Accessible progress: Subtitles are coming to live iPlayer streams

Available on desktop iPlayer now

In a move that is a world first, the BBC is to trial the use of subtitles for live channels on its video-on-demand service iPlayer.

The move should improve accessibility of the service for users who are hearing impaired, who already benefit from the use of subtitles on iPlayer's on-demand programming.

Currently the live-subtitling functionality is only available on desktop versions of iPlayer on PC and Mac, but it should be coming soon to mobile, tablet, and eventually television apps.

All the major BBC channels, from BBC One to CBBC and BBC News, are supported.

An accessible history

Subtitling on live broadcast TV has been provided as standard for some time. Pre-recorded shows will be transcribed ahead of time, but subtitles for live TV are created in an entirely different way.

For live TV an individual will sit and listen to a TV feed live and say out loud every word that is said by an individual on TV. This second-hand voice is then automatically transcribed by transcription software.

Transcription software is not used on the live feed itself, because of the difficulties of understanding multiple different voices alongside background noise from a television program.

However, the system is not without its faults. A report by television regulator Ofcom in 2015 labelled certain subtitles "unwatchable".

Meanwhile, online services such as YouTube automatically transcribe dialogue from the video feed itself, without it being re-spoken to clean the feed that the software has to process.

YouTube's transcription, however, has its own set of problems.

We have asked the BBC for details on which method of transcription it will be using and will update this piece when it responds.