fix(replay): Skip MediaMuxer stop when no samples were written

runningcode · runningcode · commit f2ea2f020fdb · 2026-07-23T12:32:56.000+02:00
MediaMuxer.stop() throws IllegalStateException when the muxer was started
but no sample was ever written to its track. SimpleMp4FrameMuxer.release()
only guarded against the never-started case, so a started-but-empty muxer
made release() throw.

Because release() runs from SimpleVideoEncoder's finally block, that throw
propagates out to createVideoOf, which treats release() as safe cleanup;
the encoder is left dangling and the orphan video file is never deleted.

Only call stop() when at least one sample was written; muxer.release() on a
started-but-not-stopped muxer is safe.
diff --git a/sentry-android-replay/src/main/java/io/sentry/android/replay/video/SimpleMp4FrameMuxer.kt b/sentry-android-replay/src/main/java/io/sentry/android/replay/video/SimpleMp4FrameMuxer.kt
@@ -67,9 +67,9 @@ internal class SimpleMp4FrameMuxer(path: String, fps: Float) : SimpleFrameMuxer
   }
 
   override fun release() {
-    // stop() throws if the muxer was never started (e.g. no frame was ever muxed), so we guard it
-    // to ensure release() is always reached and the underlying resources are freed
-    if (started) {
+    // stop() throws unless the muxer was started AND at least one sample was written, so we guard it
+    // to ensure muxer.release() is always reached and the underlying resources are freed
+    if (started && videoFrames > 0) {
       muxer.stop()
     }
     muxer.release()

Original file line number	Diff line number	Diff line change
`@@ -67,9 +67,9 @@ internal class SimpleMp4FrameMuxer(path: String, fps: Float) : SimpleFrameMuxer`
`67`	`67`	`}`
`68`	`68`
`69`	`69`	`override fun release() {`
`70`		`- // stop() throws if the muxer was never started (e.g. no frame was ever muxed), so we guard it`
`71`		`- // to ensure release() is always reached and the underlying resources are freed`
`72`		`- if (started) {`
	`70`	`+ // stop() throws unless the muxer was started AND at least one sample was written, so we guard it`
	`71`	`+ // to ensure muxer.release() is always reached and the underlying resources are freed`
	`72`	`+ if (started && videoFrames > 0) {`
`73`	`73`	`muxer.stop()`
`74`	`74`	`}`
`75`	`75`	`muxer.release()`