Cross-platform Video Publishing

As part of our drive to get materials as platform independent as possible (including support for mobile devices) I’ve been having a good look into how we publish video such that it works over the Internet easily, AND can be downloaded for use on devices such as iPhones, iPads, and other smartphone platforms.

In general it would seem that most cross-platform video is moving towards the H264(AVC) video encoding standard – even Flash player now supports this alongside its proprietary FLV format. Many of the modern web browsers (such as Firefox and Google Chrome) now have native support for H264 videos as part of their support for HTML5, so this would seem to be the way to go.

So, the next thing is to see if we can get this working easily in Blackboard – I’ve recently started playing with an Open Source flash-based video player called FlowPlayer, which I’ve uploaded to the Blackboard Content Collection, and which is embedding and supporting H264 videos nicely – I’m going to try using this for the latest Clinical Skills videos, to see how usable this might be for students – the main concern here is that Flash support for H264 is available from Flash Player 9 and upwards, and I’m not sure what the uptake of this version is within the NHS – then there’s the issue of getting MP4 video files through Trust firewalls, but we’ll give it a go and see.

As for encoding videos to H264, first of all, when we’re considering cross-platform support it is worth bearing in mind that while the H264 encoding format is fairly open regarding video size, quality and frame-rate, many of today’s mobile devices have rather tighter limits, governed by their limited processing power. The Lifehacker website has an article that looks at the requirements for running video on most current mobile devices, which recommends the following limitations:

• Video encoding format: H264(AVC)
• Video size: 480 x 320
• Video quality (bit rate): 1500kbps or less
• Audio encoding format: AAC
• Audio bit rate: 128kbps or lower
• Audio sample rate: 44100 or less

I’ve actually found that a video bit rate of 384kbps is quite adequate at that size, and keeps the file size down too.

For getting videos into the required format I’ve found the free software Format Factory to be excellent, both for re-encoding existing video files, as well as for ripping video directly from DVD.

This, of course, needs testing. I’ve already tried this on my Android smartphone and it seems good. Next will be to try this on our iPad and and iPhone to check they’re OK. We also need to ensure the above concerns about web delivery are not going to cause a problem.