How to Scale Subtitling: The Journey to Full Automation

Subtitling is no longer a ‘nice to have’. Since June 28th, the European Accessibility Act has made subtitles mandatory for broadcasters and streaming services operating in the European market. With the surge in content production and the exponential growth of short-form and on-demand video, broadcasters and content producers are faced with a crucial challenge: how to meet accessibility standards while maintaining efficiency and quality?

At Limecraft, we’ve been at the forefront of this evolution, enabling media professionals to streamline subtitling workflows – whether you need high-quality human-crafted subtitles or efficient, automated processes for large volumes of content. This article unpacks the different levels of automation available, helping you understand how to choose the right approach for your organisation.

Limecraft – A Track Record of Innovation

Limecraft’s leadership in automated subtitling is built on more than a decade of innovation. After pioneering with embedding Automatic Speech Recognition (ASR) at the core of the workspace back in 2013, Limecraft partnered with Belgian broadcaster VRT in the STON project (Spraak Technologie voor ONdertiteling), delivering the first AI-assisted subtitling system in 2016. By 2017, we were supporting the BBC, and in 2018 ITV Access Services joined our customer base to overhaul their internal subtitling operation.

In 2019, Limecraft received the NAB Product of the Year Award, recognising the impact of our end-to-end media subtitling and localisation solution. Fast forward to today, Limecraft consistently benchmarks as the number one choice for professional, broadcast-grade subtitling workflows, combining speed, accuracy, and configurability.

Why Media Companies and Language Service Providers choose Limecraft: Integration and Efficiency

At the heart of our customer’s success is Limecraft’s obsession with usability. Every feature is designed to minimise the number of clicks, and to integrate seamlessly into existing workflows.

Limecraft connects effortlessly with popular editing platforms like Avid Media Composer and Adobe Premiere Pro through custom panels. We offer direct integrations with Ooona for linguistic services and subtitle file management, and we support a wide range of subtitle file formats for maximum compatibility.

Our approach to subtitling is not just about AI; it’s about workflow optimisation, giving customers the flexibility to choose between fully automated and semi-automated processes depending on their operational needs.

Three Levels of Automation: From Item-Level to Full Scale

1. Item-by-Item Processing: Smart AI Transcription and Spotting, Perfect for High-Quality Editorial Workflows

The first stage of subtitling automation focuses on individual asset processing through Limecraft’s user-friendly web interface. This approach is ideal for organisations that require a balance between speed and editorial precision, typically when dealing with premium content such as documentaries, drama, or magazine-style programming, where the nuance of dialogue and stylistic subtitling conventions are paramount.

Here’s how it works in practice: you simply drag and drop a video file into the Limecraft workspace, select the relevant subtitle language, and pick the preferred subtitle preset, which contains spotting and formatting rules tailored to your broadcast or brand style guide.

1.1 Automation, with Human Oversight

Behind the scenes, Limecraft’s Speechmatics-powered ASR generates highly accurate transcripts, benefitting from advanced AI models trained on broadcast-grade audio, currently supporting more than 100 languages and counting. Features such as custom dictionaries and script processing can be enabled to automatically handle specific terminology, names, or industry jargon.

Following transcription, Limecraft’s AI subtitling engine converts the transcript into subtitles according configurable spotting rules. These rules – aligned with industry standards such as the BBC Subtitle Guidelines or the Nordic Model – control everything from:

• Reading speed, ensuring viewers can comfortably follow subtitles,
• Character count per line, often 38–42 characters for TV, down to 27 characters for social media vertical formats,
• The number of frames between two consecutive subtitles,
• Smart sentence splitting, avoiding awkward breaks mid-sentence,
• Shot-aware timing, aligning subtitle in/out points with scene changes to avoid visual stutter.

The result? Subtitles that require minimal post-editing, reducing average subtitling times by at least 80% or more, while maintaining full editorial control.

1.2 Editorial Efficiency Gains

This method is particularly effective for:

• Broadcasters, balancing accessibility compliance with editorial standards,
• Production companies, seeking quick turnaround without sacrificing quality,
• Corporate comms, producing internal videos or external thought leadership pieces.

Many broadcasters use this level of automation daily, combining editorial judgment with technological efficiency, ensuring subtitles meet internal quality standards without the historical overhead of fully manual subtitling processes.

2. Workflow Integration: API-Enabled Scale for Complex Media Operations

As organisations scale their operations, handling dozens or hundreds of media assets per week, manually uploading files becomes inefficient. This is where Limecraft’s API-accessible subtitling service unlocks the next level of automation maturity.

With direct integration into media asset management (MAM), production asset management (PAM), or content delivery systems, Limecraft’s flexible REST API allows broadcasters and media organisations to:

• Automatically upload and register media assets for processing,
• Configure subtitling parameters via API calls, including language selection, subtitle presets, and spotting rule profiles,
• Initiate transcription and subtitling workflows programmatically, with or without expert in the loop,
• Monitor status updates, retrieving real-time feedback on the progress of subtitling,
• Export completed subtitle files in the format required by distribution partners (SRT, EBU-TT-D, STL, etc.)

2.1 Reducing Operational Bottlenecks

This workflow is a significant productivity boost for access services teams, post-production houses, news desks, and Language Service Providers who need to:

• Eliminate ‘last mile’ subtitling bottlenecks in content delivery workflows,
• Process large volumes of short-form with the shortest possible turn-around time, or
• Avoid manual handovers between systems in general.

By integrating Limecraft directly into their content pipeline, teams like ITV Access Services have cut their processing time for standard programming in half, reducing the time from ingest to delivery from 8 hours per hour of content to just 4.

2.2 Use Cases in Real Workflows

This API-based automation is particularly effective in scenarios where:

• Daily news and entertainment programming requires fast turnaround, with editorial QC,
• Regional language subtitling or multiple subtitle tracks need to be processed concurrently,
• Archive content is being modernised, applying subtitles to existing content at scale.

The ability to orchestrate subtitling as part of a broader content supply chain significantly reduces administrative effort and turnaround time, while maintaining key control points for verification and customisation.

2.3 Case Study: SVT’s Path to Full Automation

A standout example is SVT (Swedish public broadcaster), who transitioned from traditional subtitling to a fully integrated AI-driven model, processing:

• 500+ hours of content monthly,
• 7500 items per month, supporting over 1200 named users,
• Saving an estimated 5000 manual working hours monthly, equivalent to millions in cost savings

By embedding Limecraft’s AI spotting directly into their Avid MediaCentral UX production environment, SVT achieved single-click subtitle generation, enabling journalists to subtitle their own segments without further training or delay.

3. Full Process Automation: End-to-End Subtitling for Massive Scale and Faster-than-Real-Time Turnaround

At the highest level of automation maturity, organisations can achieve zero-touch subtitling, fully automating both the ingestion and delivery of subtitles using serverless infrastructure and cloud-native tools.

This is the chosen model for high-volume environments such as:

• Newsrooms, processing daily bulletins and breaking news packages,
• Sports rights holders, generating thousands of highlight clips during tournaments,
• Social media production hubs, creating snackable content on tight deadlines,

3.1 Hands-off and Lights-out Automation via AWS S3

Limecraft supports AWS S3-based workflows, allowing customers to simply drop files into an S3 bucket, where a Limecraft-deployed Lambda function detects the file, categorises it based on path or metadata, and triggers an automated pipeline:

• Ingest the video file into Limecraft Flow,
• Trigger automatic transcription and subtitle spotting using pre-set configurations,
• Validate for AI confidence scores or QC thresholds,
• Return subtitle files or proxy videos with burnt-in subtitles back to S3 for downstream distribution.

This process runs 24/7, requires no manual oversight, and can scale elastically with workload. IMG’s media factory for FIFA World Cup coverage used this approach to produce over 30000 files to the aggregate of 1000 hours of content in less than a month, meeting strict deadlines while maintaining broadcast quality standards.

3.2 Strategic Impact: Driving Efficiency and Accessibility

This level of automation transforms subtitling from an operational cost to a strategic enabler:

• Accelerating publishing speeds across digital platforms,
• Ensuring regulatory compliance at scale,
• Improving search discoverability via subtitle-enriched metadata,
• Guaranteeing accessibility for all audiences, even in fast-paced editorial environments.

For media companies facing increasing volumes and tighter deadlines, full subtitling automation ensures scalability without proportionally increasing headcount, freeing editorial staff to focus on creativity rather than compliance.

What’s Next: The Roadmap for AI Subtitling

As we continue to innovate, several new features are on the near horizon:

• Speaker identification using dashes or hyphens will become standard in the upcoming 2025.5 release, improving readability and compliance with style guides.
• Multi-lingual transcription will make it easier to process multilingual content, catering to international broadcasters and OTT services.
• Continuous improvements in edit-aware spotting and syntactic segmentation will further reduce post-editing effort, approaching true human-level readability out of the box.

Ready to Transform Your Subtitling Workflow?

Whether you are just starting with AI-assisted subtitling or you’re ready to scale to thousands of hours per month, Limecraft offers the tools to transform your subtitling operations.

💬 Reach out to us to discuss your requirements or book a live demo of Limecraft Flow.

Let’s make subtitling effortless – at any scale.