More on live mobile streaming

By Larry B, May 27, 2010

Our adventures in live mobile streaming continue. If anyone should happen to read this post on Thursday May 27, you can see the results of this effort at http://harvard.edu/commencement2010/

So what are the lessons learned so far? Here’s a preliminary list in no particular order:

  • Setting up the server side of things is the easiest part. Configuring for FMS delivery from Limelight, and for Wowza on Amazon EC2 was a breeze. Multiple bitrates, the RSS playlist for JW Player, the SMIL playlist for Wowza….once you figure out the moving parts, it works almost just like it’s supposed to.
  • Adaptive streaming from Limelight and other CDNs that use the ‘fcsubscribe’ method for load-balancing can cause a problem when switching to a streams that comes from a new edge node. More on this later…
  • Mobile devices: Make sure you’re encoding H.264 with Baseline profile level as low as you can go.  iPhones and iPads turned out to be the easiest to support fully.  Blackberries and Droids work…or they don’t. It seems to depend on the model phone, and on the network you’re on.  My personal Blackberry gets the RTSP stream just fine.  Others around the office with different Blackberries can’t play the stream. Same with Droids – some people are able to play it, some not. I haven’t discovered why just yet.  Codec issues are a likely possibility, but it’ll take some digging to find out. I have not found any useful documentation on the differences between Blackberry models, in terms of live video streaming support.
  • Encoders – this has been the headache of all headaches and took many many man-hours to get right.
    • Encoding three bitrates (100k, 500k, 1000k) to two different CDNs (Limelight, Wowza/EC2) takes a lot of horsepower.
    • One brand new 8-core Cisco machine with a brand new Osprey 240 proved unsuitable for capturing video at all.
    • Adobe Flash Media Live Encoder (FMLE) and Telestream Wirecast on Windows both depend on your display hardware and drivers. If you’re planning a headless encoding system, plan extra time to get it all working.
    • A 2-core IBM/Windows/Osprey system running FMLE gave us better encoding performance than an 8-core Mac Pro/AJA system running Wirecast.
    • All of the above systems had issues with audio/video sync, either being off from the start, or drifting as the webcast went on. Only on the Mac/AJA system were we able to resolve these in time for a successful webcast.
    • Ordinary desktop PC running consumer USB video capture devices are easiest to set up and are the machines most likely to work right off the bat.  No audio/video sync issues occurred with these, even though we were capturing video on one of a couple $50 USB
      devices and audio using the built-in audio support on the PC.  The more expensive and industrial-grade the hardware, the more trouble it gave us.
    • Our final encoding configuration included an 8-core MacPro/Wirecast for the 1Mbps and 500kbps streams, a single-core desktop PC running FMLE for the 100k streams, and a dual-core desktop PC with FMLE for capturing a 1.2Mbps H.264 archive file.
    • Some of our partner schools are using our infrastructure for mobile streaming. They’ve got Digital Rapids TouchStream appliances, and have had no encoding issues doing multiple bitrates from HD down to 3G/mobile. I’m quickly becoming a big fan of purpose-built appliances for encoding.

That’s about it for now…I’ll follow up on some of these as we do some analysis and learn more.

Dipping into Live Mobile Streaming

By Larry B, May 18, 2010

For an upcoming university commencement, I’ve been looking into doing live streaming in H.264/Flash, as well as http streaming to Apple iPhone/iPad/iPod devices (herein referred to as iP* devices) and rtsp streaming to Droids and Blackberrys. It’s been an experience piecing it all together, and I’ll be writing about some of the surprises and pitfalls as we figure out how to best do it.

In a nutshell, we’re using Limelight Networks’ Flash Media Server 3.5 for delivery to browsers on PCs and Macs. For mobile streaming, I provisioned and started up an instance of Wowza on Amazon EC2. One stream in (or several, for multiple bitrate support) via RTMP, and Wowza delivers in all the right formats – whether it’s chunked HTTP (Apple devices), RTSP (Droids and Blackberrys), or RTMP (Flash).  Setting that up involved an awful lot of moving parts, but half a day later, it was up and running and has been flawless in testing. We’ve been streaming multiple bitrates (100kbps, 500kbps, 900kbps) from Adobe Flash Media Live Encoder on a PC, as well as from Telestream Wirecast on a Mac.

We’ve developed a page that uses the JW Player (Flash) as the default, and falls back to HTML5 if it’s an iP* device, or provides an rtsp:// link if it’s a Droid or a Blackberry. Yes…Flash is the default for all browsers that will allow it, as it provides a uniform experience for all users, and a single thing to worry about from a user-support perspective.

What’s been interesting to me is how quickly it all went together. In a couple of days, starting with no deep mobile experience, we’ve provisioned infrastructure in the cloud, configured it, and are up and running with live Flash and mobile streaming for short money. More details to follow in the coming days…

New Hosting Provider – So Far, Excellence

By Larry B, May 18, 2010

There’s few things as delightful as being surprised by outstanding customer service and perfect execution of something difficult. Specifically, I’ve been wanting to move my website to a new hosting provider for a while now. My old host was becoming increasingly unreliable, particularly with respect to email. But the pain of switching hosts creates a powerful inertia – it’s easier, for a while, to deal with the problems than it is to move everything. I have a WordPress installation, MovableType, several busy email accounts using IMAP, a few databases, etc. I just didn’t have the time to deal with it.

GreenGeeks logoWhich leads to my experience with GreenGeeks hosting. I found them doing the usual Googling around and reading reviews. I liked the price. I liked the green idea of buying wind credits to offset power use (although how much of that represents a real net effect on the environment, I have no idea. It, at least, feels like doing something good.) I loved the idea that they will do your site migration for you.

I had absolutely no expectation that they would be able to migrate everything. I expected to spend some hours/days tweaking this and that to get it all up and running as on my original host. But just moving the files across and setting up users, etc….that’s helpful, anyway, right?

Well, it was perfect. There were a few emails as they asked questions and came to understand my environment, and then two days later I get an email that says “It’s ready.” And darned if it wasn’t. WordPress, MovableType, all my symlinks and apache config, all the email accounts with all the content intact. My migration effort consisted of updating my domain registrar’s DNS record. Period.

I can’t say much yet about reliability of the service (although it’s been 100% so far!), but I can say that the migration service and the general customer service I’ve received in my three days on GreenGeeks hosting has been outstanding. AFter starting to write this post I realized that they have an affiliate program, so yes, I signed up and these are affiliate links. But that was an afterthought. My enthusiasm for the service, and my delight at how easy it was to switch, is genuine.

Flash crossdomain security

By Larry B, May 2, 2010

Flash security constraints can prevent a SWF hosted on one domain from reading data hosted on another domain. Users trying out the SlideSync and SlideScroller plugins might encounter this issue if the XML data file that contains the slide URLs and timing is on a different website from the one that hosts the JW FLV Player itself.

The solution is to add a crossdomain.xml file to the root directory of the web server that hosts the XML file. There’s official Adobe docs on crossdomain policy files, and here’s a pretty good tutorial on crossdomain.xml files.

In short, you create this simple file using any text editor, and set up a rule describing which other sites may access data hosted on the site where the crossdomain.xml file lives.

<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM "http://www.adobe.com/xml/dtds/cross-domain-policy.dtd">
<cross-domain-policy>
   <allow-access-from domain="*.learningapi.com" />
</cross-domain-policy>

sbs!