Scene player fixes and improvements (#5340)

* Don't log context canceled error during live transcode
* Pause live transcode if still scrubbing
* Debounce loading live transcode source to avoid multiple ffmpeg instances
* Don't start from start or resume time if seeking before playing
* Play video when seeked before playing

pkg/ffmpeg/stream_transcode.go

@@ -1,6 +1,7 @@
 package ffmpeg
 
 import (
+	"context"
 	"errors"
 	"io"
 	"net/http"
@@ -230,7 +231,10 @@ func (sm *StreamManager) ServeTranscode(w http.ResponseWriter, r *http.Request,
 	handler, err := sm.getTranscodeStream(lockCtx, options)
 
 	if err != nil {
-		logger.Errorf("[transcode] error transcoding video file: %v", err)
+		// don't log context canceled errors
+		if !errors.Is(err, context.Canceled) {
+			logger.Errorf("[transcode] error transcoding video file: %v", err)
+		}
 		w.WriteHeader(http.StatusBadRequest)
 		if _, err := w.Write([]byte(err.Error())); err != nil {
 			logger.Warnf("[transcode] error writing response: %v", err)