HD web video

28
Jul/094

High definition video or HD video as it is known, is digital video with higher resolution than the previous standards (i.e. SD video and DVD). This high resolution is achieved through new video file formats, which allow new codecs, certain performance optimizations (like deblocking) and a lot higher bandwidth(bitrate).

HD resolutions are noted with the number of lines and if it is progressive or interlaced stream. Thus 540p for instance means – resolution 960 x 540 pixels (assuming 16:9 aspect ratio) and progressive stream. Note that interlaced streams are primarily available for compliance with older standards like DVD.

Full HD resolution (HDTV) means 1080p which is a resolution of 1920×1080 pixels. The most sought after (and practical from PC point of view) HD video resolution is 768p (1280 x 768).

HD video for personal appliances

For hardware appliances(and PC’s) HD video imposes two main technical problems that as of now(2009) are pretty much solvable:

First was the storage capacity needed to store the huge video files. Personal Storage now is cheap and huge in space.
Second was the processing power involved in playing the video. Since there is much more data to be read and interpreted in realtime this was a problem for yesterday’s hardware, but now there are specialized digital processors(DSP/GPU) that have acceleration for some standartized operations like some H.264 codec functions used in .WMV and .MP4 files.

HD video on the web

Now on the web there is a slightly different story… Most of the video on the web today is with DVD(640×480) or lower resolution and the bitrate used is usually bellow 600kbps. HD is bigger… a lot bigger.

Now when I say that HD is a lot bigger it is not clear to most people how exactly bigger it actually is. So let me explain…

1080p(1920×1080) compared to DVD(640×480) is precisely 6.75 times bigger image “area” which means that if we used the same compression and bitrate allocation as used in DVD you would need 7DVD’s to store a single video title.

If we assume that a 600kbps stream can deliver a “feasible” quality video with DVD resolution in order to achieve the same level of quality with a 1080p resolution stream we will need at least 4mbps. Now since this level of quality in the above example I used the word “feasible” for, is about the lowest possible sensible bitrate setting we will need a lot more bandwidth to get to the “professional” level.

Let’s get back to the web now. When you publish video to the web you usually do it with the intention to show this video to other remote people and usually many of them.

There are three major problems to stream high definition video to web viewers:

The problem with increased costs. There are three components to this – storage space, “connection bandwidth” and traffic. All of these are finite resources and cost money, especially high bandwidth handling solutions.
The problem with actual user connection speeds. Average user connections in US,Canada and UK are at around 2mbit. Business users usually have even slower connections and nearly all home users with “fast broadband” connections actually share the connection with other users. As a basic rule of the thumb if you have a network connection of 2mbit or more you should be able to watch non HD content pretty well. For HD content you do need a connection of 6-10mbps or higher.
Viewer’s computer performance. The majority of today’s laptops use integrated graphics. Most of business PC’s use integrated graphics too. The only IGM controllers that can play HD(540p or above) video smoothly are nvidia geforce 8 or newer and ati4000 series or newer, which constitute less then 10% of the market. In short most web users cannot handle anything above 405p(720 x 405) in resolution.

The above makes publishing HD video on a high demand website a big problem.

The “near HD” approach

Since all publishers generally want their content to look good and play smoothly there are hosting solutions that provide some of the benefit at reduced cost and risk.

Video Sharing services play a lot with the “HD video” buzzword for marketing purposes, but it is expensive to them to actually provide the service, so it gets placed as a feature that you need to explicitly enable or use under certain limiting conditions.

Near HD is a very loose term, depending on the source, but it is all about having better visual quality and still be able to do it with today’s technology. I consider “near HD” any video with resolution between 405p(720 x 405) and 576p(1024 x 576) with a bitrate between 800bkps and 2000kbps. These resolutions and bitrates are about the top of the line for today’s web.

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