Fix: map 0:v:0 explicitly in transcode and mux to skip data/timecode streams

app.py

@@ -177,7 +177,8 @@ def _transcode_for_browser(video_path: str) -> str:
             kwargs["audio_bitrate"] = "128k"
         else:
             kwargs["an"] = None
-        ffmpeg.input(video_path).output(out_path, **kwargs).run(
+        # map 0:v:0 explicitly to skip non-video streams (e.g. data/timecode tracks)
+        ffmpeg.input(video_path).output(out_path, map="0:v:0", **kwargs).run(
             overwrite_output=True, quiet=True
         )
         return out_path
@@ -315,6 +316,7 @@ def mux_video_audio(silent_video: str, audio_path: str, output_path: str,
             ffmpeg.input(silent_video),
             ffmpeg.input(audio_path),
             output_path,
+            map=["0:v:0", "1:a:0"],
             vcodec="libx264", preset="fast", crf=18,
             pix_fmt="yuv420p",
             acodec="aac", audio_bitrate="128k",