Media3 Transformer Editing

Trigger

Use for media editing/export flows: trim, transcode, clip export, composition, progress, cancellation, or media3-transformer.

Rules

• Do not mix editing/export ownership with playback ownership.
• Pin Media3 to 1.10.1 through the version catalog.
• Keep Transformer code in Android source sets; expose KMP-safe job state upward.
• Model export as a job with input URI, output path, progress, cancellation, failure reason, and cleanup.
• Check codec/container support before promising a transformation.
• Run long exports outside composables and survive Activity recreation.
• Store only safe, scoped output URIs; respect Android storage rules.

Example

media3-transformer = { module = "androidx.media3:media3-transformer", version.ref = "media3" }

data class ExportState(
    val progress: Float,
    val isRunning: Boolean,
    val error: String?
)

Do Not

• Do not block the UI thread during export.
• Do not assume every input codec can be exported on every device.
• Do not leave partial output files after cancellation or failure.

Related

• media3-video-effects-lottie-muxer
• media3-inspector-metadata-thumbnails
• media3-workmanager-offline-ops

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: sunnat629
• Source: sunnat629/android-media-pack
• License: Apache-2.0

Install and usage instructions live in the source repository linked above.