347 lines
16 KiB
Python
347 lines
16 KiB
Python
#!/usr/bin/env python3
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"""
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Processes or downmixes an MKV file's audio tracks sequentially using a specific toolchain.
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This script is cross-platform and optimized for correctness and clean output.
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This script intelligently handles audio streams in an MKV file one by one.
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- AAC/Opus audio is remuxed.
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- Multi-channel audio (DTS, AC3, etc.) can be re-encoded or optionally downmixed to stereo.
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- All other streams and metadata (title, language, delay) are preserved.
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"""
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import argparse
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import json
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import shutil
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import subprocess
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import sys
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import tempfile
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from datetime import datetime
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from pathlib import Path
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class Tee:
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def __init__(self, *files):
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self.files = files
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def write(self, obj):
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for f in self.files:
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f.write(obj)
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f.flush()
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def flush(self):
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for f in self.files:
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f.flush()
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def check_tools():
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"""Checks if all required command-line tools are in the system's PATH."""
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required_tools = ["ffmpeg", "ffprobe", "mkvmerge", "opusenc", "mediainfo"]
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print("--- Prerequisite Check ---")
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all_found = True
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for tool in required_tools:
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if not shutil.which(tool):
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print(f"Error: Required tool '{tool}' not found.", file=sys.stderr)
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all_found = False
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if not all_found:
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sys.exit("Please install the missing tools and ensure they are in your system's PATH.")
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print("All required tools found.")
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def run_cmd(args, capture_output=False, check=True):
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"""Helper function to run a command and return its output."""
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process = subprocess.run(args, capture_output=capture_output, text=True, encoding='utf-8', check=check)
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return process.stdout
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def convert_audio_track(stream_index, channels, temp_dir, source_file, should_downmix, bitrate_info):
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"""Extracts, normalizes, and encodes a single audio track to Opus."""
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temp_extracted = temp_dir / f"track_{stream_index}_extracted.flac" # This will be the input for loudnorm pass 1
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temp_normalized = temp_dir / f"track_{stream_index}_normalized.flac"
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final_opus = temp_dir / f"track_{stream_index}_final.opus"
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# Step 1: Extract audio, with conditional downmixing
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print(" - Extracting to FLAC...")
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ffmpeg_args = ["ffmpeg", "-v", "quiet", "-stats", "-y", "-i", str(source_file), "-map", f"0:{stream_index}"]
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final_channels = channels
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if should_downmix and channels >= 6:
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if channels == 6: # 5.1
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print(" (Downmixing 5.1 to Stereo with dialogue boost)")
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ffmpeg_args.extend(["-af", "pan=stereo|c0=c2+0.30*c0+0.30*c4|c1=c2+0.30*c1+0.30*c5"])
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final_channels = 2
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elif channels == 8: # 7.1
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print(" (Downmixing 7.1 to Stereo with dialogue boost)")
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ffmpeg_args.extend(["-af", "pan=stereo|c0=c2+0.30*c0+0.30*c4+0.30*c6|c1=c2+0.30*c1+0.30*c5+0.30*c7"])
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final_channels = 2
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else:
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print(f" ({channels}-channel source, downmixing to stereo using default -ac 2)")
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ffmpeg_args.extend(["-ac", "2"])
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final_channels = 2
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else:
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print(f" (Preserving {channels}-channel layout)")
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ffmpeg_args.extend(["-c:a", "flac", str(temp_extracted)])
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run_cmd(ffmpeg_args)
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# Step 2: Normalize the track with ffmpeg (loudnorm 2-pass)
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print(" - Normalizing Audio Track with ffmpeg (loudnorm 2-pass)...")
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# First pass: Analyze the audio to get loudnorm stats
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# The stats are printed to stderr, so we must use subprocess.run directly to capture it.
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print(" - Pass 1: Analyzing...")
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result = subprocess.run(
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["ffmpeg", "-v", "info", "-i", str(temp_extracted), "-af", "loudnorm=I=-18:LRA=7:tp=-1:print_format=json", "-f", "null", "-"],
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capture_output=True, text=True, check=True)
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# Find the start of the JSON block in stderr and parse it.
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# This is more robust than slicing the last N lines.
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# We find the start and end of the JSON block to avoid parsing extra data.
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stderr_output = result.stderr
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json_start_index = stderr_output.find('{')
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if json_start_index == -1:
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raise ValueError("Could not find start of JSON block in ffmpeg output for loudnorm analysis.")
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brace_level = 0
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json_end_index = -1
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for i, char in enumerate(stderr_output[json_start_index:]):
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if char == '{':
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brace_level += 1
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elif char == '}':
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brace_level -= 1
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if brace_level == 0:
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json_end_index = json_start_index + i + 1
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break
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stats = json.loads(stderr_output[json_start_index:json_end_index])
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# Second pass: Apply the normalization using the stats from the first pass
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print(" - Pass 2: Applying normalization...")
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run_cmd([
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"ffmpeg", "-v", "quiet", "-stats", "-y", "-i", str(temp_extracted), "-af",
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f"loudnorm=I=-18: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']}",
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"-c:a", "flac", str(temp_normalized)
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])
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# Step 3: Encode to Opus with the correct bitrate
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bitrate = "192k" # Fallback
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if final_channels == 1:
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bitrate = "64k"
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elif final_channels == 2:
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bitrate = "128k"
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elif final_channels == 6:
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bitrate = "256k"
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elif final_channels == 8:
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bitrate = "384k"
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print(f" - Encoding to Opus at {bitrate}...")
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print(f" Source: {bitrate_info} -> Destination: Opus {bitrate} ({final_channels} channels)")
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run_cmd(["opusenc", "--vbr", "--bitrate", bitrate, str(temp_normalized), str(final_opus)])
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return final_opus, final_channels, bitrate
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def main():
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"""Main script logic."""
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parser = argparse.ArgumentParser(description="Batch processes MKV file audio tracks to Opus.")
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parser.add_argument("--downmix", action="store_true", help="If present, multi-channel audio will be downmixed to stereo.")
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args = parser.parse_args()
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check_tools()
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# Define directory paths but don't create them yet
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DIR_COMPLETED = Path("completed")
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DIR_ORIGINAL = Path("original")
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DIR_LOGS = Path("conv_logs")
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current_dir = Path(".")
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# Check if there are any MKV files to process
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files_to_process = sorted(
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f for f in current_dir.glob("*.mkv")
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if not f.name.startswith("temp-output-")
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)
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if not files_to_process:
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print("No MKV files found to process. Exiting.")
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return # Exit without creating directories
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# Create directories only when we actually have files to process
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DIR_COMPLETED.mkdir(exist_ok=True)
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DIR_ORIGINAL.mkdir(exist_ok=True)
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DIR_LOGS.mkdir(exist_ok=True)
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for file_path in files_to_process:
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# Setup logging
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log_file_path = DIR_LOGS / f"{file_path.name}.log"
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log_file = open(log_file_path, 'w', encoding='utf-8')
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original_stdout = sys.stdout
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original_stderr = sys.stderr
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sys.stdout = Tee(original_stdout, log_file)
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sys.stderr = Tee(original_stderr, log_file)
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try:
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print("-" * shutil.get_terminal_size(fallback=(80, 24)).columns)
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print(f"Starting processing for: {file_path.name}")
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print(f"Log file: {log_file_path}")
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start_time = datetime.now()
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intermediate_output_file = current_dir / f"temp-output-{file_path.name}"
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temp_dir = Path(tempfile.mkdtemp(prefix="mkvopusenc_"))
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print(f"Temporary directory for audio created at: {temp_dir}")
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# 3. --- Get Media Information ---
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print(f"Analyzing file: {file_path}")
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ffprobe_info_json = run_cmd(["ffprobe", "-v", "quiet", "-print_format", "json", "-show_streams", "-show_format", str(file_path)], capture_output=True)
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ffprobe_info = json.loads(ffprobe_info_json)
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mkvmerge_info_json = run_cmd(["mkvmerge", "-J", str(file_path)], capture_output=True)
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mkv_info = json.loads(mkvmerge_info_json)
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mediainfo_json_str = run_cmd(["mediainfo", "--Output=JSON", "-f", str(file_path)], capture_output=True)
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media_info = json.loads(mediainfo_json_str)
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# 4. --- Prepare for Final mkvmerge Command ---
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processed_audio_files = []
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tids_of_reencoded_tracks = []
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# 5. --- Process Each Audio Stream ---
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audio_streams = [s for s in ffprobe_info.get("streams", []) if s.get("codec_type") == "audio"]
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# Check if the file has any audio streams
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if not audio_streams:
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print(f"Warning: No audio streams found in '{file_path.name}'. Skipping file.")
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continue
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mkv_tracks_list = mkv_info.get("tracks", [])
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mkv_audio_tracks = [t for t in mkv_tracks_list if t.get("type") == "audio"]
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media_tracks_data = media_info.get("media", {}).get("track", [])
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mediainfo_audio_tracks = {int(t.get("StreamOrder", -1)): t for t in media_tracks_data if t.get("@type") == "Audio"}
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print("\n=== Audio Track Analysis ===")
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for audio_stream_idx, stream in enumerate(audio_streams):
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stream_index = stream["index"]
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codec = stream.get("codec_name")
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channels = stream.get("channels", 2)
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language = stream.get("tags", {}).get("language", "und")
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track_id = -1
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mkv_track = {}
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if audio_stream_idx < len(mkv_audio_tracks):
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mkv_track = mkv_audio_tracks[audio_stream_idx]
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track_id = mkv_track.get("id", -1)
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if track_id == -1:
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print(f" -> Warning: Could not map ffprobe audio stream index {stream_index} to an mkvmerge track ID. Skipping this track.")
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continue
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track_title = mkv_track.get("properties", {}).get("track_name", "")
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track_delay = 0
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audio_track_info = mediainfo_audio_tracks.get(stream_index)
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# Get bitrate information from mediainfo
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bitrate = "Unknown"
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if audio_track_info:
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if "BitRate" in audio_track_info:
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try:
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br_value = int(audio_track_info["BitRate"])
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bitrate = f"{int(br_value/1000)}k"
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except (ValueError, TypeError):
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pass
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elif "BitRate_Nominal" in audio_track_info:
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try:
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br_value = int(audio_track_info["BitRate_Nominal"])
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bitrate = f"{int(br_value/1000)}k"
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except (ValueError, TypeError):
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pass
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delay_raw = audio_track_info.get("Video_Delay") if audio_track_info else None
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if delay_raw is not None:
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try:
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delay_val = float(delay_raw)
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# If the value is a float < 1, it's seconds, so convert to ms.
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if delay_val < 1 and delay_val > -1:
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track_delay = int(round(delay_val * 1000))
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else:
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track_delay = int(round(delay_val))
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except Exception:
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track_delay = 0
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track_info = f"Audio Stream #{stream_index} (TID: {track_id}, Codec: {codec}, Bitrate: {bitrate}, Channels: {channels})"
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if track_title:
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track_info += f", Title: '{track_title}'"
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if language != "und":
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track_info += f", Language: {language}"
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if track_delay != 0:
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track_info += f", Delay: {track_delay}ms"
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print(f"\nProcessing {track_info}")
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if codec in {"aac", "opus"}:
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print(f" -> Action: Remuxing track (keeping original {codec.upper()} {bitrate})")
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# This track will be kept from the original file, so we don't need to add it to a special list.
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else:
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bitrate_info = f"{codec.upper()} {bitrate}"
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print(f" -> Action: Re-encoding codec '{codec}' to Opus")
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opus_file, final_channels, final_bitrate = convert_audio_track(
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stream_index, channels, temp_dir, file_path, args.downmix, bitrate_info
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)
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processed_audio_files.append({
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"Path": opus_file,
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"Language": language,
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"Title": track_title,
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"Delay": track_delay
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})
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tids_of_reencoded_tracks.append(str(track_id))
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# 6. --- Construct and Execute Final mkvmerge Command ---
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print("\n=== Final MKV Creation ===")
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print("Assembling final mkvmerge command...")
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mkvmerge_args = ["mkvmerge", "-o", str(intermediate_output_file)]
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# If no audio was re-encoded, we are just doing a full remux of the original file.
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if not processed_audio_files:
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print(" -> All audio tracks are in the desired format. Performing a full remux.")
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mkvmerge_args.append(str(file_path))
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else:
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# If we re-encoded audio, copy everything from the source EXCEPT the original audio tracks that we replaced.
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mkvmerge_args.extend(["--audio-tracks", "!" + ",".join(tids_of_reencoded_tracks)])
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mkvmerge_args.append(str(file_path))
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# Add the newly encoded Opus audio files.
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for file_info in processed_audio_files:
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mkvmerge_args.extend(["--language", f"0:{file_info['Language']}"])
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if file_info['Title']:
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mkvmerge_args.extend(["--track-name", f"0:{file_info['Title']}"])
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if file_info['Delay'] != 0:
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mkvmerge_args.extend(["--sync", f"0:{file_info['Delay']}"])
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mkvmerge_args.append(str(file_info["Path"]))
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print(f"Executing mkvmerge...")
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run_cmd(mkvmerge_args)
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print("MKV creation complete")
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# Move files to their final destinations
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print("\n=== File Management ===")
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print(f"Moving processed file to: {DIR_COMPLETED / file_path.name}")
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shutil.move(str(intermediate_output_file), DIR_COMPLETED / file_path.name)
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print(f"Moving original file to: {DIR_ORIGINAL / file_path.name}")
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shutil.move(str(file_path), DIR_ORIGINAL / file_path.name)
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# Display total runtime
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runtime = datetime.now() - start_time
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runtime_str = str(runtime).split('.')[0] # Remove milliseconds
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print(f"\nTotal processing time: {runtime_str}")
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except Exception as e:
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print(f"\nAn error occurred while processing '{file_path.name}': {e}", file=sys.stderr)
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if intermediate_output_file.exists():
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intermediate_output_file.unlink()
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finally:
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# 7. --- Cleanup ---
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print("\n=== Cleanup ===")
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print("Cleaning up temporary files...")
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if temp_dir.exists():
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shutil.rmtree(temp_dir)
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print("Temporary directory removed.")
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# Restore stdout/stderr and close log file
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sys.stdout = original_stdout
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sys.stderr = original_stderr
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log_file.close()
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if __name__ == "__main__":
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main() |