Newbie Questions for Automotive Recording

[davemd]

Hi everyone,
I am using Zoom H2N audio recording mic and a GoPro Hero 3 black edition to start off. I have done some searching but am unable to pinpoint some of my questions. So here’s my scenario, I am attempting to do varies videos of car racing / driving / ect. I normally film with my Gopro cam at 1080p 30fps (sometimes 1440k cinema 30fps) and place my H2N under the hood.
Question #1
I would like to build a bracket to thread my mic onto (it has a tripod threaded hole in the bottom) my question is does anyone know size the bolt would be needed? Standard or metric / thread pitch? Also I plan to mount this bracket under my car near the exhaust, should I build the bracket to slightly shield the mic so only the top is exposed, an near the exhaust or should I use something like a deadcat on the end of it to reduce wind noise?
Question #2
I do not know much about the actual recording process technical techniques, but what is the recommended bit rate to record at? Being that this is a lot of engine noises (turbo spool, exhaust notes ect) does that differ in the rate that I should record at? I have done several videos using 2116kps and it seems to sound ok and I am able to use the gain properly to hear what I want, but when I attempt to sync it to my video no matter how close I get it, it seems to play back faster than my video plays (never matches up even when I know its within half a second from the video, using the clap method)?
Question #3
I am about to get the Gopro mic-in adapter to hopefully get the sync dead on, but have no idea if the h2n can record directly into the camera? An does the settings have to be in any special mode?

Thank you for any input you have

 

[Seidy]

1) The tripod mount hole should be size 1/4". You can find the right size on ebay:
1 4 tripod screw | eBay

If you are planning to put the zoom under the car you should cover it to protect it against dirt, small rocks and such. Putting the Zoom into non-lubricated condom seems to be an option. (see the pop-filter thread for example: https://homerecording.com/bbs/general-discussions/newbies/pop-filters-356749/6/#post4044141)

2) If I were you I'd record at 48khz/24bit. That should sync up with your video properly. (Maybe you were recording at 44khz so it didn't sync up)
And of course record at low levels - the loudest it should read on meters would be around -12db.

3) I see that the H2n has Line out so you can take the signal and run it to Gopro. However if the Gopro has only mic in then it means you have to turn to output volume down a lot on Zoom. This is because Line level signals are a lot stronger than mic level and thus you could clip your gopro input. And that will sound nasty. Another thing - is the mic input also for stereo signals?

 

[mjbphotos]

I'm not sure why you want to record another audio track besides what the camera picks up. The sound in the cockpit - assuming that's where you have the camera mounted will give a better 'you are there' sound than from an externally-mounted mic. Of course if this is for an open-wheeled car and the camera is mounted on the roll bar (getting the wind noise), that's a different thing.
If you insist on recording with anotehr mic, make sure it isn't picking up wind noise.
BTW, I'm a long-time sports car fan, been to hundreds of races and watched tons of in-car videos over the years, and don't ever recall watching one where anyone used a mic mounted elsewhere (I can't remember any open-wheel cars where the in-car audio was really used much, it always tended to be 'windy' in old videos). The sound of the exhaust, if you use a microphone near it, will be quite loud, you will have to have the recorder's gain turned way down, and make sure you don't have the mic cable too close to the exhaust - it'll melt the insulation!

 

[davemd]

Thanks guys, the main reason I want to use an external mic is for a couple of reasons. First reason is I Mount the camera outside the car ( so lots of wind). For interior mounted shots it doesn't capture the greatest audio either due to its completely sealed case that it is in (until gopro releases a skeleton case for hero 3). I'll post a link to my video so you can see.
Thanks alot