Ofcom commenced its caption quality measurement project in in 2013. The latest report, Measuring live subtitling quality (note, captions are called subtitles in the UK) is based on samples of live captioning broadcast by the BBC, ITV, Channel 4, Channel 5 and Sky. Its key findings are:
- The average accuracy rate of captions in the samples was 98.55%, which is the highest recorded during the four rounds of sampling. Ofcom attributes this to an increase in the use of pre-prepared captions and a decrease in technical faults.
- The average latency (the timelag between the audio and corresponding captions appearing on screen) was 5.6 seconds, which is in line with the three previous reports. This is higher than Ofcom’s recommended maximum of 3 seconds.
- On average, caption speeds were lower than the recommended 160-180 words per minute, but 92% of samples had short bursts of very fast captions (exceeding 200 words per minute).
The report notes that the BBC and Channel 4 have been working with their access supplier Ericsson on a method of reducing latency by inserting short delays in live programs.
Ofcom will now consult with caption users, broadcasters and access suppliers to decide whether there should be any changes to its captioning guidelines.
On 19 November, the Australian Communications and Media Authority (ACMA) released a discussion paper entitled ‘Review of the Television Captioning Standard’.
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