Hi John, the method I use to sync the video (in my case iPad) to audio (either direct or via mic into Focusrite) is to visibly strike a single chord and sync the audio with the visible strike action.
The alternative to that is to align the proper audio track with the audio (which won’t be used and later muted) which is recorded via the iPad.
The spike in both audio tracks can be clearly seen in the DAW and easily aligned from the single chord strike. It acts just like the ‘clapper board’ in the film industry.
I think Bryce first mentioned this technique some years ago.

Richard

Exactly.
Ever wondered why there is that “clap” before every movie scene?

I also recommend removing the native video audio track after you have imported and aligned the external audio file.

First I add my iPhone video (with it’s audio) to my video editor, then I add the audio track from my DAW below it. I can see both audio tracks, but sometimes I increase the vertical scale so the volume peaks show up better. Sometimes I add a clap or a count-in to make it easier to sync the two audio tracks, but usually I don’t need to, because their will be one or more taller peaks that stand out and I can just line those up. You get good at it after a while. Once they are lined up, I mute the audio on the iPhone track (all video editors can do this), so there is only the DAW audio track that will be heard. The iPhone audio is greatly inferior to the DAW audio, so why pollute your audio by leaving it in the final product? And also, if you do it this way, the only reason to sync the two audio tracks precisely is so that your fingers will be matching the sound. Even if they are not 100% precisely synced, no one will notice.

Yep, what they all said. I will add, the more you do it the easier it gets.

If you happen to be using GarageBand, it has a very handy feature where you can add a video as a track to the GB project. Then line up the waveforms of the video and the higher quality audio as others have mentioned above, matching up a sharp reference peak. Once they are lined up, you can mute the video track and then there is an option to write the audio from the project back to the video. At that point, you have just the high quality audio all synced up on your video file.

I always sync up the audio tracks in the video editor, which in my case is Adobe Premiere.

Richard