Test for WCAG failure F8: captions omitting some dialogue or important sound effects

[hannolans]

http://www.w3.org/TR/2013/NOTE-WCAG20-TECHS-20130905/F8

This describes a failure condition for all techniques involving captions. If the "caption" does not include all of the dialogue (either verbatim or in essence) as well as all important sounds then the 'Captions' are not real captions.

Examples of text streams that are not captions include:

• text that contains the dialogue (possibly simplified dialogue) but that does not describe important sounds
• text that omits dialogue during portions of the material

Procedure

1. View the material with captioning turned on.
2. Check that all dialogue is accompanied by a caption.
3. Check that all important sounds are captioned.

[hannolans]

Ad 2: We could set up a test has as input the caption text and the video file. If the browser QUAIL is running on is webkit, we can use the realtime speech to text function Web Speech API. The speech will get analysed (by a Google service) and you'll get the transcription back. Google has a session limit of 60 seconds, but that should be enough for us to detect if there are valid captions provided.
http://stiltsoft.com/blog/2013/05/google-chrome-how-to-use-the-web-speech-api/

So test would be:

1. play 30 seconds of video and send the audio via de streaming API to the web speech API.
2. check if there are captions for that given time span
3. check the words that the web speech API returns and the captions match (to a certain degree)
   Tests 3 and 4 should be true.