Frame extension (e.g. 'png', 'jpg', 'exr') for ffmpeg's input pattern.
Human-readable label for toasts ("PNG", "EXR").
Total bytes streamed (used in toasts when saving to disk).
ffmpeg script body to attach as encode_video.sh.
Suggested filename for the in-memory fallback download.
Show a toast (panel-supplied so this module stays UI-agnostic).
Download a blob (panel-supplied).
OptionalonOptional UI hook called before the (potentially slow) finalize step.
OptionalsignalOptional abort signal. If aborted mid-finalize, finalize() routes to internal abort cleanup (end stream, abort writable, drop chunks) and does NOT call showToast / downloadBlob — the panel is responsible for cancel UX.
Frame count actually captured (excludes failures).