BBC Proms in Extra High Quality on the Internet: The Tech
This post explains the signal path used to deliver the 320Kb/s AAC internet stream of Radio 3 for the final week of the BBC Proms. For background information about the experimental extra high quality feed, you may wish to read the entry on the BBC Internet Blog and to listen to the audio, visit the web page hosting the experiment here.
The signal from the microphones at the Royal Albert Hall is converted on the stage to 48ks/s 24bit audio and sent to the outside broadcast vehicle over fibre. Each microphone has appropriate equalisation and time alignment applied and the sound is mixed down to stereo for broadcast on Radio 3.
Still at 24 bit 48ks/s the stereo audio is fed over an "E1" 2Mb/s circuit to London Broadcasting House and passes through the main audio router to the Radio 3 Continuity Studio. Here it is unfortunately necessary to sample rate convert the audio to 44.1ks/s. The reasons for this are largely historic...
Read more and comment at BBC Research & Development blog