In order to prepare Measuring live subtitling quality: Results from the second sampling exercise (note, captioning is called subtitling in the UK), Ofcom required the BBC, ITV, Channel 4, Channel 5 and Sky to measure the quality of a sample of live captioning broadcast between April and May 2014.
The report’s key findings are as follows:
- A significantly higher proportion of live programs had pre-prepared block captions (i.e. captions which appear as blocks of text rather than one word at a time).
- Samples of news and entertainments programs had median accuracy rates of 98.8% and 98.9% respectively.
- Over half the samples of chat shows failed to reach the accuracy target of 98%.
- In some cases, pre-prepared captions were cued out by the captioner too quickly, making them difficult or impossible to read.
- Latency, or the delay between the audio and the captions appearing, was still problematic. The median latency was 5.8 seconds, while Ofcom’s recommended maximum is 3 seconds.
The increase in the use of pre-prepared block captions in news programs is particularly encouraging. The BBC and ITV both told Ofcom that they had been working with their caption suppliers more closely, providing them with scripts and other materials which allow them to prepare caption files in advance.
In Australia, the Seven Network has always used this model of switching between live and pre-prepared captions, sometimes called the ‘hybrid’ method, for its news programs. At the Deafness Forum Captioning Awards on 31 October, the Nine Network won the Organisational Commitment award, in part because it has also moved to this model.
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