How do I integrate a video encoding API with S3 or another storage bucket?

To integrate a video encoding API with S3 or another storage bucket, the usual pattern is:

1. Upload the source video to storage
2. Send the encoder a reference to that file
3. Have the encoder write outputs back to storage
4. Use webhooks or polling to track job status

Common architecture

Option A: Encoder pulls from S3

• You upload input.mp4 to S3.
• Your app creates an encoding job and passes the S3 URL or object reference to the API.
• The encoder fetches the file from S3, processes it, and uploads results back to S3.

Option B: App uploads directly to the encoding service

• You send the file to the encoding API directly.
• The service stores and processes it.
• Outputs are copied to S3 afterward, or the service stores them in its own CDN/storage.

Option C: Pre-signed URLs

• Your backend generates a pre-signed S3 URL for secure upload.
• The client uploads the file directly to S3.
• Your backend tells the encoder where the source file is.

This is often the best approach for large video files.

---

Typical flow with S3

1. Upload video to S3

Use a pre-signed URL so users can upload directly from the browser/app.

Example flow:

• Client asks your backend for an upload URL
• Backend returns a pre-signed PUT URL
• Client uploads the file to S3

2. Create encoding job

Your backend calls the encoding API with:

• input file location
• output settings, like resolution, bitrate, container format
• destination bucket/path for outputs
• callback/webhook URL for job completion

Example payload might include:

{
  "input": "s3://my-bucket/uploads/video.mp4",
  "outputs": [
    {
      "format": "mp4",
      "resolution": "1280x720",
      "destination": "s3://my-bucket/encoded/video-720p.mp4"
    }
  ],
  "webhook_url": "https://api.example.com/encoding-callback"
}

3. Encoder processes and stores outputs

The encoder:

• reads the input from S3
• transcodes it
• uploads the resulting files to S3 or another bucket

4. Receive completion notification

Use:

• webhooks for event-driven updates, or
• polling if the API doesn’t support callbacks

When complete, update your database with:

• job status
• output URLs
• duration/bitrate/thumbnail metadata

---

AWS S3 permissions

The encoding service needs permission to:

• GetObject on the input bucket/path
• PutObject on the output bucket/path

If the service is in your AWS account, use an IAM role.
If it’s external, you may need:

• bucket policies allowing the service’s AWS principal
• temporary pre-signed URLs
• or access via a proxy service you control

---

Security best practices

• Use pre-signed URLs instead of long-lived credentials
• Restrict bucket access to specific prefixes, like uploads/ and outputs/
• Use server-side encryption on S3
• Validate file type and size before encoding
• Set lifecycle rules to delete temporary uploads after processing
• Verify webhook signatures to avoid spoofed callbacks

---

Example implementation pattern

Backend steps

1. Generate pre-signed upload URL
2. Save an upload record in DB
3. Client uploads file to S3
4. Backend submits encoding job with input/output locations
5. Encoder processes file
6. Webhook updates job status
7. App serves output URL or CDN URL

---

If your encoder supports S3 natively

Some APIs allow you to pass:

• S3 bucket
• object key
• AWS region
• IAM role or access credentials

In that case, configuration is usually just:

• input bucket
• output bucket
• permissions
• job parameters

---

If it doesn’t support S3 natively

Use one of these:

• pre-signed GET URL for the input file
• pre-signed PUT URL for the output file
• or your backend acts as a bridge:
  • downloads from S3
  • uploads to the encoding API
  • downloads processed output
  • stores output back to S3

---

Minimal pseudo-flow

Client -> Backend: request upload URL
Backend -> S3: generate pre-signed URL
Client -> S3: upload video
Client -> Backend: notify upload complete
Backend -> Encoder API: create transcode job with S3 input/output
Encoder API -> S3: download input, upload output
Encoder API -> Backend: webhook job complete
Backend -> DB: mark finished

If you want, I can also give you:

• a Node.js example
• a Python example
• an AWS Lambda / S3 / transcoding architecture
• or an example for a specific encoder like Mux, Cloudflare Stream, Bitmovin, AWS MediaConvert, or Zencoder.