To extract audio from an MP4 video on an iPad's Safari browser, we'll create a web app that uses the Web Audio API and MediaRecorder API. Here's a step-by-step solution:
```html
Audio Extractor for iPad
```
### Key Features:
1. **iPad Safari Compatibility**:
- Uses MediaRecorder API with AAC codec (`audio/mp4; codecs="mp4a.40.2"`)
- Requires iOS 14.5+ for full MediaRecorder support
- Touch-friendly interface with large buttons
2. **Audio Extraction Process**:
- User selects an MP4 video file
- Video is loaded in a hidden player
- Audio is routed through Web Audio API
- MediaRecorder captures audio stream
- Output is saved as M4A (AAC) file
3. **User Experience**:
- Progress bar shows extraction status
- Cancel button to stop extraction
- Download link appears when complete
- Error handling for unsupported formats
- Clean, iOS-style interface
4. **Technical Implementation**:
- Uses `createMediaElementSource` to access video audio
- `MediaStreamDestination` creates recordable stream
- MediaRecorder captures AAC audio in MP4 container
- Blob URL generation for download
### Usage Instructions:
1. Open the HTML file in Safari on iPad
2. Tap "Select MP4 Video" to choose a video file
3. Tap "Extract Audio" to start the process
4. Wait for extraction to complete (progress bar will show status)
5. Tap "Download Audio" to save the M4A file
### Limitations:
1. Requires iOS 14.5 or later
2. Only supports MP4 videos with AAC audio
3. Extraction happens in real-time (video plays at normal speed)
4. Large files may cause memory issues on older devices
This solution provides a complete, self-contained HTML page that works directly in Safari on iPad without requiring any server-side processing or external libraries.