Future Media Standards & Guidelines

Formatting Instructions for EBU-STL and Timed-Text Subtitles Files

1. Purpose

This document explains how to prepare and format subtitles files in the appropriate format so they can be used with online A/V content on BBC websites. The formats described are for timed-text and EBU-STL files.

As described in the Subtitling Guidelines, which sets out the BBC's requirement to deliver subtitles for online A/V content, subtitles must be provided in these formats so that they can be used reliably without user intervention and can be passed through the subtitling workflow without noticeable impairment to the viewers.

Refer to the BBC Subtitling Editorial Guidelines for advice on the best practice for creating subtitles files.

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2. In general

As a general rule, subtitles:

  • Must consist of no more than three lines;
  • Must contain no more than 32 characters in each line;
  • Must be centred at the bottom of the video clip; and
  • Should include colours to distinguish speakers from each other – namely, white, yellow, cyan and green.

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3. Preparing your subtitles

Subtitle preparation is a time consuming activity. To aid this process, you should deliver an electronic copy of the script for the A/V content to the subtitling provider commissioned to produce subtitles. This script should be provided in either .doc (Microsoft Word), .txt or .rtf file formats.

If you deliver the script as a .txt file choose Unicode UTF-8 or UTF-16 encoding when you save to ensure that all the characters are correctly interpreted. This encoding option is available for text files in most editors, such as Microsoft Notepad or TextEdit for Mac OS.

The script should accompany the VHS copies of the programme (with VITC and burnt-in time code to match the programme) or digital media format that is to be subtitled.

A script can also be used as a text alternative to a video clip.

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4. Formatting instructions for EBU-STL subtitles files

If you are providing EBU-STL subtitles files, they must comply with the EBU-N19 standard Subtitling Data Exchange Format (EBU Document Tech. 3264 E) at level 1. Refer to this document for full instructions on creating EBU-STL subtitles files.

EBU-STL subtitles files need to be converted to timed-text format for inclusion with online A/V content.

In general:

  • The file extension for the EBU-STL format is .stl.
  • Only characters authorised by the EBU standard can be used for each subtitling language. The use of any unauthorised characters causes subtitling errors during broadcasting, and subsequently in the EMP, which is used to display to A/V content and its subtitles online.
  • Subtitles for each EBU-STL file for A/V content must start from 10:00:00:00.
  • Subtitles for each EBU-STL file for marketing trails must start from 15:00:00:00.

The UX&D subtitle conversion facility (SCF) can detect colour information within EBU-STL and make sure that this information is included within timed-text subtitles file during the conversion process.

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5. Formatting instructions for timed-text subtitles files

The file extension for the timed-text format is .xml. You need to structure the file for each video clip as shown in the example below:

			
<?xml version="1.0" encoding="UTF-8"?>
<tt xmlns="http://www.w3.org/2006/10/ttaf1" xmlns:ttp="http://www.w3.org/2006/10/ttaf1#parameter" ttp:timeBase="media" xmlns:tts="http://www.w3.org/2006/10/ttaf1#style" xml:lang="en" xmlns:ttm="http://www.w3.org/2006/10/ttaf1#metadata">

<head>
<metadata/>

<styling>
<style id="s0" tts:backgroundColor="black" tts:fontStyle="normal" tts:fontSize="16" tts:fontFamily="arial" tts:color="white" />
</styling>
<layout/>
</head>
 
<body tts:textAlign="center" style="s0">

<div>

<p begin="00:00:00.100" end="00:00:01.800">Accessing latest information.</p>
<p begin="00:00:02.300" end="00:00:05.000">Data files relating to<br/>Martin Truman and his ability</p>
<p begin="00:00:05.100" end="00:00:06.600">to predict the future<br/>through the use</p>
<p begin="00:00:06.700" end="00:00:09.800">of astrology shows evidence<br/>of unusually high accuracy.</p>
<p begin="00:00:10.100" end="00:00:13.100">Although initial scans reveal<br/>that self declared Messiah</p>
<p begin="00:00:13.200" end="00:00:16.300">of the Zodiac Martin Truman<br/>is, in fact, completely human,</p>
<p begin="00:00:16.600" end="00:00:18.200">it would seem that<br/>he has the ability</p>
<p begin="00:00:18.300" end="00:00:21.500">to demonstrate some unusual<br/>powers, including firing bursts</p>
<p begin="00:00:21.600" end="00:00:23.300">of unknown energy<br/>from his hands.</p>
<p begin="00:00:23.500" end="00:00:25.600">Described as "The<br/>Ancient Lights,"</p>
<p begin="00:00:25.700" end="00:00:27.700">the energy Truman<br/>harnesses seems to burn</p>
<p begin="00:00:27.800" end="00:00:29.200">with no detectable evidence.</p>
<p begin="00:00:29.500" end="00:00:31.100">Additionally, Truman seems</p>
<p begin="00:00:31.200" end="00:00:34.000">to have hijacked the television<br/>show "Paranormal Planet"</p>
<p begin="00:00:34.300" end="00:00:36.800">and is broadcasting it<br/>worldwide on all channels</p>
<p begin="00:00:36.900" end="00:00:39.600">with no detectable interference<br/>to the television signal.</p>
<p begin="00:00:40.200" end="00:00:43.000">A video fact file relating<br/>to this activity is stored</p>
<p begin="00:00:43.100" end="00:00:44.400">in the Video Updates module.</p>
<p begin="00:00:44.600" end="00:00:47.000">Other than the unusual<br/>activities already observed,</p>
<p begin="00:00:47.400" end="00:00:48.300">nothing is happening.</p>
<p begin="00:00:48.700" end="00:00:49.600">Nothing is happening.</p>
<p begin="00:00:50.200" end="00:00:51.100">Nothing is happening.</p>
<p begin="00:00:51.500" end="00:00:53.800">Nothing is happening.</p>
<p begin="00:00:54.800" end="00:00:57.900">Soon, all the signs will<br/>come under my power.</p>
<p begin="00:00:58.200" end="00:01:00.200">At the becoming of<br/>The Ancient Lights,</p>
<p begin="00:01:00.400" end="00:01:02.600">I will be King of the World!</p>
<p begin="00:01:02.900" end="00:01:04.400">Stand ready.</p>
</div>
</body>
</tt>

When creating timed-text subtitles files, ensure you include:

  • begin="" and end="" attributes
  • line breaks (<br/>)
  • Time codes of the format hh:mm:ss,zzz (hours: minutes: seconds, milliseconds)

You can include colour information within XML subtitles files to represent different speakers if you wish. If you do then the file should follow the structure in the example below:

<?xml version="1.0" encoding="UTF-8"?>
<tt xmlns="http://www.w3.org/2006/10/ttaf1" xmlns:ttp="http://www.w3.org/2006/10/ttaf1#parameter" ttp:timeBase="media" xmlns:tts="http://www.w3.org/2006/10/ttaf1#style" xml:lang="en" xmlns:ttm="http://www.w3.org/2006/10/ttaf1#metadata">

<head>
<metadata/>

<styling>
<style id="s0" tts:backgroundColor="black" tts:fontStyle="normal" tts:fontSize="16" tts:fontFamily="arial" tts:color="white" />
</styling>
<layout/>
</head>
 
<body tts:textAlign="center" style="s0">
<div>

<p begin="00:00:00.100" end="00:00:01.800"><span tts:color="red">Accessing latest information.</span></p>
<p begin="00:00:02.300" end="00:00:05.000"><span tts:color="red">Data files relating to<br/>Martin Truman </span>and his ability</p>
<p begin="00:00:05.100" end="00:00:06.600"><span tts:color="yellow">to predict the future<br/>through the use</span></p>
<p begin="00:00:06.700" end="00:00:09.800"><span tts:color="yellow">of astrology shows evidence<br/>of unusually high accuracy.</span></p>
<p begin="00:00:10.100" end="00:00:13.100"><span tts:color="cyan">Although initial scans reveal<br/>that self declared Messiah</span></p>
<p begin="00:00:13.200" end="00:00:16.300"><span tts:color="cyan">of the Zodiac Martin Truman<br/>is, in fact, completely human,</span></p>
<p begin="00:00:16.600" end="00:00:18.200"><span tts:color="green">it would seem that<br/>he has the ability</span></p>
<p begin="00:00:18.300" end="00:00:21.500"><span tts:color="green">to demonstrate some unusual<br/>powers, including firing bursts</span></p>
<p begin="00:00:21.600" end="00:00:23.300"><span tts:color="yellow">of unknown energy</span><br/><span tts:color="cyan">from his hands.</span></p>
<p begin="00:00:23.500" end="00:00:25.600">Described as "The<br/>Ancient Lights,"</p>
<p begin="00:00:25.700" end="00:00:27.700">the energy Truman<br/>harnesses seems to burn</p>
<p begin="00:00:27.800" end="00:00:29.200">with no detectable evidence.</p>
<p begin="00:00:29.500" end="00:00:31.100">Additionally, Truman seems</p>
<p begin="00:00:31.200" end="00:00:34.000">to have hijacked the television<br/>show "Paranormal Planet"</p>
<p begin="00:00:34.300" end="00:00:36.800">and is broadcasting it<br/>worldwide on all channels</p>
<p begin="00:00:36.900" end="00:00:39.600">with no detectable interference<br/>to the television signal.</p>
<p begin="00:00:40.200" end="00:00:43.000">A video fact file relating<br/>to this activity is stored</p>
<p begin="00:00:43.100" end="00:00:44.400">in the Video Updates module.</p>
<p begin="00:00:44.600" end="00:00:47.000">Other than the unusual<br/>activities already observed,</p>
<p begin="00:00:47.400" end="00:00:48.300">nothing is happening.</p>
<p begin="00:00:48.700" end="00:00:49.600">Nothing is happening.</p>
<p begin="00:00:50.200" end="00:00:51.100">Nothing is happening.</p>
<p begin="00:00:51.500" end="00:00:53.800">Nothing is happening.</p>
<p begin="00:00:54.800" end="00:00:57.900">Soon, all the signs will<br/>come under my power.</p>
<p begin="00:00:58.200" end="00:01:00.200">At the becoming of<br/>The Ancient Lights,</p>
<p begin="00:01:00.400" end="00:01:02.600">I will be King of the World!</p>
<p begin="00:01:02.900" end="00:01:04.400">Stand ready.</p>
</div>
</body>
</tt>

If using colours, the timed-text file should include the following attributes to display colours for different speakers:

<span tts:color="red"></span>
<span tts:color="yellow"></span>
<span tts:color="cyan"></span>
<span tts:color="green"></span>
		

The current version of the EMP does not support colour information within timed-text format; however, this feature will be available in future releases.

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