best way to sync audio to video?

[justinrh 274]

I record shows from local TV stations, and one of stations always has audio out-of-sync with the video (delayed just enough to be annoying).  I normally convert the recordings to HEVC.  What are some ways to get the audio synced up before conversion?

[visproduction 360]

Just,
I'm not sure if a command in Emby is possible.  You can do it with a ffmpeg command line and therefore have a batch file or Linux script that syncs the audio and creates a new file.

see: https://duckduckgo.com/?q=ffmpeg+change+audio+sync&ia=web

AVIDemux has a + - ms command in audio that does it with a remux.  Both of these are quick, perhaps 15 seconds per 1 hour media.

For 24 fps content every 42 ms is a frame.  The likelyhood that the audio is out of sync is probably on one of those marks.  It's usually one of the first 10 or so.  It's easier to find the best sync by jumping by these numbers. In between is a partial frame and doesn't help. 
   42, 84, 126, 168, 210, 252, 294, 336, 378, 420, 462, 504, ( 1/2 second) 546, 588, 630, 672, 714, 756, 798, 840, 882,  924, 966, 1008 (1000) (1 second)

Maybe someone knows of another way inside Emby to adjust for this.  I don't think it's available yet.

[justinrh 274]

In all the years I've been using avidemux, I hadn't noticed the audio shift UI - thanks!  I give that a try.

Yeah, I didn't expect an Emby fix, so was expecting outside of Emby.  I don't see any way to do this in Handbrake ..

[visproduction 360]

I like AVIDemux.  Any tweak in audio sync plays immediately when you click play inside AVIDemux. If you choose the Play with filters from the top pull down menu, the player remembers where you started.  You can adjust again and click play with filters and you don't have to rewind.  Flip to - if audio comes after video.

[tedfroop21 94]

MKVToolnix will adjust audio sync on recorded files.  I use an app called Shutter Encoder to change file containers for anything that will fit in an MKV container in seconds, then flip it back to MP4 the same way if I want to.   Handbrake will honor those changes if you convert the file.