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Visualising Radio - delivering video and audio

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Alan Ogilvie Alan Ogilvie | 16:02 UK time, Thursday, 22 January 2009

So, I just wanted to answer some of the queries we've been having about the audio and video that was used for the Visualising Radio trial.

My team - Terry O'Leary and Toby Bradley - organised the streaming elements, as we do for much of the music events we cover on a regular basis, as well as things like 'ScottCam' which you will remember from last year.

The first thing is a discussion about the audio, and a quick explanation (I've tried to write this in simpler terms, so audiophiles please suppress your urge to correct my terminology).

Heavily compressed audio tends to have a very 'flat' or 'upfront' dynamic range - which means that it doesn't 'sit' with a video track. There is no perspective with the audio. Visualising Radio was about taking the Radio 1 output and putting a video track together with an audio track - this proved an interesting challenge, one that isn't initially obvious.

The Radio 1 broadcast to FM, DAB, Freeview,... has significant audio compression applied at the studio - this is the 'sound' of Radio 1. If you were to use this against a piece of video there would be a feeling of 'dislocation' between the audio you here and the video you see.

So, as part of the trial, we decided to use a different audio feed from the studio - that had some audio compression but not nearly as much as the traditional broadcast feed. This would allow us to see how it 'felt'. Though if vis-radio is 'glanceable' then perhaps we need to review this, plenty of feedback from running this test though.

In terms of the video stream - we used Flash Media Encoder, running on a Windows XP based laptop connected to the BBC's Live Flash delivery network via a standard SDSL. (Tristan mentioned this previously) The video is encoded with On2 VP6 codec, and the audio input (above) is encoded to MP3 - all wrapped neatly and delivered via RTMP streaming from Flash Media Server.

Terry was our streaming engineer for the week, sitting with the vision mixer on site (Will Kinder), in with Moyles in the mornings and Switch on Sunday evening.

Here is a clip of the Visualising Radio console in action, this is from archive so the quality is a bit poor. (Thanks to Toby for editing this)

Visualising Radio Console from Alan Ogilvie on Vimeo.


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