Subtitling Services in London and the UK

Subtitling services are professional audiovisual translation services that transcribe spoken dialogue, time-code each line, translate it into one or more target languages, and deliver synchronised text overlays in subtitle file formats such as SRT, WebVTT, EBU-STL, TTML, SCC, SBV, and DFXP for video. The discipline combines linguistic translation, technical spotting, and broadcast-grade file engineering, executed by trained subtitlers rather than generalist translators. Unlike a straight document translation, every subtitle line must fit a strict reading-speed limit and a maximum line width, so the subtitler is simultaneously a linguist, an editor, and a timing engineer.

Our subtitling output covers five service categories:

• Monolingual captions for social-media silent autoplay.
• Translated subtitles for international distribution across 80+ languages.
• SDH for Deaf and hard-of-hearing accessibility.
• Burnt-in subtitles rendered permanently into MP4 for LinkedIn, Instagram, and Facebook.
• Live subtitling for conferences and webinars.

Every project we deliver is underpinned by ISO 17100 quality standards, meaning a bilingual revision stage is built into every workflow as standard — not offered as an optional upgrade. That commitment to quality means clients across corporate, film and TV, e-learning, legal, and medical sectors trust us to represent their content accurately in any language.

How do subtitles differ from closed captions and SDH?

Subtitles translate dialogue for viewers who can hear the audio but do not speak the source language, whereas closed captions transcribe dialogue and add sound cues and speaker identifications in the same language for accessibility. SDH — Subtitles for the Deaf and Hard of Hearing — combine translated dialogue with those same sound-effect descriptions and speaker labels, making them suitable for Deaf audiences watching foreign-language content. The three formats serve different audiences, trigger different file conventions, and carry different legal weight under UK accessibility law.

What is audiovisual translation?

Audiovisual translation is the professional discipline covering subtitling, dubbing, voice-over, and closed captioning, applied to films, corporate video, e-learning, and broadcast content. The field also overlaps with our Audio Translation Services for podcast and conference audio, and with our Voice-Over Services when clients prefer dubbed dialogue over on-screen text. Whichever format a project requires, the foundation is always the same: accurate linguistic transfer, precise timing, and a deliverable that performs flawlessly on every platform where it is published.

What types of subtitling services are available?

We provide six types of subtitling services: monolingual captions, translated subtitles, SDH for accessibility, burnt-in (open) subtitles, closed-caption sidecar files, and live subtitling for events and webinars. Each type matches a specific distribution channel, compliance regime, and file deliverable, so the first step in any brief is matching the correct service type to the client’s platform and audience requirements.

What is monolingual captioning?

Monolingual captioning transcribes spoken dialogue into on-screen text in the same language as the audio, typically for social-media silent autoplay and same-language accessibility. The output is a WebVTT or SRT sidecar file timed at no more than 17 characters per second, with optional speaker labels when more than one voice appears in the programme. Monolingual captions are the fastest and most cost-effective subtitling service we offer and serve as the foundation for every subsequent translation.

What are translated subtitles?

Translated subtitles convert source dialogue into a target language with precise time-coded synchronisation, used for international distribution of corporate, training, and broadcast video. The translation step compresses each line to fit a 42-character maximum width while preserving meaning, register, and cultural references — a task that demands both linguistic skill and editorial judgement. We deliver translated subtitles across more than 80 languages, with each project handled by a native-speaking linguist who is matched to the subject matter of the video.

What are SDH subtitles?

SDH subtitles combine translated or same-language dialogue with sound-effect descriptions and speaker labels for Deaf and hard-of-hearing viewers, as required under the UK Equality Act 2010 for many public-facing videos. SDH carries the accessibility content of closed captions inside subtitle-style formatting and positioning, making it the dominant format on major streaming platforms and a standard deliverable for UK broadcast clients. We produce SDH as a standalone service and as part of broader multilingual packages for film, TV, and corporate video.

What are burnt-in (open) subtitles?

Burnt-in subtitles are rendered permanently into the video frame and cannot be switched off by the viewer, used for LinkedIn, Instagram, and Facebook video where audiences watch without sound. Open captions remove the need for a sidecar file, guarantee identical appearance across every device and platform, and survive re-uploads and third-party compression. We deliver burnt-in subtitles as a finalised MP4 alongside the optional sidecar file so clients retain a switchable version for platforms that support it.

What is live subtitling?

Live subtitling produces real-time captions for webinars, conferences, and broadcast streams using trained respeakers or stenocaptioners, with latency typically under five seconds. Live workflows use ASR-assisted respeaking combined with a human corrector, delivering accuracy above 98% for scripted or prepared content and 94–96% for spontaneous dialogue. We support both on-site events in London and remote live-caption integration for virtual and hybrid broadcast productions.

Which subtitle file formats are available?

We deliver subtitles in eight industry file formats: SRT, WebVTT, EBU-STL, TTML, SCC, SBV, DFXP, and burnt-in MP4, matched to the destination platform such as YouTube, Netflix, BBC iPlayer, or corporate LMS.

When should you use SRT or WebVTT?

SRT and WebVTT are lightweight sidecar formats used for YouTube, Vimeo, LinkedIn, and HTML5 web players, supporting basic timing and limited styling. SRT carries no styling beyond italics; WebVTT adds positioning, colour, and CSS class hooks for richer accessibility on modern web players.

When is EBU-STL or TTML required?

EBU-STL is the broadcast standard required by UK and European broadcasters including the BBC and Channel 4, while TTML (and its Netflix-DFXP variant) is required by streaming platforms such as Netflix and Amazon Prime. The EBU specification (EBU Tech 3264) defines the binary STL container used in linear TV pipelines.

What turnaround times are available for subtitling in London?

Standard turnaround for subtitling in London is 24 hours for video up to 10 minutes, making it practical to commission subtitles on a Monday morning and receive broadcast-ready files by Tuesday morning. Multilingual projects covering three to five languages and up to 30 minutes of runtime are delivered within 72 hours as standard, because a shared spotting base lets language teams work in parallel rather than sequentially. Rush options reduce English caption delivery to as little as four hours, and same-day delivery is available for legal-evidence and breaking-news footage of up to 15 minutes.

Confidential footage moves via SFTP with AES-256 encryption as standard, or by bonded London courier when client policy prohibits cloud transit entirely. Project managers in our London office coordinate every brief during UK business hours, and after-hours rush work is routed to a duty linguist for a sub-four-hour response. Turnaround commitments are confirmed in writing at the point of instruction, so clients have a contractual delivery time rather than an estimate.

For longer content — feature-length films, full e-learning courses, or corporate series exceeding 60 minutes — we produce a detailed production schedule at brief stage, breaking the project into batches so clients can review and approve early segments while later ones are still in production. This staged delivery model reduces the total elapsed time for large projects without adding risk to quality or consistency.

How does UK accessibility law affect subtitling requirements?

UK accessibility law creates subtitling obligations under three distinct frameworks, each targeting a different class of video content. The Equality Act 2010 requires service providers to make reasonable adjustments for Deaf and hard-of-hearing audiences, which in practice means adding SDH or closed captions to public-facing video wherever it is a proportionate step. Failing to subtitle a public-facing training or information video can constitute a failure of the reasonable-adjustment duty, exposing organisations to tribunal claims.

• Equality Act 2010 — service providers are required to make reasonable adjustments, including SDH on public-facing video, for Deaf and hard-of-hearing viewers.
• Ofcom Code on Television Access Services — licensed UK broadcasters must meet subtitling, signing, and audio-description quotas, rising to 80–100% subtitling coverage for qualifying channels.
• European Accessibility Act 2025 — streaming services and corporate video products sold into EU markets carry new accessibility obligations that extend beyond broadcast into on-demand and enterprise video.
• WCAG 2.1 Level A (SC 1.2.2) — captions are required for all prerecorded synchronised media published on public-sector websites in the UK.

SDH is the default deliverable whenever a video appears on a public-facing channel, a regulated broadcast slot, or an EU-distributed streaming catalogue, because it satisfies the accessibility requirements of all three frameworks simultaneously. Producing SDH alongside translated subtitles from a shared spotted transcript adds minimal cost to a multilingual project and eliminates the need to return for a separate accessibility pass later. We advise clients on which framework applies to their specific use case and build the appropriate deliverable into every project brief from the outset.

How do you request a subtitling quote?

Request a subtitling quote by sending the video file or a private streaming link, specifying source and target languages, deliverable file formats, and required turnaround, and receive a fixed GBP quote within one business hour.

1. Upload the source video via SFTP or share a private Vimeo/YouTube link.
2. Confirm source language and target languages (e.g., English → Spanish, French, German).
3. Specify deliverable formats (SRT, WebVTT, EBU-STL, TTML, burnt-in MP4).
4. State turnaround: standard 24 hours, rush 4 hours, or scheduled batch.
5. Receive a fixed GBP quote with no per-word variance within 60 minutes during UK business hours.

Start by submitting your brief via the Request a Subtitling Quote page.