enabled the RTCP SR report is used to produce an NTP timestamp for both the audio and video streams. Using this information the video frames are queued until their NTP timestamp is equal to or behind the NTP timestamp of the audio. The audio jitterbuffer acts as the leader deciding when to shrink/grow the jitterbuffer when adaptive is in use. For both adaptive and fixed the video buffer follows the size of the audio jitterbuffer. ASTERISK-28533 Change-Id: I3fd75160426465e6d46bb2e198c07b9d314a4492
197 lines
6.4 KiB
C
197 lines
6.4 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2011, Digium, Inc.
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*
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* David Vossel <dvossel@digium.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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*
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* \brief Put a jitterbuffer on the read side of a channel
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*
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* \author David Vossel <dvossel@digium.com>
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*
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* \ingroup functions
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*/
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/*** MODULEINFO
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<support_level>core</support_level>
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***/
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#include "asterisk.h"
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#include "asterisk/module.h"
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#include "asterisk/channel.h"
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#include "asterisk/framehook.h"
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#include "asterisk/frame.h"
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#include "asterisk/pbx.h"
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#include "asterisk/abstract_jb.h"
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#include "asterisk/timing.h"
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#include "asterisk/app.h"
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/*** DOCUMENTATION
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<function name="JITTERBUFFER" language="en_US">
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<synopsis>
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Add a Jitterbuffer to the Read side of the channel. This dejitters the audio stream before it reaches the Asterisk core. This is a write only function.
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</synopsis>
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<syntax>
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<parameter name="jitterbuffer type" required="true">
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<optionlist>
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<option name="fixed">
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<para>Set a fixed jitterbuffer on the channel.</para>
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</option>
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<option name="adaptive">
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<para>Set an adaptive jitterbuffer on the channel.</para>
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</option>
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<option name="disabled">
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<para>Remove a previously set jitterbuffer from the channel.</para>
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</option>
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</optionlist>
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</parameter>
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</syntax>
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<description>
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<para>Jitterbuffers are constructed in two different ways.
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The first always take four arguments: <replaceable>max_size</replaceable>,
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<replaceable>resync_threshold</replaceable>, <replaceable>target_extra</replaceable>,
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and <replaceable>sync_video</replaceable>.
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Alternatively, a single argument of <literal>default</literal> can be provided,
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which will construct the default jitterbuffer for the given
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<replaceable>jitterbuffer type</replaceable>.</para>
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<para>The arguments are:</para>
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<para><replaceable>max_size</replaceable>: Length in milliseconds of the buffer.
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Defaults to 200 ms.</para>
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<para><replaceable>resync_threshold</replaceable>: The length in milliseconds over
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which a timestamp difference will result in resyncing the jitterbuffer.
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Defaults to 1000ms.</para>
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<para>target_extra: This option only affects the adaptive jitterbuffer. It represents
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the amount time in milliseconds by which the new jitter buffer will pad its size.
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Defaults to 40ms.</para>
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<para>sync_video: This option enables video synchronization with the audio stream. It can be
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turned on and off. Defaults to off.</para>
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<example title="Fixed with defaults" language="text">
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exten => 1,1,Set(JITTERBUFFER(fixed)=default)
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</example>
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<example title="Fixed with 200ms max size" language="text">
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exten => 1,1,Set(JITTERBUFFER(fixed)=200)
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</example>
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<example title="Fixed with 200ms max size and video sync support" language="text">
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exten => 1,1,Set(JITTERBUFFER(fixed)=200,,,yes)
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</example>
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<example title="Fixed with 200ms max size, resync threshold 1500" language="text">
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exten => 1,1,Set(JITTERBUFFER(fixed)=200,1500)
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</example>
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<example title="Adaptive with defaults" language="text">
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exten => 1,1,Set(JITTERBUFFER(adaptive)=default)
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</example>
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<example title="Adaptive with 200ms max size, 60ms target extra" language="text">
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exten => 1,1,Set(JITTERBUFFER(adaptive)=200,,60)
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</example>
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<example title="Adaptive with 200ms max size and video sync support" language="text">
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exten => 1,1,Set(JITTERBUFFER(adaptive)=200,,,yes)
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</example>
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<example title="Set a fixed jitterbuffer with defaults; then remove it" language="text">
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exten => 1,1,Set(JITTERBUFFER(fixed)=default)
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exten => 1,n,Set(JITTERBUFFER(disabled)=)
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</example>
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<note><para>If a channel specifies a jitterbuffer due to channel driver configuration and
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the JITTERBUFFER function has set a jitterbuffer for that channel, the jitterbuffer set by
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the JITTERBUFFER function will take priority and the jitterbuffer set by the channel
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configuration will not be applied.</para></note>
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</description>
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</function>
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***/
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static int jb_helper(struct ast_channel *chan, const char *cmd, char *data, const char *value)
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{
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struct ast_jb_conf jb_conf;
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if (!chan) {
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ast_log(LOG_WARNING, "No channel was provided to %s function.\n", cmd);
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return -1;
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}
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/* Initialize and set jb_conf */
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ast_jb_conf_default(&jb_conf);
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/* Now check user options to see if any of the defaults need to change. */
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if (!ast_strlen_zero(data)) {
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if (strcasecmp(data, "fixed") &&
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strcasecmp(data, "adaptive") &&
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strcasecmp(data, "disabled")) {
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ast_log(LOG_WARNING, "Unknown Jitterbuffer type %s. Failed to create jitterbuffer.\n", data);
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return -1;
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}
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ast_copy_string(jb_conf.impl, data, sizeof(jb_conf.impl));
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}
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if (!ast_strlen_zero(value) && strcasecmp(value, "default")) {
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char *parse = ast_strdupa(value);
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int res = 0;
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AST_DECLARE_APP_ARGS(args,
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AST_APP_ARG(max_size);
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AST_APP_ARG(resync_threshold);
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AST_APP_ARG(target_extra);
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AST_APP_ARG(sync_video);
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);
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AST_STANDARD_APP_ARGS(args, parse);
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if (!ast_strlen_zero(args.max_size)) {
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res |= ast_jb_read_conf(&jb_conf,
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"jbmaxsize",
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args.max_size);
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}
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if (!ast_strlen_zero(args.resync_threshold)) {
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res |= ast_jb_read_conf(&jb_conf,
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"jbresyncthreshold",
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args.resync_threshold);
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}
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if (!ast_strlen_zero(args.target_extra)) {
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res |= ast_jb_read_conf(&jb_conf,
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"jbtargetextra",
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args.target_extra);
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}
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if (!ast_strlen_zero(args.sync_video)) {
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res |= ast_jb_read_conf(&jb_conf,
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"jbsyncvideo",
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args.sync_video);
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}
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if (res) {
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ast_log(LOG_WARNING, "Invalid jitterbuffer parameters %s\n", value);
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}
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}
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ast_jb_create_framehook(chan, &jb_conf, 0);
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return 0;
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}
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static struct ast_custom_function jb_function = {
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.name = "JITTERBUFFER",
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.write = jb_helper,
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};
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static int unload_module(void)
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{
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return ast_custom_function_unregister(&jb_function);
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}
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static int load_module(void)
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{
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int res = ast_custom_function_register(&jb_function);
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return res ? AST_MODULE_LOAD_DECLINE : AST_MODULE_LOAD_SUCCESS;
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}
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AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Jitter buffer for read side of channel.");
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