This article explains what closed captions are, and how to use them on Twitch.
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Twitch users are now able to follow the conversation on stream thanks to a Live Closed Captions service on Twitch-produced content. Whether you have a hearing impairment or just want to squeeze a little Twitch into your library study session, you will not miss out on Twitch-produced content when listening to the audio is not an option.
Live Closed Captions on Twitch are typed live (very quickly!) by a professional stenographer hired to cover Twitch events such as Twitch Weekly and some stage events at TwitchCon. Captions are written as they are said so that nothing is missed. You can also adjust caption size, color, placement, and other settings to improve visibility for each user and each stream. Your settings will be saved and used to display captions any time they are available on a stream or if you re-watch a Past Broadcast from a stream that was captioned.
Captions elsewhere on Twitch can be provided by broadcasters who are able to transmit caption files embedded in their streams or via their broadcast encoders.
As a broadcaster, if you want to offer captions to your audience, you will need to transmit caption files in an accepted format embedded in your stream, or alongside your stream, through your broadcast encoder.
The Live Closed Captions system on Twitch accepts captions in line 21 CEA-708/EIA-608 format and in CC1 NTSC field 1.
Keep in mind: you are responsible for all content that appears on your broadcast, including captioned content. Using the Closed Captions system in a manner that violates Twitch’s Community Guidelines or Terms of Service may result in a suspension of your Twitch account.
Captions may be transmitted using one of the following methods:
CEA-708/EIA-608 embedded in the video elementary stream as described in ATSC A/72 (SEI user_data). This format is common among television broadcast encoders.
CEA-708/EIA-608 transmitted via RTMP onCaptionInfo script/AMF0 tag. This format is common among Internet broadcast encoders and media servers such as Elemental Technologies and Wowza.
When transmitting via RTMP, the payload must contain an ECMA Array with two element pairs:
A string named "type" containing the characters "708"
A string named "data" that contains a base64 encoded CEA-708/EIA-608 payload
Q: How do I know if a stream or video has captions?
A: When captions are available on a live stream or video, you will see a “CC” button that lets you turn captions on or off.
Q: What channels will be sure to have Closed Captioning?
A: As of September 9, 2016, ‘Twitch Weekly’, a show about all things Twitch, will air with live captions every Friday at 1 PM PT / 4PM ET on an ongoing basis. As well, the live stream from the Kappa Theater at TwitchCon 2016, September 30 - October 2, will also air with live captions.
Q: Do I have to update my settings every time a stream has captions?
A: No. Once you turn captions on or off or adjust the display settings, your preference will be saved for the next time you watch content that supports captions.
Q: Why do you call them “Closed Captions” are there “Open Captions”?
A: Yes! In short, Open Captions are always visible to viewers, but Closed Captions can be turned on or off. We want to give viewers the choice to use captions or turn them off whenever they are available.