extractFrame abstract method
The decoded pixels of source at frameIndex (in the source's own
frame space), scaled to exactly width x height.
The caller pins the output size (from a prior probe) so the returned
RawFrame always holds width * height * 4 bytes — deterministic and
directly compositable. Pass decoder to name the decoder the source needs
(libvpx-vp9 for VP9 with alpha); leave it null to let the backend pick.
Throws a FluvieRenderException (or its FluvieEncodeException subtype)
when the source or frame cannot be extracted.
Implementation
Future<RawFrame> extractFrame(
Uri source,
int frameIndex, {
required int width,
required int height,
String? decoder,
});