Closed Captions. Questions. Jan Ozer #janozer 11/20/2014

Transcription

1 Closed Captions Jan Ozer #janozer Questions For more information, check out the book A beacon of light in a valley of half-knowledge Mustafa Isik, on Twitter 1

2 Agenda Introduction Definitions Creating captions Live VOD Choosing/using a caption format Introduction What are closed captions Who has to caption? Other reasons to caption? 2

3 What Are Closed Captions? Closed captions Designed for deaf or hard of hearing Incorporate all elements of audio experience: Background sounds Identify of speaker Closed can be disabled; open are burned in Subtitles Convert production to different language Translate from one language to another Speech Signs or other written documents Not background noises and sounds Who Has to Caption? Federal agencies (and those receiving federal funds) - Section 508 of the Rehabilitation Act "All training and informational video and multimedia productions which support the agency's mission, regardless of format, that contain speech or other audio information necessary for the comprehension of the content, shall be open or closed captioned." 3

4 Who Has to Caption? Broadcasters: Twenty First Century Communications and Video Accessibility Act of PlayMedia - Caption Requirements Caption Quality IP video captions must be at least the same quality as TV captions. Quality of captions will be assessed on completeness, placement, accuracy, and timing. Caption Style and End-User Control Following controls required - Font size, Font style, Character color, Opacity, Edge attributes, Caption background, Language selection, Preview/setting retention 4

5 Caption Requirements Caption Formats SMPTE-TT (Society of Motion Picture and Television Engineers Timed Text) caption format is a safe harbor interchange and delivery format. SMPTE-TT is not required, but recommended by the FCC. Devices that support SMPTE-TT are in compliance in regard to functionality. Other Potential Groups Schools, public universities, towns and municipalities (maybe) Title II of the Americans with Disabilities Act Section 504 of the Rehabilitation Act of

6 Other Reasons to Caption To expand viewers to hearing impaired To enable viewing in loud environments Improving video SEO RAMP is the most prominent supplier here Fox News, Golf Channel, Thomson Reuters Definitions Broadcast standards Digital formats Captioning techniques 6

7 Broadcast Formats CEA-608 captions analog broadcasts 60 characters a second Limited character set Embedded in line 21 of broadcast (called vertical blanking interval) CEA-708 captions for digital broadcasts Much more flexible character set and colors Generally embedded as text track into transport stream DCMP s Caption Key Guide is gold standard for best practices vs Streaming captioning is essentially CEA-608 7

8 608 vs. 708 (from CPC Web) Digital Caption Formats Too many to list. Prominent ones include SCC Scenarist Closed Caption good mezzanine SMPTE-TT (Timed Text) FCC safe harbor format TTML Timed Text Markup Language WebVTT the standard for HTML5, which also supports TV positioning and attributes DFXP WC3 TTML profile How do you choose? More later 8

9 Captioning Techniques Embedded captions Captions included in the compressed file Sidecar Captions included as separate file and linked programmatically by player Captioning Workflows Live Broadcast source with captions Create captions VOD Source with captions Other file 9

10 Live Source with Captions Most high end live encoders can pass through 608 or 708 source in necessary formats Caption I/O istreamplanet s Aventus platform. Live No Captions Need stenographer to create captions Find a service Uvault soup to nuts Other providers CaptionMax Caption Colorado 10

11 VOD with Digital Captions Most High end VOD encoders can input either 608 or 708 source and convert to necessary formats This is from encoding.com VOD With Embedded Captions Telestream MacCaption/CaptionMake r Full featured programs with: Extensive import/export format support Caption creation editing interface and workflows Integration with editors and DVD authoring program Embed captions into multiple file formats Automatic time stamping to convert transcription into captions Some single-function freeware tools CCExtractor SubRip 11

12 Captions in Other Sources Captions in optical discs MacCaption/CaptionMak er Captions in transcript Automatic time stamping to convert transcription into captions (Telestream) VOD Create Own Captions Third Party Services Upload video Download caption files in a range of formats Providers

13 Pricing from 3Play Cheaper Alternatives Upload video to YouTube YouTube does speech to text You cleanup Download as.vtt,.srt or.sbv files 13

14 Microsoft HTML Video Caption Maker Input URL Play file Type captions Export TTML or WebVTT Copy and paste HTML code (Dotsub has similar free tool) Captioning Rules (NCAM) 1. Captions should be a verbatim representation of what is being said, although you may edit out unnecessary speech (um..., ah..., er..., etc.). 2. Each caption should be composed of one or two rows and should be positioned in the bottom center of the caption region. Avoid using three-row captions except when using a speaker identification. 3. If you can fit a caption on a single row rather than two, do so. 4. Caption what is spoken: if the speaker says "string" when he meant to say "spring", for example, caption it as such. 5. Don't correct grammar-if you hear it, caption it. 6. End punctuation (period, exclamation point, question mark) indicates the end of a caption, and the next sentence starts with a new caption. 7. Points (...) may be used to indicate a pause, an interruption or a suspension within the caption, or as end punctuation. 8. When using two-row captions, avoid formatting them so that one line is substantially longer than the other. 14

15 Which Formats Third party service provider, product or plugin Online video platforms OTS Players (like JW Player) Cloud encoders Transcoders/media servers Other encoders Check which formats they require Online Video Platforms (OVP) Check their requirements 15

16 Off the Shelf Players Check their requirements Cloud Encoders We saw encoding.com Here s Zencoder 16

17 Transcoder/Media Server Wowza Media Server (more later) Other Encoders Telestream Vantage can add captions from.scc and other inputs to a variety of outputs Here s Sorenson Squeeze When working with an existing encoder, check the supported formats and be sure to supply 17

18 Caption Support by Distribution Format Flash ios Android HTML5 MSE/EME/DASH CE devices Flash Supports multiple formats, TTML is preferred (W3C Timed Text XML, formerly DFXP) y/products/flash/captions.html 18

19 Supporting Mobile Devices Two choices Support via apps you can use any caption format you want Support via native browser or player Must use specified format ios/http Live Streaming HTTP Live Streaming supports closed captions within streams When using stream segmenter, add CEA-608 closed captions to the MPEG-2 transport stream as specified in ATSC A/72. When using file segmenter, encapsulate your media in a QuickTime movie file and add a closed captions track ('clcp ) Live streaming also supports multiple subtitle and closed caption tracks in Web Video Text Tracks (WebVTT) format. 19

20 ios/http Live Streaming Android Android 4.1 was the first to support timed text tracks In band text track within MP4 or 3GPP source Out of band external text source WebVTT is preferred format 20

21 HTML5 Captions Can be embedded or sidecar Sidecar WebVTT format Real world HTML5 caption support next slide, courtesy of JW Player It s getting pretty good HTML5 21

22 Caption Support for Adaptive Formats HTTP Dynamic Streaming (HDS) Supports CEA-708 embedded in F4F fragments Embedded in data track as AMFO oncaptioninfo Embed in H.264 SEI NALU Uses TTML Format Smooth Streaming TTML DASH Two options; W3C TTML SMPTE TT 22

23 Distributing to Multiple Formats Two choices Prepare separate packages Transmux - Wowza Media Server (more later) Caption Automation For high volume use, consider tools with Batch operations via watch folder, GUI or command line interface Time tailor captions Adjusts captions when original materials are shortened or otherwise repurposed 23

24 Caption Automation Through acquisition of MacCaption/Caption Maker, Telestream is a leader in this market Offers a free trial for MacCaption and CaptionMaker at Or, to get a temp license to try out all the encoding decoding features, contact captioning team at [email protected], ph: I appreciate Telestream proofing this document (though all errors, omissions and misstatements are mine) Questions 24