Fixed audio embed videos running longer than the audio in AudioEmbed.py

Backend/AudioEmbed.py

@@ -25,6 +25,9 @@ ApplicationDirectory = Path(__file__).resolve().parent
 # The browser-tab icon (Frontend/public/Icons), when the audio has no cover art.
 IconPath = ApplicationDirectory.parent / "Frontend" / "dist" / "Icons" / "Icon.png"
 FrameSize = 480
+# Part of every cache key: bump it when the videos change, so old ones
+# aren't served (2: cut to the audio's exact length).
+EncodingVersion = 2
 EncodeTimeout = 600  # seconds
 
 _Locks: dict[str, threading.Lock] = {}
@@ -65,10 +68,19 @@ def _BackgroundColour() -> str:
 
 def _CachePath(AudioPath: Path) -> Path:
     Stat = AudioPath.stat()
-    Key = hashlib.sha256(f"{AudioPath}|{Stat.st_size}|{Stat.st_mtime_ns}".encode()).hexdigest()[:32]
+    Key = hashlib.sha256(f"{EncodingVersion}|{AudioPath}|{Stat.st_size}|{Stat.st_mtime_ns}".encode()).hexdigest()[:32]
     return GetDataDirectory() / "EmbedCache" / f"{Key}.mp4"
 
 
+def _AudioDuration(AudioPath: Path) -> float | None:
+    try:
+        Result = subprocess.run(["ffprobe", "-v", "error", "-show_entries", "format=duration", "-of", "csv=p=0",
+                                 str(AudioPath)], capture_output=True, text=True, timeout=60)
+        return float(Result.stdout.strip())
+    except (OSError, subprocess.SubprocessError, ValueError):
+        return None
+
+
 def _ExtractCoverArt(AudioPath: Path, Target: Path) -> bool:
     """Writes the file's own cover art (if it has any) to Target as a PNG."""
     try:
@@ -95,11 +107,17 @@ def _Encode(AudioPath: Path, Target: Path) -> None:
     # A non-square cover gets bars in the theme's background colour.
     Fit = (f"scale={FrameSize}:{FrameSize}:force_original_aspect_ratio=decrease:flags={Scaling},"
            f"pad={FrameSize}:{FrameSize}:(ow-iw)/2:(oh-ih)/2:color=0x{Background},format=yuv420p")
+    # The picture loops forever, so the video is cut to the audio's length.
+    # -shortest alone overshoots: libx264 buffers ~40 frames ahead, which at
+    # one frame a second left the picture running 40+ seconds past the
+    # audio, and Discord wouldn't play that.
+    Duration = _AudioDuration(AudioPath)
+    Length = ["-t", f"{Duration:.3f}"] if Duration else []
     Command = [
         "ffmpeg", "-y", "-loglevel", "error", *Picture, "-i", str(AudioPath),
-        "-map", "0:v:0", "-map", "1:a:0", "-vf", Fit, "-r", "1",
+        "-map", "0:v:0", "-map", "1:a:0", "-vf", Fit, "-r", "1", "-g", "10",
         *_VideoEncoder(),
-        "-c:a", "aac", "-b:a", "192k", "-shortest", "-movflags", "+faststart", str(Partial),
+        "-c:a", "aac", "-b:a", "192k", "-shortest", *Length, "-movflags", "+faststart", str(Partial),
     ]
     try:
         subprocess.run(Command, check=True, capture_output=True, timeout=EncodeTimeout)