[Richard Crowley]

Unless you have an experienced crew and adequate setup time, etc (which it sounds like you do NOT), a boom mic is more useful to a professional sound person.

If you want decent, intelligible pickup of dialog from multiple people (and it sounds like amateurs, not professional actors), I would say that “lav” body-mics are the most likely to get you what you need. If you don’t want the mics to be visible (why?, people know they are looking at a produced video!) then hide them. The art of hiding the mics and avoiding clothes rustle, etc. is not a 10-second process of clipping it on and hoping for the best. If you want quality results, you must plan to work for it. Note also that clip-on lav mics don’t HAVE to be wireless. If the scenes are in a fixed setting, wired mics are a perfectly fine option.

“Plant mics” were popular back when mics were the size of a flashlight. And they had severe limitations because of proximity vs. ambient noise, etc. With modern lav mics the size of a match-head, I can’t think of why “plant mics” would be useful.

Note that the Rode “smartlav” is only a microphone. You need a recorder or smart phone, etc. to plug it into for recording. And then you must offload the recording. And with a standalone recording solution, you can’t monitor what the mic is doing, and you could waste a lot of time only to discover a bad recording from one of the players.

If you are recording 5 or 6 mics, you need to get the Zoom XLR adapter to allow 6 channel recording. With the limited crew you have, you probably don’t want to attempt to MIX the dialog while shooting.

If it were me, I would buy 4 or 6 Oscar Sound Tech OST-801 wired lavs and a bunch of mic cable. https://oscarsoundtech.com/services.html They are excellent value for the price, available in several colors, and very tiny to make them easy to hide. You probably should get some “vampire clips” to attach them to clothing, etc. And some “moleskin” to mitigate rustling noises and/or for attaching to skin, etc.

It doesn’t sound like your scenes involve extensive movement, so I agree that wireless may be more trouble than its worth.

[Richard Crowley]

Your question only raises many more questions.
What mics are you using NOW? Are they YOUR mics? Or are they whatever comes with the venue?
Who is operating the camera?
What do you mean by “the boom mic”?
How do you make the current audio recording for your podcast?
If you are happy with the podcast recording, why wouldn’t you simply feed that into the camera?

As Mr. Reynolds suggested, hiring an audio expert to help you set up everything may be a good investment. But if that isn’t in the budget, then much more complete details are necessary to attempt to to help you here.

[Richard Crowley]

Generally, you get what you pay for. The general consensus is that a decent, reliable wireless kit (mic, transmitter, receiver) will cost >$500 each. The Sennheiser G3 (~$650) is often cited as the lowest-price decent wireless mic kit. There are units that cost up to 5x more than that, just so that you know what the ballpark looks like.

Even a $100 for ONE channel wireless kit is a cheap, fiddly, disposable, flimsy, plastic toy. It is hard to believe that anyone can sell a unit at $100 with FOUR channels that was even occasionally functional. If you have $100 to waste, go for it and report back to us.

[Richard Crowley]

My immediate guess would be that C908 and/or C913 has dried out and is no longer passing low frequencies because of diminished capacitance. Or perhaps even C911.

[Richard Crowley]

Please identify exactly WHICH Shure mixer you are talking about.
Please identify exactly what headphones you are talking about.
Do these headphones sound OK with other gear?

[Richard Crowley]

Your drift is not unusual for gear of that caliber. You get what you pay for.

You can try simply dragging the length of the video to match the audio (or vice-versa). You might get lucky.

A 13-minute long interview with no cuts may be a good candidate for a non-habit-forming sleeping-aid.

[Richard Crowley]

“TC” would appear to refer to timecode which you are not using. So that seems like a red-herring.

7 seconds of drift over 13 minutes is not abnormal for gear as you are using. You can’t expect to have better sync than that for low-end consumer gear which is not gen-locked together. This is a 1.6% error. You are not the first to complain about speed error in prosumer gear.

The difference between 25 FPS and 24 FPS is 4.2% which is enormously greater than what you are seeing. IMHO this proves rather conclusively that this has nothing to do with FPS.

Simply pull up the video to match the audio wherever there is a video edit point. Surely you are not using the entire 13 minute video clip without edits.

[Richard Crowley]

You say “I have audio recorded on an H4N (24 fps)…”
What does that MEAN exaxtly? The only choice you have when recording on H4n, is either 44.1 KHz or 48 KHz. How do you “record at 24 FPS”? What does that MEAN?

So did you record at 44.1 KHz or did you record at 48 KHz? Those are your only two choices. There is no FPS here.

Have you done this before? Did it work before and now it doesn’t?

What does “audio drift around the 1 minute mark” mean? How MUCH is the drift? Is the drift constant as you go through the 13 minutes?

Are you aware that drift over several minutes is normal for low-end pro-sumer gear like the H4n and typical DSLR cameras?

[Richard Crowley]

Audio is not recorded in Frames Per Second (FPS).
Audio is recorded in “samples per second”.
The standard sample rate for video is 48,000 (“48K”) samples per second.
Whether the picture is film or video, and regardless of the frame rate of the picture.

What makes you think the audio doesn’t sync? Have you tried it? If it doesn’t sync, it is not a problem with “frame rate” as that concept does not exist in audio.

[Richard Crowley]

The bit-format of a WAV file is described in, for example, the article in Wikipedia: https://en.wikipedia.org/wiki/WAV

Note that that Wikipedia observes that the WAV/RIFF format is not precisely defined, and there are several semi-legal variations. You could use this variability to your advantage to detect differences between the file in question and your reference file.

Note also that there are forensic “detectives” who specialize in this kind of analysis. If the issue is of sufficient importance (legally, financially, etc.) then you could consider hiring an expert.