What Is a Video Processing API?
A video processing API is a web service that lets you merge, cut, watermark, convert, and manipulate video files programmatically — without installing FFmpeg, managing GPU servers, or writing codec-level code. You send an HTTP request with your video file and processing parameters, and the API returns the processed output. VideoComposer's API handles the infrastructure so you focus on the product logic.
This guide covers the core use cases, code examples, and architecture decisions developers need when building video processing into an application.
Why Use a Video Processing API Instead of DIY FFmpeg?
Building your own video processing stack is a significant engineering investment. FFmpeg is powerful, but running it at scale means managing server capacity, codec compatibility, format normalization, and error handling across dozens of edge cases.
A video processing API abstracts all of that. You get a REST endpoint, a file upload, and a processed result — without provisioning a single server.
Common reasons developers choose an API over DIY:
- No FFmpeg installation, configuration, or version management
- No GPU or compute server provisioning
- Codec and format compatibility handled by the API
- Predictable cost per operation versus variable cloud compute costs
- Faster time to ship — integrate in hours, not weeks
The VideoComposer API is built for exactly this use case: developers who need reliable video processing without the infrastructure burden.
Core Use Cases for a Video Processing API
Automated Video Trimming
Cut video clips to exact timestamps without user intervention. Useful for:
- Trimming user-uploaded content to platform length limits
- Extracting highlight clips from longer recordings
- Auto-cutting silence or dead air from podcast video exports
Batch Video Merging
Join multiple clips into a single file as part of an automated pipeline. Useful for:
- Combining episode segments after recording
- Stitching together automated video reports
- Merging short-form clips for compilation content at scale
Watermarking at Scale
Apply logo overlays or text watermarks to videos programmatically. Useful for:
- Branding all uploaded content before distribution
- Adding timestamps or metadata overlays to surveillance or training footage
- Protecting content with copyright attribution
Format Conversion
Convert videos between formats (MP4, WebM, MOV, etc.) as part of an ingestion or delivery pipeline. Useful for:
- Normalizing user uploads to a single delivery format
- Converting source files for CDN delivery optimization
- Re-encoding for platform-specific requirements (YouTube, TikTok, etc.)
Subtitle Burn-In
Embed SRT, VTT, or ASS subtitle tracks directly into the video file (hard subtitles). Useful for:
- Ensuring captions are visible on platforms that do not support external subtitle tracks
- Burning in localized subtitles for international distribution
- Accessibility compliance for video content
API Usage — Code Examples
The VideoComposer API uses standard HTTP requests with multipart form uploads. All endpoints are documented at /developers. The examples below show the conceptual request structure for each core operation.
Merge Videos via API
curl -X POST https://videocomposer.io/api/v1/merge \ -H "Authorization: Bearer YOUR_API_KEY" \ -F "files[]=@clip1.mp4" \ -F "files[]=@clip2.mp4" \ -F "files[]=@clip3.mp4" \ -F "output_format=mp4"
The API processes the clips in the order they are submitted and returns a download URL for the merged output. For large files, the response includes a job ID for async polling.
Cut Video via API
curl -X POST https://videocomposer.io/api/v1/cut \ -H "Authorization: Bearer YOUR_API_KEY" \ -F "file=@source.mp4" \ -F "start=00:00:10" \ -F "end=00:01:30" \ -F "output_format=mp4"
Timestamps use HH:MM:SS format. The API extracts the segment between start and end and returns the trimmed clip. Sub-second precision is supported using HH:MM:SS.mmm.
Add Watermark via API
curl -X POST https://videocomposer.io/api/v1/watermark \ -H "Authorization: Bearer YOUR_API_KEY" \ -F "file=@video.mp4" \ -F "watermark=@logo.png" \ -F "position=bottom-right" \ -F "opacity=0.8"
Supported positions: top-left, top-right, bottom-left, bottom-right, center. Opacity accepts values from 0.0 (invisible) to 1.0 (fully opaque).
Convert Format via API
curl -X POST https://videocomposer.io/api/v1/convert \ -H "Authorization: Bearer YOUR_API_KEY" \ -F "file=@recording.mov" \ -F "output_format=mp4" \ -F "quality=high"
Supported output formats include mp4, webm, mov, and avi. The quality parameter accepts low, medium, and high — higher quality means larger output file size.
Burn Subtitles via API
curl -X POST https://videocomposer.io/api/v1/subtitles/burn \ -H "Authorization: Bearer YOUR_API_KEY" \ -F "file=@video.mp4" \ -F "subtitles=@captions.srt" \ -F "font_size=24" \ -F "position=bottom"
Accepted subtitle formats: SRT, VTT, ASS. The burned subtitles are embedded permanently into the video stream and visible on any player without subtitle track support.
Build Your Own vs. VideoComposer API
Before committing to an API integration, teams often evaluate whether to build internally using FFmpeg or a similar library. Here is a direct comparison across the dimensions that matter most:
| Feature | DIY / FFmpeg | VideoComposer API |
|---|---|---|
| Setup time | Days to weeks | Hours |
| Infrastructure management | You manage servers and scaling | Fully managed |
| Codec support | Manual configuration per codec | Handled automatically |
| Format compatibility | Varies by FFmpeg version | Normalized across all inputs |
| Subtitle support | Complex filter graph required | SRT, VTT, ASS supported natively |
| Async job processing | Build it yourself | Built-in with polling endpoints |
| Cost model | Variable compute costs | Per-operation pricing |
| Error handling | Implement from scratch | Standardized API errors |
| Maintenance | Ongoing — codec updates, server patches | Zero — maintained by VideoComposer |
| Time to first result | Days of integration work | Under an hour |
The DIY route makes sense when you need extremely specialized codec behavior, have an existing infrastructure team, or require on-premise processing for compliance reasons. For most product teams, the VideoComposer API is faster and cheaper when total engineering cost is factored in.
Integration Patterns
Webhook-Based Async Processing
For long video files, use the async mode with a webhook to receive the result:
curl -X POST https://videocomposer.io/api/v1/merge \ -H "Authorization: Bearer YOUR_API_KEY" \ -F "files[]=@part1.mp4" \ -F "files[]=@part2.mp4" \ -F "async=true" \ -F "webhook_url=https://yourapp.com/webhooks/video-complete"
The API returns a job_id immediately. When processing is complete, VideoComposer sends a POST to your webhook_url with the job result and download URL.
Polling for Job Status
If webhooks are not available in your environment, poll the job status endpoint:
curl https://videocomposer.io/api/v1/jobs/JOB_ID \ -H "Authorization: Bearer YOUR_API_KEY"
The response includes a status field: queued, processing, complete, or failed. Poll every 5-10 seconds until status is complete.
Chained Operations
Chain multiple operations in a pipeline — for example, cut first, then watermark:
# Step 1: Cut the clip curl -X POST https://videocomposer.io/api/v1/cut \ -H "Authorization: Bearer YOUR_API_KEY" \ -F "file=@raw.mp4" \ -F "start=00:00:05" \ -F "end=00:02:00" \ > cut_result.json # Step 2: Watermark the trimmed clip using the URL from step 1 TRIMMED_URL=$(cat cut_result.json | jq -r '.download_url') curl -X POST https://videocomposer.io/api/v1/watermark \ -H "Authorization: Bearer YOUR_API_KEY" \ -F "file_url=$TRIMMED_URL" \ -F "watermark=@logo.png" \ -F "position=bottom-right"
The API accepts either a file upload or a file_url parameter pointing to a previously processed result. This makes chaining operations straightforward without intermediate file storage on your servers.
API Rate Limits and Scaling
The VideoComposer API is designed for production use at scale. Rate limits and concurrent job quotas vary by plan. For projects requiring high-volume batch processing — for example, processing hundreds of clips per hour — see the pricing page for plan details and enterprise options.
For comparison with the interactive tools, you can also explore the browser-based tools to prototype before committing to API integration:
- Merge videos online — browser-based merge tool
- Cut MP4 online — browser-based trim tool
- Add watermark to video — browser-based watermark tool
- Video converter — browser-based format converter
Frequently Asked Questions
What programming languages does the VideoComposer API support?
The VideoComposer API is a standard REST API that works with any language that can make HTTP requests — Python, Node.js, Ruby, Go, PHP, Java, and others. The examples in this guide use curl for clarity, but the same requests translate directly to any HTTP client library.
Do I need to manage FFmpeg or video codecs?
No. That is the primary benefit of using the VideoComposer API. All codec selection, format normalization, and FFmpeg configuration is handled on the API side. You send a file and parameters — the API returns a processed result.
Can the API handle large video files?
Yes. The async mode with webhook delivery is designed for large files that take longer to process. You submit the job, receive a job ID, and get notified when processing is complete. This prevents timeout issues common with synchronous HTTP requests on large files.
Is there a free tier for API access?
API access is available on paid plans. See the pricing page for current plan details. The browser-based tools at /tools/merge-videos and /tools/mp4-cutter are free to use without an API key if you need to test the processing quality before integrating.
What subtitle formats does the API support?
The API supports SRT, VTT, and ASS subtitle formats for both merge operations (where subtitle cues are re-timed automatically) and subtitle burn-in operations (where the text is embedded permanently into the video stream).
How do I get started with the API?
Visit the developers page for full API documentation, authentication setup, and endpoint reference. The documentation includes request and response schemas, error codes, and examples for all supported operations.
Can I merge videos with different resolutions via the API?
Yes. The API normalizes clips with different resolutions during the merge operation. You can control the output resolution via parameters, or allow the API to default to the highest resolution among the input clips.
Next Steps
The VideoComposer API is built for developers who need reliable, scalable video processing without the overhead of managing their own infrastructure. Whether you need to merge clips, cut segments, burn subtitles, or watermark at scale, the API handles the heavy lifting.
- Start with the docs — Full API reference is at /developers
- Test interactively first — Use the merge tool or cutter tool to validate results before integrating
- Check pricing — API plans are on the pricing page
- Explore more guides — The blog has additional tutorials on video processing workflows