Live Audio Broadcast with Wowza Media Server

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Live Audio Broadcast Using Wowza Media Server
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Wowza for Live Audio Broadcast A Brief
Overview

• Wowza Media Server is a popular, Java-based
  streaming server used for streaming live and
  on-demand audio and video content for consumption
  on various client platforms like PC, iPhone,
  Android, etc.
• Wowza provides a lot of features out of the box.
  Its written in Java and can be extended by
  writing components in Java
• In order to stream live radio, Neev uses a Flex
  based client that captures the audio input from
  users microphone and sends the same to Wowza
  Server for broadcasting
• This needs knowledge of Flex API and ActionScript
  
• For listening to the live stream, one can use
  JWPlayer (for Flash-based browsers) or HTML5 for
  iPhone/iPAD browsers

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Setting up Wowza Media Server

• Setting up Wowza Media Server comprises a few
  simple steps
• Assuming we have a Wowza Media Server already
  installed, we need to setup an application under
  Wowza Media Server. Lets call this liveradio.
• To do this
• Create a folder named liveradio under Wowza
  installations application directory
• Create a folder named liveradio under Wowza
  installations conf directory
• Create a file named Application.xml  by copying
  an existing file from conf directory
• Open the newly created Application.xml and modify
  the value of  /Root/Streams/StreamType node
  to live
• Restart Wowza server

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Coding the Flex Client for Broadcasting

• Coding the Flex Client for an audio broadcast
  would need very good understanding of Flex API
  and ActionScript (AS).
• You will need to setup an ActionScript project.  
• An IDE like FlashDevelop can be used for the
  same.  
• The typical steps you need to follow to capture
  audio and send to Wowza are given in the next few
  slides.

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Setting up the Microphone

• The screenshot below links to AS code for setting
  up the microphone.
• Please click on it to view it on the respective
  blog page.

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Setting up the Network Connection

• We need to set up the Network Connection to send
  captured audio data to Wowza server.
• (The screenshot below links to relevant code.
  Please click on it to view it.)

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Creating a Page for Playing to the Live
Broadcast

• The broadcasted audio can be played by using a
  flash based player or HTML5 audio-tag based on
  the browser.
• One can also use a player like JWPlayer that can
  embed audio/video in Flash format with HTML5
  fallback.
• Any other flv player that supports RTMP streaming
  can also be used.
• The code has two configurations viz RTMP and
  HTML5.
• RTMP is supported in browsers that allow content
  in flash.
• Since both iPhone and iPad do not support Flash
  content therefore one must fall back on HTML5 and
  use the Cupertino streaming support for iPAD and
  iPhone.
• (Please click on the code below to reach our blog
  which contains the code)

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Challenges and How They Were Overcome

• The streams published from the flex based client
  is in RTMP format and it can be streamed to a
  RTMP/Flash based player only
• SPEEX, which is the audio codec used, needs to be
  converted to an H.264 compatible codec like AAC .
  This can then be played on an iPhone/iPAD
• There are two ways to do the same
• Firstly, one could use an AddOn like Wowza
  Transcoder or a tool like FFMPEG
• The Wowza Transcoder works on only 64-bit
  machines with 64-bit Java, whereas FFMPEG is
  Open-Source and could be used on 32-bit machines

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Wowza Transcoder AddOn

• The Wowza Transcoder AddOn can transcode any
  configured incoming stream from one format to
  another.
• Here we encoded our live audio format codec
  from SPEEX to AAC.
• Heres how to do this
• Setup Wowza Transcoder AddOn. The AddOn works
  only on 64-bit machines.
• Create a transcoder template audio_speex.xml  in
  Wowzas transcoder/templates folder as shown in
  the linked content below. (Please click on it to
  reach the blog which contains the code)
• 3. Edit Application.xml and set /Root/Transcoder/T
  emplates to SourceStreamName_speex.xml,
  transrate.xml
• 4. The Wowza Transcoder Add-on is quite powerful
  and can transcode the incoming streams to
  multiple formats and bit rates for consumption on
  different types of players and devices with
  varying bandwidths.

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FFMPEG Simple Command Line Tool for
Transcoding

• FFmpeg is a set of tools to record, play and
  convert audio and video from/to various formats
• It can be used with Wowza Media Server to encode
  the live audio stream from our application
  from SPEEX to AAC codec
• Below are the steps to get it working with Wowza
• Install FFmpeg for the respective platform. This
  is a challenging task as FFmpeg has a lot of
  dependencies. It will usually get installed
  using yum on CentOS or aptitude get install on
  Ubuntu. Make sure FFmpeg is configured
  with enable-librtmp and enable-libfaac.
  Run ffmpeg command without any arguments if these
  are enabled.
• Start broadcasting the audio from the flex client
• Run the below command to transcode the live
  stream called audio from Wowza and make it
  available as another stream called audio_ios
  for playing on iPhone/iPADffmpeg -i
  rtmp///liveradio/audio -acodec libfaac -vcodec
  copy -f flv rtmp///liveradio/audio_ios

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Extending Current Setup to Include Video

• This setup can be extended easily to stream live
  video along with audio.
• This can be done as follows
• In your flex client, the Camera will be setup
  just like the Microphone was in the above
  example and the same will be attached to the
  flash NetStream
• The JWPlayer code is modified so that the
  provider for html2 is video instead of sound

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Wowza Use Cases at Neev

• We at Neev Technologies have successfully used
  Wowza Media Server for applications involving
  on-demand streaming of movies/TV programs, live
  audio/video streaming.
• In addition there are other use cases like live
  re-streaming/recording of IP camera streams, live
  video/chat where we see Wowza as a great fit.
• Some applications were deployed on a single node
  and some used Origin-Edge cluster for high load
  and scalability.
• Using the Java API we were also able to customize
  Wowza to add additional security features like
  time based expiry of stream URLs.
• Click here to read this blog post on the Neevtech
  blog.

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Partnerships
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