resolveAudioMix function

ResolvedAudioMix resolveAudioMix({ required Video video, required int fps, int totalFrames = 0, GenerativeResolver? generative, })

Resolves video's declared Audio tracks into an encoder-neutral ResolvedAudioMix for a non-FFmpeg encoder (such as fluvie_mobile_encoder).

It collects the tracks in deterministic declaration order and resolves every track's delay, trim, gain, and fades against fps and the totalFrames window — the same timing math the FFmpeg mix uses, so an on-device render matches a desktop render. Pure and synchronous: it reads no files, so each track keeps its authored ResolvedAudioTrack.source; the custom encoder materializes those sources itself. The default render path never calls this; it is the opt-in seam for custom encoders. A video with no audio yields an empty mix.

Implementation

ResolvedAudioMix resolveAudioMix({
  required Video video,
  required int fps,
  int totalFrames = 0,
  GenerativeResolver? generative,
}) {
  final scope = TimeScopeData(fps: fps, startFrame: 0, durationFrames: totalFrames);
  final tracks = <ResolvedAudioTrack>[
    for (final track in collectAudioTracks(video, generative: generative))
      resolveAudioTrack(track, fps: fps, scope: scope),
    // A clip's embedded audio (including a generated video's, for example Veo 3)
    // plays where the clip plays: delayed to its scene start and trimmed to the
    // scene window (so sequential clips don't bleed).
    for (final plan in collectClipAudioPlans(video.scenes, fps, generative: generative))
      _clipAudioTrack(plan, fps, scope),
  ];
  return ResolvedAudioMix(tracks: tracks);
}