Module engine 

The compression engine contract and shared types.

Key architectural decision: core is designed around the Engine interface even while there is exactly one engine (media/ffmpeg). This lets us plug in images/PDF/office later without rewriting the skeleton.

Principle: Engine::plan is a pure, testable function (bitrate math); side effects are isolated in Engine::run.

Modules

media

Media engine v0.1: video + audio via ffmpeg (external process).

Structs

AudioSpec

Audio encoding parameters (absent means drop the track).

CaptureMeta

Capture metadata read from the source’s container tags. iPhone videos keep these as com.apple.quicktime.* keys; others use plain location / make / model / creation_time.

EncodePlan

The encode plan — the result of Engine::plan. Usable for --dry-run.

EncodeSpec

The full encode recipe.

MediaInfo

Source file metadata — the result of Engine::probe.

Outcome

The execution result — the result of Engine::run.

ShrinkOpts

Compression options passed to the engine — the decoded form of the flags.

VideoSpec

Video encoding parameters.

Enums

EngineError

Engine errors.

Hdr

HDR transfer function of a source video.

SizeGoal

What the user wants in terms of size.

Constants

MIN_SAVING

A quality-mode re-encode has to save at least this share of the source to be worth it; below that the original is kept. A minutes-long 4K encode for a 1 % saving isn’t a compression — just a generation of quality loss.

Traits

Engine

The compression engine contract. The one v0.1 implementation is media::MediaEngine.

Functions

not_worth_it

Whether a result of expected bytes isn’t worth producing for a source of source bytes (saves less than MIN_SAVING). The guard, dry runs and UI previews all ask this, so a preview and the run agree.