Synchronized Slides for the JW FLV Player – Two New Plugins

By Larry B, April 6, 2010

SlideSync screenshotFor years I’ve been hearing and reading about demand for a simple synchronized slides plugin for the JW Flash Video player. Sure, you can do it with some Javascript: add event listeners to track the play-head position and use that to trigger image loads in a separate DIV. But that requires page scripting and introduces dependencies that might not always be do-able.

But I always thought there oughtta be a simpler way. So I made one. Honestly, I didn’t know if it was possible using the JW Plugin API, and while I’m a pretty good Java/Web programmer, I’m definitely not a Flash/ActionScript ace. So I decided to give it a try as a learning experience. The result is two plugins for the JW FLV Player: SlideSync and SlideScroller. These are free for commercial and non-commercial use.

You can see an example of the SlideSync and SlideScroller plugins in action, or look at documentation of the options and parameters, or go to Longtail Video’s plugin pages for the SlideSync and SlideScroller plugins.

There’s a lot of room for improvement and growth in this. It’s really a first-effort, but should be useful anyway in some cases. There are still reasons to use the Javascript event-listener model as well, which offers lots of flexibility and control you won’t get from the this plugin. But for simplicity, this is a good start. Feedback is welcome. Improvements welcome, too! The source is linked on the documentation page.

Dynamic Streaming & Stream Switching with Flash Video

By Larry B, March 26, 2010

My latest article, How to do Dynamic Streaming with Flash Media Server, has been published at There’s a page with code examples and demos of dynamic streaming on this site, as well.

I’d expected that writing this article was going to be an easy, quick process of explaining how to encode multiple files and set up a playlist in a couple of popular Flash video players (JW FLV Player 5.1 and Flowplayer 3.1.5). My problems started when I decided to actually test out the process as documented by Adobe and the player vendors by creating actual bandwidth fluctuations and watching the behavior of the player.

Imagine my surprise when things didn’t always work very well. I started to wonder if the dynamic streaming technology wasn’t really ready for prime-time. Some research led to finding and testing the 1080p player (from, which had simply outstanding switching performance – on the same videos from the same server. So the technology definitely works. [whew!]

After much research, talking to the vendors, and more testing, I came up with some guidelines that make things work pretty well in all the players. Still, there remains some room for improvement in the implementations of dynamic streaming in the popular players I tested, particularly when it comes to detecting bandwidth changes and then smoothly switching streams during playback.

Testing Adaptive Streaming by Controlling Bandwidth

By Larry B, March 17, 2010

In the course of researching my article on Dynamic Streaming in Flash, I ended up doing way more testing than I’d initially intended. But things didn’t work the way I expected right away, and being the way I am (foolish? glutton for punishment?), I had to find out why.

There’ll be more on that in the article when it comes out on, but for now, I wanted to make a note about how to simulate fluctuating bandwidth conditions.

On Windows, Netlimiter 3 Lite works OK, especially if you’re just doing bandwidth detection to select the appropriate stream at startup. Shunra VE Desktop seemed to create more realistic test conditions for fluctuating bandwidth and stream-switching during playback, an impression that was validated by colleagues I spoke with. At $850 a pop, it certainly ought to be better than the $20 NetLimiter.

But on the Mac, it all worked for free. It’s already built in to the OS’s Unix roots.  It’s in the ipfw command.  You set it up by creating filters with bandwidth limits, then associating those filters with the ports you want limited.  Here’s how to set up a bandwidth limiter for testing streaming over all ports. Note that if you’re not logged in as root, you will need to use sudo to run these:

sudo ipfw pipe 1 config bw 400kbps
sudo ipfw add 10 pipe 1 tcp from any to me
sudo ipfw add 11 pipe 1 tcp from any to me

Change it at will by issuing the pipe command again…

sudo ipfw pipe 1 config bw 1400kbps

Or remove the filters like this…

sudo ipfw delete 10
sudo ipfw delete 11

You can also introduce simulated network latency, control outbound bandwidth separately from inbound, and control bandwidth to or from a single IP address or subnet.  There’s great documentation at Luigi Rizzo’s Dummynet site.  Thanks also to Ask Bjorn Hansen for his mini-tutorial on this.

A Second Test of YouTube’s Captioning

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By Larry B, March 12, 2010

Audio quality being very important to the success of speech-recognition, I’ve re-recorded the video from my YouTube speech-recognition auto-captioning test. This time I used a high quality condenser mic plugged into a good mixer, and recorded in an acoustically good space.

With good quality audio, YouTube made a much better caption file. To be fair, in the beginning I throw around a few company names which aren’t real words, and I didn’t expect those to be right in the caption. But YouTube seems to be unable to recognize “YouTube”, which is kind of funny in its own way.

The other issue is the awful audio/video sync problem I’ve had recording direct from Webcam into YouTube. Oddly, I downloaded the video and corrected the problem using QT Sync. When I re-uploaded the corrected file to YouTube, the sync was off again.

Anyway, the captions are the interesting part. Here’s the clip:

YouTube Offers Speech-Recognition Captioning

By Larry B, March 5, 2010

It was only a matter of time. YouTube is bringing the speech recognition technology from Google Voice to bear on all the video in its vast library.

The industry has seen a variety of solutions for using speech-recognition to create a transcript of a video or podcast. Virage, Pictron, Streamsage, Podzinger all have done this. Only Pictron is more or less the same company it was at the start. Virage was acquired by Autonomy and has languished there as a Web product, Streamsage was acquired by Comcast and turned into an internal division, Podzinger has become Ramp…I’m not sure what they do, at this point, but it’s not the podcast transcription service they used to be. Virage and Streamsage go back almost ten years in this space, but their systems are still running in various enterprise and educational settings.

But back to YouTube… I use Google Voice, and the speech recognition is pretty good.  I rarely have to actually listen to a voice mail, since it shows up in my email as a text message that’s almost always easily decipherable, if not perfect. So just for fun, I tried YouTube’s captioning. Here’s the result.

Usually, speech-recognition provides a good set of words for searching, if nothing else. I’ve used speech-to-text to create searchable text from a video with very good results. It makes the video file, which is essentially opaque to a search engine, into something transparent. OK…in this case, maybe translucent.

I’m sure this would do better with better audio, and I will test that. In the meantime, YouTube does provide the means to download and edit the caption file, which is probably what this is best suited for, anyway. It’s a head start on a caption file, complete with time markers already in place. For those of us who are not professional transcriptionists, that has to beat making one from scratch.

Low-tech high-value instructional video

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By Larry B, March 4, 2010

Lots of us involved in instructional technology content development are rightly cognizant of high production values and a carefully edited script.  In my prior job as director of educational technology development at Harvard Business School, we were very focused on making highly-designed instructional products that looked great, sounded great, and didn’t waste a syllable in their tightly edited, word-crafted voiceover.

Nothing wrong with that, if that’s your target market and you’re planning to productize the content at a high price.  But there’s another way, as Jon Udell highlights in his conversation with Sal Khan, principal of Khan  Khan (interestingly, an MBA graduate of Harvard Business School) has created over one thousand instructional videos aimed primarily at middle/high school and college students on topics from Biology to Physics to Economics to Mathematics.

Khan uses nothing more complicated than a screen capture program like Camtasia, a Wacom tablet and a $20 headset to create powerful, explanatory tutorials that give the feel of looking-over-the-expert’s-shoulder.  Khan’s videos are posted to YouTube, which has granted khanacademy an exception to the ten-minute limit that applies to conventional YouTube channels.

What’s amazing is the scalability of this approach. Khan has been able to create this vast collection of material because he’s found the right combination for effective teaching while having a scalable process. You might think that reaching kids today means competing with video games, high-def TV, sophisticated animations and graphics by trying to beat those formats on their terms.  Khan’s gone the other way, and hit a home run, as evidenced by the popularity of his site and the feedback coming from kids, parents, and teachers.

There’s lots of rich detail in Jon’s interview with Sal on IT Conversations and it’s worth a listen (even if you don’t usually find podcast interviews compelling – this one is worth the download). Khan is working on analytics, assessment, and other innovation around the library of content he’s creating.

But at its heart, the lesson I see in this is that it’s not always about having the most advanced technology and picture-perfect production. Figuring out how to reach your audience and be effective, might mean going decidely low-tech.

Flash Video Performance on the Mac – Finally Some Real Data

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By Larry B, March 1, 2010

Is Flash video on a Mac a CPU hog?  More than on Windows? If so, why?

Thankfully, someone’s finally done a test to put some data behind the anecdotes.  (Doh!  Why I didn’t think of doing that?!?) Jan Ozer over at the Streaming Learning Center hastested Flash video vs. HTML5 video, covering all the browsers on both Windows and (Intel) Mac, and Flash versions 10.0 and (the new, performance-optimized) 10.1.

It’s hard to summarize the findings without leaving out important detail, so I recommend looking at Jan’s data directly.  The tables are revealing.  But in a nutshell, Jan found that where the video decoder can access hardware acceleration, performance is excellent, and where it can’t…not so much.  This means that on Windows, Flash is actually slightly more CPU-efficient than HTML5. On the Mac, where Apple has not made API hooks to its graphics hardware acceleration available to software developers, Flash and HTML5 are both hogs – unless you’re using HTML5 in Safari.  It suggests that Apple is using graphics acceleration APIs that it’s keeping from others who are developing applications for the Mac. (Kinda smells like what Microsoft was accused of years ago – keeping various Windows APIs secret so that its non-OS products would always have an advantage over  competitors. Microsoft has denied this. )  

Is it fair – or smart – to withhold powerful APIs from the devleopers who create the applications that make your computer useful and relevant to users?  At best. it’s disingenuous for Apple to criticize Adobe for Flash performance on the Mac while keeping access to hardware acceleration under wraps.  

In any case, Jan’s tests show that Adobe is continuing to work on this (to the extent that it can).  Video performance in Flash 10.1 is improved over 10.0 on both Mac and Windows. On Windows, the difference is dramatic.

Open Video and the “Flash Problem”

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By Larry B, February 26, 2010

Open Video Alliance LogoI had the distinct pleasure of attending Lawrence Lessig’s talk at Harvard Law School on behalf of the Open Video Alliance.  It was a terrific event, simulcast worldwide to dozens of screening locations using entirely open technologies; in particular, HTML5 and the Ogg Theora video codec.

Interesting side note that the session was funded in part by iCommons, the open standards/knowledge/software advocate; while I work at iCommons, Harvard University’s academic computing team.  I kept hearing “iCommons” mentioned, and it took a moment to recognize that it was another iCommons.  But I digress….

Lessig’s talk was great. The parts about open software, open standards, and the architecture (both legal and technical) of the read/write culture mirror closely the points in his books, and are eye-opening.  If you’ve not read Remix: Making Art and Commerce Thrive in the Hybrid Economy, you ought to.

But what I was really wondering about most during this talk was the open video concept and mention of the “Flash problem”.  Seems the Ogg Theora codec and HTML5 are seen as potential resolutions of a huge problem — the problem of proprietary video codecs and players. But as someone who builds, buys, deploys, and manages streaming video platforms and content, I couldn’t quite come to terms with all that I’d have to give up if I replaced the Flash Player in my solutions with HTML5 and Ogg.  Flash’s universality has been a tremendous boon to online video. Those of us who remember the format wars — Real vs Windows Media vs Quicktime, platform-specific plugins, single-platform codecs, browser incompatibilities — Flash is a breath of fresh air compared to that.  Being able to support a single set of APIs and codecs for all my users has been huge.  And, using a mature player such as the JW FLV Player,  being able to do stuff like:

  • support for rtmp or http streaming
  • callback event-based client-side scripting
  • playlist support (RSS, ATOM, XSPF)
  • bandwidth switching/adaptive streaming
  • plugins for screengrabs or stats collection
  • subtitles
  • control over buffering

I can create an outstanding user experience using these tools, and do it for more than the degenerate case of simply putting a video in the page.  All sorts of interactive behavior can be easily layered into my video apps, and with no browser dependencies to worry about.

Contrast that with my first experience showing HTML5 video to a non-techie, my wife.  At the end of Lessig talk, the Open Video Alliance announced the winners of the Open Video in 60 Seconds contest, which gave contributors 60 seconds to explain open video using video.  One of the entries, (not the winner, although IMHO it should have been) was by Rafaella, a teacher from Italy who did an outstanding job showing that all creativity is but a link in a long chain of the creative contributions of others.  I came home eager to show my wife, who I thought would really appreciate it.

At the conference, it was played in Quicktime with English subtitles. At home, I quickly found it on the Web, in the HTML5 player….with no subtitles.  Huh?  You gotta be kidding me!   Helpfully, a download link is provided to the .srt file containing the subtitles. That’s helpful. After all, of course I’d want to read this in an open texteditor alongside my video:

00:00:00,883 –> 00:00:02,485
I’m Raffaella.
Nice to meet you.

00:00:02,585 –> 00:00:04,982
I’m a teacher.
I make animations with kids.

Thankfully, a link was also provided to the original source site for the video, which offered a subtitled version, in… guessed it…Flash.

So….the Flash-based video world is seen as proprietary, which it is.  But as an applications guy, what makes a platform proprietary to me?  Vendor lock-in. Platform lock-in. Client-server dependencies.  I don’t really see this as a huge problem in Flash video.  I can deliver videos in Sorenson, On2, or MPEG4 codecs. I can use players by numerous vendors, or roll my own for free with the Flex SDK. I can serve video from any server, from FMS 3.5 to Apache to Wowza. I can switch from rtmp to http, or from Akamai to a free server under my desk. Or I can dump Flash and play the same MP4 content in Quicktime, RealPlayer, or Silverlight.  I’m not getting that proprietary locked-in feeling, really.

So what’s my point?  Not that Open Video is a bad idea….I think it’s wonderful. I love vendors with an open mindset and open products, like Kaltura.  Imagine when browser support for video approaches the support now universal for DOM scripting, Javascript, AJAX, etc. Powerful toolkits like JQuery and ExtJS are only possible because of the support for standards in the browser.  And, crucially, these toolkits have made it possible to do things in the browser that previously could only be done with Flash. There are some demos that show the promise of attractive, plugin-free Web video, although compatibility and functionality are still in a nascent stage.

But as a real working technologist solving problems on the ground every day, I don’t entirely understand the “Flash problem”.  I don’t want to employ closed technologies that narrow my options and lock me in, but I’m not seeing Flash as being that way very much when it comes to video.  But I’m eager to be educated.

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Streaming Flash Video With Amazon Cloudfront

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By Larry B, February 22, 2010

Since Amazon’s AWS is now supporting RTMP Flash streaming (on-demand only, so far) through its Cloudfront CDN, I thought it was time to write a quickstart guide for those who hadn’t tried it yet.

You’ll find How to Get Started with Amazon Cloudfront Streaming on The article walks through the steps for getting signed up and streaming in no time. A working example of the Cloudfront configuration created in the article is on this site at Flash Streaming With Amazon Cloudfront.

There’s lots of room for analysis of Cloudfront’s costs, performance, degree of control, and ease of use compared to other, more traditional CDNs.  This article doesn’t talk about any of that. What it covers is what you need to know to get signed up, get it configured, and start streaming.

Disrupting Class – Takeaways for Parents (and Instructional Technologists)

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By Larry B, February 10, 2010

Clay Christensen’s latest book, Disrupting Class: How Disruptive Innovation Will Change the Way the World Learns, applies the rules of Disruptive Innovation to the landscape of public K-12 education, and describes the ways in which the writing is already on the wall: public education as we know it will be transformed by application of computer-based instruction.  Boldly, Clay and his co-authors make a startling prediction: by 2019, 50% of high school courses will be delivered primarily online. That will require some changes and advances in instructional technology: authoring, scalability, instructional design, personalization, assessment. I’ll be following some of these advances and writing about them in the coming months. But the technology predictions are not the most startling thing in the book.

What’s most startling to me is their discussion of what researchers say is THE most important predictor of cognitive capacity in children.  The LENA Foundation sums up the findings of Todd Risley and Betty Hart succinctly:

  1. The variation in children’s IQs and language abilities is relative to the amount parents speak to their children.
  2. Children’s academic successes at ages nine and ten are attributable to the amount of talk they hear from birth to age three.
  3. Parents of advanced children talk significantly more to their children than parents of children who are not as advanced.

More importantly, the amount of talking that parents do to babies under one year in age, before they have demonstrated any meaningful language ability, is crucial.

The children whose parents did not begin speaking seriously to their children until their children could speak, at roughly age 12 months, suffered a persistent deficit in intellectual capacity, compared to those whose parents were talkative from the beginning.

Risely and Hart call it “language dancing” – ongoing, sophisticated speaking to a pre-talking baby – as distinct from “business talk” (“now roll over”, “do you want a bottle?”, and other more “utilitarian” talk). Again, from Disrupting Class (italics exactly as in the original):

One of the most important findings of the Risley-Hart study was that the level of income, ethnicity, and level of parents’ education had no explanatory power in determining the level of cognitive capacity that the children achieved. It is all explained by the amount of language dancing, or extra talk, over and above business talk, that the parents engaged in.  It accounted literally for all of the variance in outcomes.

I think we all knew that talking to kids is important, but showing that extra talking to babies this early has THE dominant effect on cognitive ability later in life is simply stunning.

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