Friday 14 March 2014, 11:21
Radio 3 Audio Innovation
Radio 3 has a long history of pushing the boundaries with new technology, from early stereo broadcasts in 1958 through wide dynamic range high bit rate audio (HD Sound) to binaural presentation (surround sound in headphones). In collaboration with BBC R&D, we have a new experiment for you to try. For two weeks from 15th to 31st March some of our evening concerts from London’s Southbank Centre will be available in surround sound. This is an experiment so it may not work for you, if you just want to listen to the concerts in the normal way, you can enjoy them here.
You can read more about the experiment and find links to the R&D Blog and FAQ further down the page, but if you just want to try the experiment you will find the player here but please remember the experiment is only running during our evening concerts, details can be found here.
There is a new standard for HTML, the language that operates the World Wide Web, called HTML5. It includes an Audio API (application programming interface) which for the first time allows a web browser to play surround sound without the need to download and install additional software. It also includes the Mediasource API, which enables us to use MPEG-DASH, a new standard for media delivery, to get the data to you. Not all web browsers fully support HTML5 (particularly the Mediasource API) yet; we have tested the experiment using Chrome under Windows 7 and Mac OSX, but it might work with other combinations of computer and browser. Although an HTML5 browser can easily play a surround sound file encoded with AAC, we think we are first to get a browser to play a live audio stream without plug-ins but would love to hear from anyone else who has done it.
You can read more about the technical aspects of this experiment on the R&D blog.
What do you need?
You will need a computer with an HTML5 compatible browser (such as the latest version of Chrome on Windows or Mac, or IE11 under Windows 8.1) and a means to replay surround sound. You could use a multi-channel sound card connected to the computer by USB or you may have luck with an HDMI connection from your computer to a home cinema setup. If you set up something specially to enjoy the experiment you don’t need to worry about the centre or subwoofer channels as we won’t send any audio to them, but some systems with small speakers put all the bass through the subwoofer in which case you will still need it connected.
What will you hear?
You will hear the concerts in 4.0 rather than the 5.1 presentation usually used for feature films. There won’t be any helicopters or explosions so we don’t need the '0.1' LFE channel. We won’t be using the centre channel because it's easier for us to create a surround sound balance without compromising the main stereo programme if we only use two speakers at the front. Not all concerts will be available in surround sound, when the experiment isn’t running you will hear a test announcement. If you are listening on a computer surround sound system you are probably nearer the front speakers than the rear ones; in a home cinema you are probably nearer the rear speakers than the front ones, so you may need to adjust the front to back balance to get a good sound. The rear speakers will carry reverberation during the performance, which should give you a more realistic sense of location within the venue than you get with stereo. You should find applause comes from all around you, helping you feel part of the audience.
During the interval, you will only hear normal stereo.
Philip Burwell describes the experiment from the sound balancer’s perspective
There have been many experiments in mixing surround sound over the past 40 years or so. Generally, they involve either rigging special microphone arrays, or processing the sound electronically to mimic the effect of surround. On a Super Audio CD, there will often be two separate mixes embedded into the disc, one stereo and one surround. Many TV broadcasters have to broadcast live on several platforms at the same time, so down-mixers, or ‘black boxes’ may be used to convert surround to stereo without the intervention of the sound balancer. In our experiment we are using neither of these approaches. For reasons of efficiency, we are using just one mixing desk to provide both the stereo and 4.0 mixes, with some extra microphones rigged in the hall. Our approach, to put it very simply, is to enhance the live stereo mix with some hall ambience in the rear loudspeakers. We hope you enjoy the experience.
How can we give feedback?
You can give feedback by commenting to this blog, or on Twitter using hashtag #BBCR3surround.
What if it doesn’t work?
As this is very experimental I’m afraid we can’t give you individual help getting it working; if you can’t make it work or just don’t like it, please let us know, and you can always listen using our high quality HD Sound internet stream from the Radio 3 homepage.
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