Streams of Thought: When HD Isn’t HD

This article first appeared in the December 2009/January 2010 issue of Streaming Media magazine. Click here for your free subscription.

HD on the web is not only hot, it’s the Holy Grail for those of us who have been pounding the HD streaming drum for years. I first started writing about this back in 2005, at a time when we were barely getting 750Kbps streams on the high end, and the full-screen versions of these streams still looked like bad cable-access content shoved through a meat grinder.

So anyone who claims to be pushing HD content across the web piques my interest. Unfortunately, as I’ve dug into the technical details and marketing claims, I’ve found that the definition of HD on the web is not the definition of HD on the television set.

On TV, there are clear definitions: 480p, 720p, and 1080i/p correspond to the vertical pixel sizes (a 1080i/p image is 1,920 pixels long by 1,080 pixels high). On the web, HD content is labeled as HD-quality content, which is to say it may not really be HD at all.

Case in point: During the rollout of its Akamai HD Network in late September, the CDN said it would be delivering content to the end user that was, in the words of Akamai president and CEO Paul Sagan, "Internet video that matches the television quality consumers are used to watching in their living rooms."

Except it’s not really up to the living room HD specification in terms of pixel size or bandwidth. And in some cases it originated as HD but is delivered at below standard definition quality. For some reason, CDNs seem to think they can create their own definition of HD that has nothing to do with the realities of television HD content.

Akamai’s HD content consists of content that starts as an HD source, is compressed down to 800Kbps, and is then delivered via HTTP/adaptive bitrate to any device that can receive this highly compressed content.

Think I’m making this up? Akamai’s co-founder and chief scientist, Tom Leighton, said during the Akamai HD Network rollout that there are "45 million iPhones out there today capable of displaying HD video."

When asked about this, Akamai first stated that the 45 million included all iPod touch units (only 33 million iPhones are expected to have been sold by the end of 2009) and then claimed that the iPhone’s 480x360 pixel screen—about a quarter of the size of a 720p screen—was receiving HD content because the content started as an HD source.

In reality, no iPhones or iPods on the market today display HD content. Many of them can almost receive standard definition content, as long as it is less than the 640x480 format we all call standard definition television.

I’d chalk it up to being misinformed or slick marketing, but Akamai’s not the first to make this claim.

Earlier in 2009, I did an article interview where a CDN customer told me that it was streaming in HD; when I probed, the customer said, "Well, we’re editing in HD on Final Cut," at which point the CDN representative interrupted and clarified. Like Akamai, it was starting with an HD source and was claiming HD delivery. Like Akamai, it was streaming to the iPhone and the desktop, but it certainly wasn’t streaming HD.

Finally, since Akamai is making the arbitrary claim of HD meeting the 800Kbps threshold, it can also make the claim that "the internet is ready for Akamai HD" as Tom Leighton did in the press conference. Of course it’s ready; most CDNs have been doing 800Kpbs streams for many years. No story here, please move along.

If I take Akamai’s argument about its definition of HD, I could pick an arbitrary number, say 200Kbps, and call it HD as long as that 200Kbps stream’s source came from my 1080p HD camera. Problem is, to match the living room television at 720p, you’d need at least 1.5Mbps–2Mbps of bandwidth per channel.

With multiple CDNs claiming to deliver HD on the most popular smartphone at superlow bitrates, the industry is telling a story that’s not sustainable. We’re doing a disservice to the producers and content owners who think their content is being streamed in HD, and who also believe that we can encode once in an industry standard (H.264) and stream that same file to every device (IPTVs, desktops, laptops, and mobile devices).

We’re also creating the potential for a huge backlash from the end user who looks at television HD content, compares it to our claims of HD delivery, and then tells friends that "this streaming thing isn’t ready for prime time."

Maybe we should just own up to what we’re really doing. "Yes, we can deliver HD 720p to your desktop at 1.5Mbps–2Mbps on a good day, but as for mobile, we take an HD stream and compress it down really far and deliver it to you at lower quality than the old standard-def TV that became obsolete earlier this year."

That would be truth in advertising.