The FFmpegEngine half landed in ad2a75d; this is the same gap in
ConcatEngine. Between them, a real native session being asked to stop is
now covered on both FFmpeg paths.
The assertion is the session's return code again, and here that is not
merely the better choice but close to the only one: ConcatEngine does not
delete its output on cancellation at all. Its invokeOnCancellation is
FFmpegKit.cancel and nothing else, where FFmpegEngine's also deletes the
partial. Whether that asymmetry is deliberate is a separate question, so
this asserts what is true of both engines rather than depending on it.
The cancel triggers on SessionState.RUNNING rather than on progress.
ConcatWorker publishes no progress at all, so there is no callback to hang
it on even in principle -- and the conversion side already measured the
deeper reason, that the committed clips outrun a callback-triggered cancel.
The inputs are the mismatched pair on purpose, so ConcatPlanner chooses
REENCODE. A stream copy of two 2 s clips is close to instantaneous and
would leave nothing to interrupt; re-encoding is also the case where a user
would actually reach for Cancel.
Verified on a local API 34 emulator: three runs green at 64/0/0/3, and
replacing invokeOnCancellation's body with an empty block fails this test
and nothing else, with state=COMPLETED rc=0.
Media3Engine's transformer.cancel() is still uncovered and #224 stays open
for it.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
JMR-devandClaude Opus 5