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title: Reference description: Accurate, structured facts: every option and its default, every job field, every result, the release artifacts, and the limits. date: 2026-06-26 tags: [reference] authors: [Matt Cockayne matt@phpboyscout.uk]

Reference

Information-oriented, accurate facts about afmpeg's surfaces. Reference is a promise of accuracy: every documented option, default and error here matches the implementation.

The pages

  • Runtime options: every option afmpeg.New accepts: what it does, what it defaults to, and what happens when it is wrong or omitted. Start here for "what is the default memory cap" and "how do I turn the invocation timeout off".
  • Command, Input, Output and FrameJob fields: every field of the job types, the builder option that sets it, and the combinations rejected before the engine sees them.
  • Results, probes and progress values: everything afmpeg hands back, field by field, including when a field is zero rather than meaningful.
  • Engine releases: variants, profiles, exact asset filenames, provenance keys, trust keys, cache locations, and which engine versions a given afmpeg accepts.
  • The guest filesystem: how paths resolve, which locations are synthetic, which operations are supported, and what returns ENOSYS.
  • Limitations: what afmpeg does not do, will not do, or does on only one backend.

Go API

The per-symbol Go API reference is not duplicated here. It is authoritatively generated from the source and published on the package registry:

➡️ pkg.go.dev/gitlab.com/phpboyscout/afmpeg

The pages above carry what a symbol list does not: defaults, failure modes, cross-cutting constraints, and the artifact naming contract with the engine project.

Elsewhere

  • Errors: the sentinel-error catalogue lives under Explanation › Components › Errors, beside the error-handling convention it belongs to.
  • Engine capability tables: which codecs, filters and formats each profile carries is the ffmpeg-wasi project's reference, not this one. afmpeg documents which artifact it loads; ffmpeg-wasi documents what is inside it.
  • CLI: there is none. cmd/afmpeg-bench in this repository is a benchmark harness, not a general-purpose tool, and a user-facing CLI remains deferred.