Category Archives: webrtc Media Stack

Management of media plane in webRTC based communication. Involves media engine and codecs . Also deals with interactive webrtc media applications and streaming , recording etc .

continue : Streaming / broadcasting Live Video call to non webrtc supported browsers and media players

This blog is in continuation to the attempts / outcomes and problems in building a WebRTC to RTP media framework that successfully stream / broadcast WebRTC content to non webrtc supported browsers ( safari / IE ) / media players ( VLC )


Attempt 4: Stream the content to a WebRTC endpoint which is hidden in a video call . Pick the stream from vp8 object URL send to a streaming server

This process involved the following components :

  • WebRTC API : simplewebrtc on Chrome
  • Transfer mechanism from client to Streaming server:  webrtc media channel

Problems : No streaming server is qualified to handle a direct webrtc input and stream it on network .


Attempt 4.1 : Stream the content to a WebRTC endpoint . Do WebRTC Endpoint to RTP Endpoint bridge using Kurento APIs. 

Use the RTP port and ip address to input into a ffmpeg or gstreamer or VLC terminal command and out put a live H264 stream on another ip and port address .  

This process involved the following components :

  • API : Kurento
  • Transfer mechanism : HTML5 webrtc client -> application server hosting java -> media server -> application for webrtc media to RTP media conversation -> RTP player

Screenshots of attempts with Wowza to stream from a ip and port

kurentowowoza

problems :

  • The stream was black ie no video content .

Attempt 4.2 : Build a WebRTC Endpoint to Http endpoint in kurento and force the video audio encoding to be that of H264 and PCMU.

code for adding constraints to output media and forcing choice of codecs

MediaPipeline pipeline = kurento.createMediaPipeline();
    WebRtcEndpoint webRtcEndpoint = new WebRtcEndpoint.Builder(pipeline).build();
    HttpGetEndpoint httpEndpoint=new HttpGetEndpoint.Builder(pipeline).build();

    org.kurento.client.Fraction fr= new org.kurento.client.Fraction(1, 30);         
    VideoCaps vc= new VideoCaps(VideoCodec.H264,fr);
    httpEndpoint.setVideoFormat(vc);

    AudioCaps ac= new AudioCaps(AudioCodec.PCMU, 65536);
    httpEndpoint.setAudioFormat(ac);

    webRtcEndpoint.connect(httpEndpoint);

code for using gstreamer filter to force the output in raw format . It is a alternate solution to above

//basic media operation of 1 pipeline and 2 endpoinst
MediaPipeline pipeline = kurento.createMediaPipeline();
WebRtcEndpoint webRtcEndpoint = new WebRtcEndpoint.Builder(pipeline).build();
RtpEndpoint rtpEndpoint = new RtpEndpoint.Builder(pipeline).build();

//adding Gstream filters 
GStreamerFilter filter1 = new GStreamerFilter.Builder(pipeline, "videorate max-rate=30").withFilterType(FilterType.VIDEO).build();
GStreamerFilter filter2 = new GStreamerFilter.Builder(pipeline, "capsfilter caps=video/x-h264,width=1280,height=720,framerate=30/1").withFilterType(FilterType.VIDEO).build();
GStreamerFilter filter3 = new GStreamerFilter.Builder(pipeline, "capsfilter caps=audio/x-mpeg,layer=3,rate=48000").withFilterType(FilterType.AUDIO).build();

//connecting all poin ts to one another 
webRtcEndpoint.connect (filter1); 
filter1.connect (filter2); 
filter2.connect (filter3); 
filter3.connect (rtpEndpoint);

// RTP SDP offer and answer
String requestRTPsdp = rtpEndpoint.generateOffer();
rtpEndpoint.processAnswer(requestRTPsdp);

problem : The output is still webm


Attempt 5  : Use a RTP SDP Endpoint ( ie a SDP file valid for a given session ) and use it to play the WebRTC media over Wowza streaming server

This process involved the following components

  1. WebRTC Stream and object URL of the blob containing VP8 media
  2. Kurento  WebRTC Endpoint  bridge to generate SDP
  3. Wowza Streaming server

code for kurento to generate a SDP file from WebRTC to RTP bridge

@RequestMapping(value = "/rtpsdp", method = RequestMethod.POST)
private String processRequestrtpsdp(@RequestBody String sdpOffer)
throws IOException, URISyntaxException, InterruptedException {

//basic media operation of 1 pipeline and 2 endpoinst
MediaPipeline pipeline = kurento.createMediaPipeline();
WebRtcEndpoint webRtcEndpoint = new WebRtcEndpoint.Builder(pipeline).build();
RtpEndpoint rtpEndpoint = new RtpEndpoint.Builder(pipeline).build();

//connecting all poin ts to one another 
webRtcEndpoint.connect (rtpEndpoint);

// RTP SDP offer and answer
String requestRTPsdp = rtpEndpoint.generateOffer();
rtpEndpoint.processAnswer(requestRTPsdp);

// write the SDP conector to an external file
PrintWriter out = new PrintWriter("/tmp/test.sdp");
out.println(requestRTPsdp);
out.close();

HttpGetEndpoint httpEndpoint = new HttpGetEndpoint.Builder(pipeline).build();
PlayerEndpoint player = new PlayerEndpoint.Builder(pipeline, requestRTPsdp).build();
httpEndpoint.connect(rtpEndpoint);
player.connect(httpEndpoint);

// Playing media and opening the default desktop browser
player.play();
String videoUrl = httpEndpoint.getUrl();
System.out.println(" ------- video URL -------------"+ videoUrl);

// send the response to front client
String responseSdp = webRtcEndpoint.processOffer(sdpOffer);

return responseSdp;
}

problems : wowza doesnt not recognize the WebRTC SDP and play the video

screenshot of wowza with SDP input

Screenshot from 2015-01-30 15:28:59


Attempt 5.1 : Use a RTP SDP Endpoint ( ie a SDP file valid for a given session ) and use it to play the WebRTC media over Default Ubuntu media player 

SDP file formed contains contents such as :

v=0
o=- 3631611195 3631611195 IN IP4 192.168.0.119
s=Kurento Media Server
c=IN IP4 192.168.0.119
t=0 0
m=audio 42802 RTP/AVP 98 99 0
a=rtpmap:98 OPUS/48000/2
a=rtpmap:99 AMR/8000/1
a=rtpmap:0 PCMU/8000
a=ssrc:2713728673 cname:user59375791@host-ad1117df
m=video 35946 RTP/AVP 96 97 100 101
a=rtpmap:96 H263-1998/90000
a=rtpmap:97 VP8/90000
a=rtpmap:100 MP4V-ES/90000
a=rtpmap:101 H264/90000
a=ssrc:93449274 cname:user59375791@host-ad1117df

problem : deformed media

screenshot of playing from a SDP file

Screenshot from 2015-01-29 17:42:21


Attempt 5.2 : Use a RTP SDP Endpoint ( ie a SDP file valid for a given session ) and use it to play the WebRTC media over VLC using socket input

problem : nothing plays

screenshot of VLC connected to play from socket and failure to play anything

Screenshot from 2015-01-21 17:49:52

Attempt 5.3: Create a WebRTC endpoint and connected it to RTP endpoint via media pipelines . Also make the RTP SDP offer and answering the same . Play with ffnpeg / ffplay / gst playbin

String requestRTPsdp = rtpEndpoint.generateOffer();
rtpEndpoint.processAnswer(requestRTPsdp);

Write the requestRTPsdp to a file and obtain a RTP connector endpoint with Application/SDP .It plays okay with gst playbin ( 10 secs without audio )

Successful attempt to play from a gst playbin

gst-launch -vvv playbin uri=file:///tmp/test.sdp 

donekurento streaming

but refuses to be played by VLC , ffplay and even wowza . The error generated with

ffmpeg -i test.sdp -vcodec copy -acodec copy -f mpegts output-file.ts

or

ffmpeg -re -i test.sdp -vcodec h264 -acodec mp3 -f mpegts “udp://192.168.4.26:5000”

are

Could not find codec parameter for stream1 ( video:h263, none ) .Other errors types are , Could not write header for output file output file is empty nothing was encoded

Error screenshots of trying to play the RTP SDP file with ffmpeg

ffmpeg error kurebto1 ffmpeg error kurebto2


Attempt 6 : Use a WebRTC capable media and streaming server ( eg Kurento )  to pick a live stream of VP8 . Convert the VP8 to H268  ( ffmpeg / RTP endpoint ) . Convert H268 to Mp4 using MP4 parser and pass to a streaming server  ( wowza)

In process . to be updated .

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Streaming / broadcasting Live Video call to non webrtc supported browsers and media players

As the title of this article suggests I am going to pen my attempts of streaming / broadcasting Live Video WebRTC call to non WebRTC supported browsers and media players such as VLC , ffplay , default video player in Linux etc .

I am currently attempting to do this by making my own MP4 engine from WebRTC feed . However I am sharing my past experiments in hope of helping someone whose objective is not the same as mine and might get some help from these threads .


Attempt 1 : use one to many brodcasting API :

<!DOCTYPE html>
<html id=”home” lang=”en”>

<head>
<meta http-equiv=”Content-Type” content=”text/html; charset=UTF-8″>
<meta charset=utf-8>
<meta name=”viewport” content=”width=device-width, initial-scale=1.0, user-scalable=no”>
<meta name=”author” content=”altanai”>
<meta http-equiv=”X-UA-Compatible” content=”IE=edge,chrome=1″>

<link rel=”stylesheet” type=”text/css” href=”style.css”>

</head>

<body>

<table class=”visible”>
<tr>
<td style=”text-align: right;”>
<input type=”text” id=”conference-name” placeholder=”Broadcast Name”>
</td>
<td>
<select id=”broadcasting-option”>
<option>Audio + Video</option>
<option>Only Audio</option>
<option>Screen</option>
</select>
</td>
<td>
<button id=”start-conferencing”>Start Broadcasting</button>
</td>
</tr>
</table>
<table id=”rooms-list” class=”visible”></table>

<div id=”participants”></div>

<script src=”RTCPeerConnection-v1.5.js”></script>
<script src=”firebase.js”></script>
<script src=”broadcast.js”></script>
<script src=”broadcast-ui.js”></script>

</body>

</html>
 

It uses API fromwebrtc-experiment.com. The broadcast is in one direction only where the viewrs are never asked for their mic / webcam permission .

problem : The broadcast is for WebRTC browsers only and doesnt support non webrtc players / browsers


Attempt 1.1: Stream the media directly to nodejs through websocket


window.addEventListener('DOMContentLoaded', function() {

var v = document.getElementById('v');
navigator.getUserMedia = (navigator.getUserMedia || 
navigator.webkitGetUserMedia || 
navigator.mozGetUserMedia || 
navigator.msGetUserMedia);

if (navigator.getUserMedia) {
// Request access to video only
navigator.getUserMedia(
{
video:true,
audio:false
}, 
function(stream) {
var url = window.URL || window.webkitURL;
v.src = url ? url.createObjectURL(stream) : stream;
v.play();

var ws = new WebSocket('ws://localhost:3000', 'echo-protocol');
waitForSocketConnection(ws, function(){

console.log(" url.createObjectURL(stream)-----", url.createObjectURL(stream))
ws.send(stream);

console.log("message sent!!!"); 
});

},
function(error) {
alert('Something went wrong. (error code ' + error.code + ')');
return;
}
);
}
else {
alert('Sorry, the browser you are using doesn\'t support getUserMedia');
return;
}
});

//Make the function wait until the connection is made...
function waitForSocketConnection(socket, callback){
setTimeout(
function () {
if (socket.readyState === 1) {
console.log("Connection is made")
if(callback != null){
callback();
}
return;

} else {
console.log("wait for connection...")
waitForSocketConnection(socket, callback);
}

}, 5); // wait 5 milisecond for the connection...
}

problem : The video is in form of buffer and doesnot play


Attempt 2: Record the WebRTC media ( 5 secs each ) into chunks of webm format->  transfer them to other end -> append the chunks together like a regular file 

This process involved the following components :

  • Recorder Javascript library : RecordJs
  • Transfer mechanism : Record using RecordRTC.js -> send to other end for media server -> stitching together the small webm files into big one at runtime and play
  • Programs :

Code for video recorder

navigator.getUserMedia(videoConstraints, function(stream) {

video.onloadedmetadata = function() {
video.width = 320;
video.height = 240;

var options = {
type: isRecordVideo ? 'video' : 'gif',
video: video,
canvas: {
width: canvasWidth_input.value,
height: canvasHeight_input.value
}
};

recorder = window.RecordRTC(stream, options);
recorder.startRecording();
};
video.src = URL.createObjectURL(stream);
}, function() {
if (document.getElementById('record-screen').checked) {
if (location.protocol === 'http:')
alert('&lt;https&gt; is mandatory to capture screen.');
else
alert('Multi-capturing of screen is not allowed. Capturing process is denied. Are you enabled flag: "Enable screen capture support in getUserMedia"?');
} else
alert('Webcam access is denied.');
});

Code for video append-er

var FILE1 = '1.webm';
var FILE2 = '2.webm';
var FILE3 = '3.webm';
var FILE4 = '4.webm';
var FILE5 = '5.webm';

var NUM_CHUNKS = 5;
var video = document.querySelector('video');

window.MediaSource = window.MediaSource || window.WebKitMediaSource;
if (!!!window.MediaSource) {
alert('MediaSource API is not available');
}

var mediaSource = new MediaSource();

video.src = window.URL.createObjectURL(mediaSource);

function callback(e) {

var sourceBuffer = mediaSource.addSourceBuffer('video/webm; codecs="vorbis,vp8"');

GET(FILE1, function(uInt8Array) {

var file = new Blob([uInt8Array], {type: 'video/webm'});
var i = 1;

(function readChunk_(i) {

var reader = new FileReader();

reader.onload = function(e) {

sourceBuffer.appendBuffer(new Uint8Array(e.target.result));

if (i == NUM_CHUNKS) mediaSource.endOfStream();

else {
if (video.paused) {
video.play(); // Start playing after 1st chunk is appended.
}
readChunk_(++i);
}

};

reader.readAsArrayBuffer(file);

})(i); // Start the recursive call by self calling.
});
}

mediaSource.addEventListener('sourceopen', callback, false);
mediaSource.addEventListener('webkitsourceopen', callback, false);
mediaSource.addEventListener('webkitsourceended', function(e) {
logger.log('mediaSource readyState: ' + this.readyState);
}, false);

// function get the video via XHR
function GET(url, callback) {

var xhr = new XMLHttpRequest();
xhr.open('GET', url, true);
xhr.responseType = 'arraybuffer';
xhr.send();

xhr.onload = function(e) {

if (xhr.status != 200) {
alert("Unexpected status code " + xhr.status + " for " + url);
return false;
}

callback(new Uint8Array(xhr.response));
};
}

Shortcoming of this approach

  1. The webm files failed to play on most of the media players
  2. The recorder can only either record video or audio file at a time .

Attempt 2.1: Record the WebRTC media ( 5 secs each ) into chunks of webm format ( RecordRTC.js) >  Use Kurento JS script ( kws-media-api,js) to make a HTTP Endpoint to recorded Webm files  -> append the chunks together like a regular file at runtime 


function getByID(id) {
return document.getElementById(id);
}

var recordAudio = getByID('record-audio'),
recordVideo = getByID('record-video'),
stopRecordingAudio = getByID('stop-recording-audio'),
stopRecordingVideo = getByID('stop-recording-video'),
broadcasting=getByID('broadcasting');

var canvasWidth_input = getByID('canvas-width-input'),
canvasHeight_input = getByID('canvas-height-input');

var video = getByID('video');
var audio = getByID('audio');

var videoConstraints = {
audio: false,
video: {
mandatory: {},
optional: []
}
};

var audioConstraints = {
audio: true,
video: false
};

const ws_uri = 'ws://localhost:8888/kurento';
var URL_SMALL="http://localhost:8080/streamtomp4/approach1/5561840332.webm";


var audioStream;
var recorder;

recordAudio.onclick = function() {
if (!audioStream)
navigator.getUserMedia(audioConstraints, function(stream) {

if (window.IsChrome) stream = new window.MediaStream(stream.getAudioTracks());
audioStream = stream;

audio.src = URL.createObjectURL(audioStream);
audio.muted = true;
audio.play();

// "audio" is a default type
recorder = window.RecordRTC(stream, {
type: 'audio'
});
recorder.startRecording();
}, function() {});
else {
audio.src = URL.createObjectURL(audioStream);
audio.muted = true;
audio.play();
if (recorder) recorder.startRecording();
}


window.isAudio = true;

this.disabled = true;
stopRecordingAudio.disabled = false;
};

stopRecordingAudio.onclick = function() {
this.disabled = true;
recordAudio.disabled = false;
audio.src = '';

if (recorder)
recorder.stopRecording(function(url) {
audio.src = url;
audio.muted = false;
audio.play();

document.getElementById('audio-url-preview').innerHTML = '&lt;a href="' + url + '" target="_blank"&gt;Recorded Audio URL&lt;/a&gt;';
});
};

recordVideo.onclick = function() {
recordVideoOrGIF(true);
};


function recordVideoOrGIF(isRecordVideo) {
navigator.getUserMedia(videoConstraints, function(stream) {

video.onloadedmetadata = function() {
video.width = 320;
video.height = 240;

var options = {
type: isRecordVideo ? 'video' : 'gif',
video: video,
canvas: {
width: canvasWidth_input.value,
height: canvasHeight_input.value
}
};

recorder = window.RecordRTC(stream, options);
recorder.startRecording();
};
video.src = URL.createObjectURL(stream);
}, function() {
if (document.getElementById('record-screen').checked) {
if (location.protocol === 'http:')
alert('&lt;https&gt; is mandatory to capture screen.');
else
alert('Multi-capturing of screen is not allowed. Capturing process is denied. Are you enabled flag: "Enable screen capture support in getUserMedia"?');
} else
alert('Webcam access is denied.');
});

window.isAudio = false;

if (isRecordVideo) {
recordVideo.disabled = true;
stopRecordingVideo.disabled = false;
} else {
recordGIF.disabled = true;
stopRecordingGIF.disabled = false;
}
}

stopRecordingVideo.onclick = function() {
this.disabled = true;
recordVideo.disabled = false;

if (recorder)
recorder.stopRecording(function(url) {
video.src = url;
video.play();
document.getElementById('video-url-preview').innerHTML = '&lt;a href="' + url + '" target="_blank"&gt;Recorded Video URL&lt;/a&gt;';

});
};


/*--------------------------broadcasting -----------------------------------*/

function onerror(error)
{
console.log( " error occured");
console.error(error);
};

broadcast.onclick = function() {
var videoOutput = document.getElementById("videoOutput");

KwsMedia(ws_uri, function(error, kwsMedia)
{
if(error) return onerror(error);

// Create pipeline
kwsMedia.create('MediaPipeline', function(error, pipeline)
{
if(error) return onerror(error);

// Create pipeline media elements (endpoints &amp; filters)
pipeline.create('PlayerEndpoint', {uri: URL_SMALL},
function(error, player)
{
if(error) return console.error(error);

pipeline.create('HttpGetEndpoint', function(error, httpGet)
{
if(error) return onerror(error);

// Connect media element between them
player.connect(httpGet, function(error, pipeline)
{
if(error) return onerror(error);
// Set the video on the video tag
httpGet.getUrl(function(error, url)
{
if(error) return onerror(error);

videoOutput.src = url;

console.log(url);

// Start player
player.play(function(error)
{
if(error) return onerror(error);

console.log('player.play');
});
});
});

// Subscribe to HttpGetEndpoint EOS event
httpGet.on('EndOfStream', function(event)
{
console.log("EndOfStream event:", event);
});
});
});
});
},
onerror);

}

problem : dissecting the live video into small the files and appending to each other on reception is an expensive , time and resource consuming process . Also involves heavy buffering and other problems pertaining to real-time streaming .


Attempt 2.2 : Send the recorded chunks of webm to a port on linux server . Use socket programming to pick up these individual files and play using  VLC player from UDP port of the Linux Server

Screenshot from 2015-01-22 15:32:51


Attempt 2.3: Send the recorded chunks of webm to a port on linux server socket . Use socket programming to pick up these individual webm files and convert to H264 format so that they can be send to a media server. 

This process involved the following components :

  • Recorder Javascript library : RecordJs
  • Transfer mechanism :WebRTC endpoint -> Call handler ( Record in chunks ) -> ffmpeg / gstreamer to put it on RTP -> streaming server like wowza – > viewers
  • Programs : Use HTML webpage Webscoket connection -> nodejs program to write content from websocket to linux socket -> nodejs program to read that socket and print the content on console

Program to transfer the webm recorder files over websocket to nodejs program

//Make the function wait until the connection is made...
function waitForSocketConnection(socket, callback){
setTimeout(
function () {
if (socket.readyState === 1) {
console.log("Connection is made")
if(callback != null){
callback();
}
return;

} else {
console.log("wait for connection...")
waitForSocketConnection(socket, callback);
}

}, 5); // wait 5 milisecond for the connection...
}

function previewFile() {
var preview = document.querySelector('img');
var file = document.querySelector('input[type=file]').files[0];
var reader = new FileReader();

reader.onloadend = function () {

preview.src = reader.result;
console.log(" reader result ", reader.result);

var video=document.getElementById("v");
video.src=reader.result;
console.log(" video played ");

var ws = new WebSocket('ws://localhost:3000', 'echo-protocol');

waitForSocketConnection(ws, function(){
ws.send(reader.result); 
console.log("message sent!!!"); 
});

}

if (file) {
// converts to base64 encoded string of the file data
//reader.readAsDataURL(file);

reader.readAsBinaryString(file);

} else {
preview.src = "";
}
}

Program for Linux Sockets sender which creates the socket for the webm files

var net = require('net');
var fs = require('fs');
var socketPath = '/tmp/tfxsocket';
var http = require('http');
var stream = require('stream');
var util = require('util');

var WebSocketServer = require('ws').Server;
var port = 3000;
var serverUrl = "localhost";

var socket;
/*--------------------------------http server -----------------------------*/
var server= http.createServer(function (request, response) {

});

server.listen(port, serverUrl);

console.log('HTTP Server running at ',serverUrl,port);

/*--------------------------------websocket server -----------------------------*/

var wss = new WebSocketServer({server: server});

wss.on("connection", function(ws) {
console.log("websocket connection open");

ws.on('message', function (message) {
console.log(" stream recived from broadcast client on port 3000 ");

var s = require('net').Socket();
s.connect(socketPath);
s.write(message);

console.log(" send the stream to socketPath",socketPath); 
});

ws.on("close", function() {
console.log("websocket connection close")
});

});

Program for Linux Socket Listener using nodejs and socket . Here the socket is in node /tmp/mysocket

var net = require('net');

var client = net.createConnection("/tmp/mysocket");

client.on("connect", function() {
console.log("connected to mysocket");
});

client.on("data", function(data) {
console.log(data);
});

client.on('end', function() {
console.log('server disconnected');
});

Output 1: Video Buffer displayed

Screenshot from 2015-01-22 15:35:06 (copy)

Output 2 : Random data from Video displayed

Screenshot from 2015-01-23 12:57:35

ffmpeg format of transfering the content from socket to UDP IP and port

ffmpeg -i unix://tmp/mysocket -f format udp://192.168.0.119:8083

problems of this approach : The video was on a passing stage from the socket and contained no information as such when tried to play / show console


Attempt 3 : Send the live WebRTC stream from Kurento WebRTC endpoint to Kurento HTTP endpoint . play using  Mozilla VLC web plugin

VLC mozilla plugin can be embedded by :


name=”video2″
autoplay=”yes” loop=”no” hidden=”no”
target=”rtp://@192.165.0.119:8086″ />

screenshot of failure on part of Mozilla VLC plugin to play from a WebRTC endpoint

Screenshot from 2015-01-29 10:37:06Screenshot from 2015-01-29 10:37:17

Screenshot from 2015-01-29 12:06:14

problem : VLC mozilla plugin was unable to play the video

………………………………………………………………………………………………………………..

The 4th , 5th and 6th sections of this article are in the next blog :

continue : Streaming / broadcasting Live Video call to non webrtc supported browsers and media players

WebRTC Media Streams

—SDP signaling and negotiation for media plane

—Media plane adaptation is done at the SBC for network carried media, —Media plane adaptation/support should be done for all network hosted media services which face peer-to-peer media clients —SBC is utilized to enhance compatibility by modifying SDP contents as necessary and engaging appropriate media servers or transcoding resources. —The high-level architecture elements of WebRTC media streams can be divided into two areas:

—Adaptation of WebRTC Media Plane to IMS Media Plane

—General  – oEncryption, RTP Multiplexing, Support for ICE —Audio -oInterworking of differing WebRTC and codec sets —Video -o Use of VP8  o Support for H.264 —Data -oSupport of MSRP ( RCS standard for messaging over DataChannel API)

—Peer-to-Peer Media

—Direct connection to media servers and media gateways ……………………… —Use common codec set wherever possible to eliminate transcoding —Use regionalized transcoding where common codec not available Note: Real-time video transcoding is expensive and performance impacting —On-going standards/device/network work needs to be done to expand common codec set. —WebRTC codec standards have not been finalized yet. WebRTC target is to support royalty free codecs within its standards. —

Media WebRTC legacy
Audio G.711, Opus G.711, AMR, AMR-WB (G.722.2)
Audio – Extended G.729a[b], G.726
Video VP8 H.264/AVC

—Supporting common codecs between VoLTE devices and WebRTC endpoints requires one or more of the following: 1.Support of WebRTC codecs on 3GPP/GSMA 2.Support of 3GPP/GSMA codecs on WebRTC 3.WebRTC browser support of codecs native to the device