How to sync CD Audio to original audio, Sound Forge
I use Xilisoft to extract the audio from a video file first, because SF very rarely but can cause artifacts if opened directly. This method is extremely useful if you capture video with a normal camera and want to replace the audio with DAW audio. You can then encode the audio to AC3 or other codec, and multiplex (join) to original video using Yamb for .mp4, tsMuxer for .ts or .m2ts, or MXVToolNix for .mkv. Feel free to ask any questions and enjoy.
AC3 enocder: https://www.videohelp.com/software/EncWAVtoAC3
MKVTooNix: https://mkvtoolnix.download/downloads.html or for Windows installers directly: https://www.fosshub.com/MKVToolNix.html