MPEG4 on dShed
For the last eight years Watershed has always distributed video over the Web using QuickTime .mov files. The last time we explored encoding and distribution standards was during the research stage of the Digitised project in 2001. As we start to think about dShed and the implications of a digital archive it's time to look at how we produce, and our users consume, video.
As all of the video content becomes part of the dShed archive we need to think about what is best for the future users of the archive not just the users of dShed this week.
The move away from Sorenson Video codec in QuickTime could be a painful process. Using MPEG4 pt10 files in Electric December 2005 meant that almost all of Watershed's staff were unable to view the video content. The public viewing computers around the building all required upgrades.
Apple have set the hardware and OS bar quite high for QuickTime 7, especially (and ironically) for Macintosh users. Many Windows users are reticent about upgrading to QuickTime 7 because the most prominently displayed installer installs iTunes as an 'added extra'. iTunes will probably become Apple's default media player in the future replicating the UI mistakes Real made almost 10 years ago.
The transition to MPEG4 will be a gradual process. Currently some QuickTime files use h264 and AAC encoding. Even when the files become fully compliant we will still push the files through the QuickTime plug-in to maintain a consistently good user experience (unless they don't have QuickTime installed).
Using h264 and AAC gives much smaller file sizes for the equivalent quality. This saving can be substantial with thousands of visitors viewing large video files. We get reduced bandwidth costs and the users spend less time downloading and more time viewing. Other advantages include local colour and gamma correction. Some people compress a different version with colour and gamma settings for each platform; we didn't. Previously, the gamma was set somewhere between that of a Macintosh and a Windows PC, with no user getting the best experience.
We may lose some content viewers by requiring QuickTime 7 to view the video in the browser but we will gain many more users by leveraging a common, standard media format that is supported by low power consumption, hardware decoders in a variety of portable devices. The iPod and PSP currently account for most of these, but their share will diminish as more and more mobile phones get the decoders.
New distribution methods, such as video podcasts, allow us to broadcast further to an audience that has 'opted in' to view specific content. After we added a 90 Second Challenge video podcast to the iTunes Music Store, even before video iPods were released, the feed accounted for 62% of all traffic to dShed.
In the short-term we may loose up to 30% of current potential viewers but will gain more than a 300% increase through new deployment opportunities.
The podcast distribution format appears almost too good to be true. It took half a day to add the podcast to the web application. The podcast is marketed by Apple (using iTMS) and other directory sites to a very large number of users at no cost or effort on our part. It is quite wondrous when comparing the time and money spent developing large content umbrella and directory sites. There may even be a situation where we don't need a web-site - just a podcast.