• Note: This is an adaptation for iOS of the sample code project associated with WWDC20 session 10011: Authoring Fragmented MPEG-4 with AVAssetWriter.

To run the iOS project

• Select the iOSWriter schema and run it.

The segment generation will start after the view controller is loaded and once it's done, it'll show you a UIActivityController to share the output folder.

Notice that the input video is 10 seconds long but the output is only 6 seconds long.

To run the macOS project

Before you run the sample code project in Xcode:

1. Edit the shared scheme called fmp4Writer.
2. Open the Run action.
3. Replace the <path to movie file on disk> argument with the path to a movie file on your local hard drive.
4. Replace the <path to output directory> argument with your desired output directory; for example ~/Desktop/fmp4writer/.

Changes for making it work in iOS

• Use an asset from the app bundle instead of reading the asset from the file system.
• Copy the code from main.swift file to the ViewController.swift
• In videoCompressionSettings, change the value of the key kVTCompressionPropertyKey_ProfileLevel from kVTProfileLevel_H264_High_4_2 to kVTProfileLevel_H264_High_4_1.