Replacement of the audio normalization in mkvopusenc

MkvOpusEnc.py

@@ -32,7 +32,7 @@ class Tee:
 
 def check_tools():
     """Checks if all required command-line tools are in the system's PATH."""
-    required_tools = ["ffmpeg", "ffprobe", "mkvmerge", "sox_ng", "opusenc", "mediainfo"]
+    required_tools = ["ffmpeg", "ffprobe", "mkvmerge", "opusenc", "mediainfo"]
     print("--- Prerequisite Check ---")
     all_found = True
     for tool in required_tools:
@@ -78,9 +78,24 @@ def convert_audio_track(stream_index, channels, temp_dir, source_file, should_do
     ffmpeg_args.extend(["-c:a", "flac", str(temp_extracted)])
     run_cmd(ffmpeg_args)
 
-    # Step 2: Normalize the track with SoX
-    print("    - Normalizing with SoX...")
-    run_cmd(["sox_ng", "--show-progress", str(temp_extracted), str(temp_normalized), "--temp", str(temp_dir), "loudness", "-18"])
+    # Step 2: Normalize the track with ffmpeg's loudnorm (2-pass)
+    print("    - Normalizing with ffmpeg (loudnorm 2-pass)...")
+    # First pass: Analyze the audio to get loudnorm stats
+    print("      - Pass 1: Analyzing...")
+    result = subprocess.run(
+        ["ffmpeg", "-v", "info", "-i", str(temp_extracted), "-af", "loudnorm=I=-14:LRA=7:tp=-1:print_format=json", "-f", "null", "-"],
+        capture_output=True, text=True, check=True)
+    stats_lines = result.stderr.strip().split('\n')
+    stats_json_str = "".join(stats_lines[-12:]) # The JSON block is the last 12 lines
+    stats = json.loads(stats_json_str)
+
+    # Second pass: Apply the normalization using the stats from the first pass
+    print("      - Pass 2: Applying normalization...")
+    run_cmd([
+        "ffmpeg", "-v", "quiet", "-stats", "-y", "-i", str(temp_extracted), "-af",
+        f"loudnorm=I=-14:LRA=7:tp=-1:measured_i={stats['input_i']}:measured_lra={stats['input_lra']}:measured_tp={stats['input_tp']}:measured_thresh={stats['input_thresh']}:offset={stats['target_offset']}",
+        "-c:a", "flac", str(temp_normalized)
+    ])
 
     # Step 3: Encode to Opus with the correct bitrate
     bitrate = "192k"  # Fallback