Check if your AC3 track is (rare) or needs shifting. Use MediaInfo to see audio delay embedded in the container. 2. Tools Needed | Tool | Purpose | |------|---------| | MKVToolNix (GUI) | Remux, set audio delay, add AC3 without re-encoding | | Audacity + FFmpeg | View waveforms, measure offset | | ffmpeg (command line) | Extract/convert/delay AC3 precisely | | Avidemux | Quick preview and A/V sync checking | | PotPlayer / VLC | Play with audio track offset temporarily | 3. Step-by-Step Sync Guide Step 1 – Extract the reference audio from video If your video has any audio (e.g., AAC), extract it to compare with AC3:
This guide assumes you have the video file (e.g., an Amazon/Netflix/Blu-ray rip) and a separate AC3 audio track (e.g., from a different region release, DVD, or 5.1 surround source). | Item | Notes | |------|-------| | Video file | Usually x264/x265, 23.976fps or 24fps, runtime ~21–22 min | | AC3 audio | Could be 2.0 (stereo) or 5.1 (surround), from a different release | | Reference runtime | Official runtime: 21:12 (without credits) / 21:40 (with credits) |
