It cuts the video correctly but the audio is not correct

cut_to_length.py

@@ -0,0 +1,128 @@
+#!/usr/bin/env python3
+
+import subprocess
+import json
+import sys
+import shutil
+from pathlib import Path
+
+def run(cmd):
+    return subprocess.run(cmd, capture_output=True, text=True, check=True)
+
+
+def probe_video(path):
+    cmd = [
+        "ffprobe",
+        "-v", "error",
+        "-print_format", "json",
+        "-show_streams",
+        "-show_format",
+        path
+    ]
+
+    data = json.loads(run(cmd).stdout)
+
+    duration = float(data["format"]["duration"])
+
+    for s in data["streams"]:
+        if s["codec_type"] == "video":
+            num, den = s["r_frame_rate"].split("/")
+            fps = float(num) / float(den)
+            codec = s["codec_name"]
+            start_time = float(s.get("start_time", 0))
+            return fps, duration, codec, start_time
+
+    raise RuntimeError("No video stream found")
+
+def vaapi_cut(inp, outp, start, end, codec="h264_vaapi"):
+    encoder = codec
+
+    cmd = [
+        "ffmpeg",
+        "-y",
+        "-vaapi_device", "/dev/dri/renderD128",
+
+        "-ss", str(start),
+        "-to", str(end),
+
+        "-i", inp,
+        "-map", "0",
+
+        "-vf", "format=nv12,hwupload",
+
+        "-c:v", encoder,
+        "-qp", "20",
+
+        "-c:a", "copy",
+        "-c:s", "copy",
+        "-c:d", "copy",
+        "-c:t", "copy",
+
+        outp
+    ]
+
+    subprocess.run(cmd, check=True)
+
+def extract_audio(output_mkv, out_audio):
+    # Extract the first (and only) audio track
+    run([
+        "mkvextract",
+        "tracks",
+        output_mkv,
+        f"1:{out_audio}"  # track IDs are usually 0 for video, 1 for audio
+    ])
+
+def mux_audio_into_copy(inp2, audio_file, output_dir):
+    output_dir = Path(output_dir)
+    output_dir.mkdir(exist_ok=True)
+
+    copied_video = output_dir / Path(inp2).name
+    shutil.copy2(inp2, copied_video)
+
+    final_output = output_dir / "final_with_audio.mkv"
+
+    run([
+        "mkvmerge",
+        "-o", str(final_output),
+        str(copied_video),
+        "--language", "0:deu",  # assign German language
+        str(audio_file)
+    ])
+
+    return final_output
+
+def main():
+    inp = f"/home/honney/projects/mkv/AnoHana The Flower We Saw That Day (2011-2011) [imdbid-tt1913273]/Season 01/AnoHana The Flower We Saw That Day S01E001.mkv"
+    inp2 = f"/home/honney/projects/mkv/Anohana - The Flower We Saw That Day - S01 (BD 1080p HEVC Opus) [derpie]/[derpie] Anohana - The Flower We Saw That Day - S01E01 (BD 1080p HEVC Opus) [Dual Audio].mkv"
+    
+    
+    outp = "./output.mkv"
+    n1 = 24
+
+    fps, _, _, vstart = probe_video(inp)
+    _, duration, _, _ = probe_video(inp2)
+
+    start = vstart + (n1 / fps)
+    end = duration + start
+
+    if end <= start:
+        raise ValueError("n2 must be greater than n1")
+
+    print(f"fps: {fps}")
+    print(f"cutting from frame {n1} to {end*fps}")
+    print(f"time range: {start:.6f}s -> {end:.6f}s")
+
+    print("Trying stream copy...")
+    vaapi_cut(inp, outp, start, end)
+
+    output_dir = "./output_dir"
+    audio_file = Path(output_dir) / "german_audio.aac"
+
+    extract_audio(outp, audio_file)
+    
+    final_file = mux_audio_into_copy(inp2, audio_file, output_dir)
+
+    print(f"Final file created at: {final_file}")
+
+if __name__ == "__main__":
+    main()