From ccfaeff143bba1fa620d77a032e2edf8039c3e22 Mon Sep 17 00:00:00 2001
From: pat-e <pat-e@pat-e.net>
Date: Mon, 22 Sep 2025 08:16:17 +0200
Subject: [PATCH] Replacement of the audio normalization in mkvopusenc

---
 MkvOpusEnc.py              | 23 +++++++++++++++++++----
 README_MkvOpusEnc.md       |  3 +--
 README_av1_opus_encoder.md |  1 -
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/MkvOpusEnc.py b/MkvOpusEnc.py
index 3e2fec1..8b72afe 100644
--- a/MkvOpusEnc.py
+++ b/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
diff --git a/README_MkvOpusEnc.md b/README_MkvOpusEnc.md
index 9a844d0..d057a62 100644
--- a/README_MkvOpusEnc.md
+++ b/README_MkvOpusEnc.md
@@ -12,7 +12,7 @@
     *   Re-encodes all other audio formats (DTS, AC3, TrueHD, FLAC, etc.) to Opus.
 *   **Advanced Downmixing:** Includes an optional `--downmix` flag that converts multi-channel audio (5.1, 7.1) to stereo using a dialogue-boosting formula.
 *   **Audio Normalization:** Uses `SoX` to normalize audio levels for a consistent listening experience.
-*   **Metadata Preservation:** Carefully preserves audio track metadata such as titles, language tags, and delay/sync information.
+*   **Audio Normalization:** Uses `ffmpeg`'s two-pass `loudnorm` filter (EBU R 128) to normalize audio levels for a consistent listening experience.
 *   **Detailed Logging:** Creates a separate, detailed log file for each processed MKV in the `conv_logs/` directory, capturing the full terminal output and conversion details for easy review.
 *   **File Organization:** Automatically moves the original source files to an `original/` directory and the newly processed files to a `completed/` directory, keeping your workspace clean.
 *   **Cross-Platform:** As a Python script using common command-line tools, it is designed to work on Windows, macOS, and Linux.
@@ -24,7 +24,6 @@ The following command-line tools must be installed and available in your system'
 *   `ffmpeg`
 *   `ffprobe`
 *   `mkvmerge`
-*   `sox_ng`
 *   `opusenc`
 *   `mediainfo`
 
diff --git a/README_av1_opus_encoder.md b/README_av1_opus_encoder.md
index 90b3e86..7c6493c 100644
--- a/README_av1_opus_encoder.md
+++ b/README_av1_opus_encoder.md
@@ -24,7 +24,6 @@ The following command-line tools must be installed and available in your system'
 *   `ffprobe`
 *   `mkvmerge`
 *   `mkvpropedit`
-*   `sox_ng`
 *   `opusenc`
 *   `mediainfo`
 *   `av1an`