Using a CDN Live service for adaptive and multi bitrate streaming

Introduction

Differences between adaptive and multi bitrate streaming

Both adaptive and multi bitrate streams are published through multiple (usually three) streams with the same content but in different bitrates (high quality, medium quality and low quality).

  • Adaptive Bitrate Streaming (ABR) - bitrate is adjusted automatically based on viewer's available bandwidth.
  • Multi Bitrate Streaming (MBR) - viewer can change bitrate using player's menu.

JW Player

The JW Player can be configured to support both adaptive and multi bitrate streaming together. JW Player is in adaptive bitrate mode when Auto is selected in player's menu and in addition viewer can change bitrate using the same menu.

Differences between adaptive and multi bitrate streaming

CDN Live service publishing

There are two types of CDN Live services - with Pull Publishing and with Push Publishing. Please refer to Differences between pull and push publishing for more details. In the following we will describe all necessary steps for both CDN Live service types.

Supported streaming protocols

In the following we will describe all necessary steps for RTMP and HLS protocols. Please refer to Supported CDN streaming protocols and formats for more details.

Create a CDN Live service with Pull or Push publishing

Please refer to Creating a CDN Live service for more details.

Publish to CDN Live service via Pull publishing (via your Wowza)

Set up your streaming server (Wowza) to publish through three different stream names. One stream name for each bitrate. Make sure that base URL (Origin URL) is always the same and only stream names are different as in the following example:

  • mystream_1 - 480 Kbps, 640x480 px
  • mystream_2 - 360 Kbps, 480x360 px
  • mystream_3 - 240 Kbps, 320x240 px
rtmp://yourwowza.com/path-to-stream/mystream_1
rtmp://yourwowza.com/path-to-stream/mystream_2
rtmp://yourwowza.com/path-to-stream/mystream_3

Please note that your origin live streams have to be published over RTMP protocol in MP4 or FLV container format and encoded with H.264 video codec and AAC or MP3 audio codec.

Publish to CDN Live service via Push publishing (via your Adobe FMLE)

Let's assume that your new CDN Live service with Push publishing has the following properties (Please refer to Services/How-To).

  • FMS URL - rtmp://6534287788.publishstream.cdnsun.net/P6534287788
  • Username - P6534287788
  • Password - Kmx7s14We

Set up your Adobe Flash Media Live Encoder (configured to multiple outputs)

  1. On the "Encoding Options" tab define your desired multiple bitrates as in the picture below.
    Adobe Flash Media Live Encoder multiple outputs
    If you plan to stream over HLS protocol then make sure that H.264 is selected as output format above.
  2. On the right hand side in your FMLE fill in your FMS URL rtmp://6534287788.publishstream.cdnsun.net/P6534287788 and choose your desired stream name (mystream in the picture below) followed by _%i as in the picture below.
    Adobe Flash Media Live Encoder multiple outputs
    Please note that %i is a wildcard for 1, 2, 3 as we have defined three outputs.
  3. Click on the "Connect" button and fill in your Username P6534287788 and Password Kmx7s14We as in the picture below.
    Adobe Flash Media Live Encoder authentication
  4. Finally click on the "OK" button.

Integrate into JW Player

Let's integrate your adaptive & multi bitrate CDN live stream via JW Player on your URL http://www.mycompany.com/index.html. Let's assume that 6534287788.r.cdnsun.net is the Service Identifier of your CDN Live service and that audio bitrate in all your three live streams is 32 Kbps.

Set CORS

Enable Cross Origin Resource Sharing (CORS) for .m3u8 files. Please refer here for more details.

Set cross-domain policy

Create a crossdomain.xml file and upload it on the URL http://www.mycompany.com/crossdomain.xml. Please refer here for more details.

Set Cache-Control for .m3u8 files

Set Cache-Control HTTP header value to no-cache for .m3u8 files. Please refer here for more details.

Set MIME type for .m3u8 files

Set MIME type to application/vnd.apple.mpegurl for .m3u8 files. Please refer here for more details.

RTMP protocol

Create a SMIL description file

Create a SMIL description file of your multiple bitrate live stream with the following content and upload it on your URL http://www.mycompany.com/multi.smil.

<smil>
<head>
<meta base="rtmp://6534287788.r.cdnsun.net/6534287788/_definst_" />
</head>
<body>
      <switch>
          <video src="mystream_1" width="640" height="480" system-bitrate="524288" />
          <video src="mystream_2" width="480" height="360" system-bitrate="401408" />
          <video src="mystream_3" width="320" height="240" system-bitrate="278528" />
      </switch>
</body>
</smil>

Please notice the difference between your (single bitrate) CDN RTMP URL

rtmp://6534287788.r.cdnsun.net/6534287788/_definst_/mystream

from the Services/How-To page and the RTMP URL above ("/mystream" at the end is missing). Also please ensure that all three "src", "width" and "height" attributes correspond to your settings in your Wowza or Adobe Flash Media Live Encoder. For "system-bitrate" please use the following formulae. 

system-bitrate = (audio + video bitrate in Kbps) * 1024

For example 278528 = (240 + 32) * 1024. Note that the "system-bitrate" has to be in 1024 base thus we really need to multiply by 1024 and not by 1000.

HLS protocol

Create an m3u8 description file

Create an m3u8 description file of your multiple bitrate live stream with the following content and upload it on your URL http://www.mycompany.com/multi.m3u8.

#EXTM3U
#EXT-X-VERSION:3
#EXT-X-ALLOW-CACHE:NO
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=512000,RESOLUTION=640x480
http://6534287788.r.cdnsun.net/6534287788/_definst_/mystream_1/chunklist_w1.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=392000,RESOLUTION=480x360
http://6534287788.r.cdnsun.net/6534287788/_definst_/mystream_2/chunklist_w2.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=272000,RESOLUTION=320x240
http://6534287788.r.cdnsun.net/6534287788/_definst_/mystream_3/chunklist_w3.m3u8

Please notice the difference between your (single bitrate) CDN HLS URL

http://6534287788.r.cdnsun.net/6534287788/_definst_/mystream/playlist.m3u8

from the Services/How-To page and the HLS URLs above. The chunklists must be in the format chunklist_wNUMBER.m3u8 where NUMBER is an integer between 1 and 9999999999. Additionally the NUMBERs must be unique within the file. It is also recommended to generate them randomly for every request (using PHP, Ruby, Python, etc.). Also please ensure that "width" and "height" attributes correspond to your settings in your Wowza or Adobe Flash Media Live Encoder. For "BANDWIDTH" please use the following formulae. 

BANDWIDTH = (audio + video bitrate in Kbps) * 1000

For example 272000 = (240 + 32) * 1024.

Use the SMIL and m3u8 files in JW Player

Add the following code to the page where you plan to embed JW Player (http://www.mycompany.com/index.html).

<script type="text/javascript" src="https://www.mycompany.com/jwplayer/8/30/jwplayer.js"></script>
<script>jwplayer.key="my_jwplayer_license_key";</script>

<div id="mediaplayer"></div>

<script type="text/javascript">
    jwplayer("mediaplayer").setup({
        'playlist': [{
             'sources': [
                {
                    'file': '/multi.smil'
                },
                {
                    'file': '/multi.m3u8'
                }
             ]
        }],                     
    });
</script>

That's all.

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