In -car video cameras

[Neil Choi]

Good on you.

Now a quick word of advice, depending where you place the camera, ie on cage in the middle between seats with lots of inside of cabin ie filling 2/3 of viewfinder, you will get over exposure of the outside track scene, which means you will need to set the exposure to say -1.0EV, this generally works fine.  If you don't, you will get fantastic exposure of the inside cabin and a useless washout of the track in front.

But if your camera captures only the outside (ie placed at the A-pillar) then auto exposure is fine.  It is when you have inside and outside to deal with at the same time which causes the exposure discrepancy.

[MD]

HELP !! 

Here is a bit of an update on developments with this camera set up.
Makes great video and audio in general use so you would say , what's your problem?

Well, essentially it is the audio side of things that are actually in two categories.
1 Overload distortion from excessively loud input sound levels in the cabin*.
2 The unit audio sampling rate is 48000kHz but all my playback software uses 44100kHz.

This causes an out of synchronisation of sound with the video.

I have two problems as a consequence that arise:-
1 I cannot reset the audio sampling rate in the recorder.
2 I don't know how to change audio sampling rate in the video players (or if it is possible).

I need some help with this stuff. Perhaps there are a sampling rate converters out there that I have not yet found. Do you know of any? Alternatively are there players out there that can use 48000kHz sampling rates?

Some basic specs. of the recorder:-
Recording format: MOV
Codec:H.264
Best resolution : 1920x1080 (25fps)

* For the overload distortion problem, I intend to experiment with low sensitivity dynamic microphones and if that doesn't do the job, I intend to make an acoustic enclosure that encapsulates the micorphone with perhaps a mechanical calibrating vane that I can adjust to vary the exposure of the mic. to the cabin sound. This is a lot of stuffing around but you know me...I don't just give up at the first sign of a flea fart..

Calling all video Geeks.  We need a resolution here. 

[MD]

Got some more help questions from anyone uploading HD quality video to You Tube. Given the time and data restrictions you have to comply with, what format are you guys uploading with to get a good crisp image ?

I have made a couple of attempts only to wind up with crap that I then had to delete.

[Evan Bottcher]

2 The unit audio sampling rate is 48000kHz but all my playback software uses 44100kHz.

This causes an out of synchronisation of sound with the video.

That's very odd - I've never seen any audio sync problems with interleave formats like MOV.  You shouldn't have to set any audio sampling rate, the player should work it out from the envelope?  Suggest try playback in VLC (http://www.videolan.org/vlc/index.html) as it will usually play ANYTHING.

There's a FAQ on video encoding for youtube here: http://support.google.com/youtube/bin/static.py?hl=en&guide=1728585&page=guide.cs

in particular there's advanced encoding specifications here: http://support.google.com/youtube/bin/static.py?hl=en&topic=1728573&guide=1728585&page=guide.cs

I always upload using H.264 encoded MOV at 1080p or 720p size with whatever default audio settings the video editing software I use (Pinnacle Studio on windows mostly) offers as default.  Seems to work okay.

Once you've uploaded a few videos (and probably they get watched by a few folk), youtube takes away their length restrictions.

[Neil Choi]

MD

WRT the noise distortion or overload, you might have tried this already, you might try covering up the microphone on the unit with various layers of tape, paper or cardboard.  Worth a try as it cost nothing.

Neil

[MD]

Evan & Neil,

Thanks very much for your advices. I have followed through with all the suggestions so far and spent probably the last couple of days just getting acquainted with all the contemporary terminologies and technical issues surrounding all this guff. I think I have absorbed about 3% which could be just enough to blunder through.

In reality my problems start once I try to edit the fresh footage (an analogue term for length of film used to produce the scenes  ). The editor I use is Cyberlink Power Director V7.0. This sucker is as cranky as an unpaid builder's labourer and only fractionally less prone to seizures than Windows Movie Maker. Six out of ten times it will not synchronise the audio with the video and so I get gear changes audio a week later than it actually happened. At other times it gets the two holding hands no problem -now isn't that just like your girlfriend? 

This got me thinking that it it could be the audio sampling rate issue but I tried down sampling from 48khz to 44.1kHz but the girlfriend left town..it didn't work.

I also tried Windows Movie Maker but it doesn't handle MOV files and I am reluctant to do file conversions to keep the quality as high as possible so that program I cannot use.

There is some light at the end of the tunnel because You Tube does accept MOV files and it prefers 48kHz audio codec.

As for the overload distortion Neil, I have tried some of those techniques and they do work to an extent in reducing input levels but they also degrade the nature of the sound and so a nice crisp engine can sound like your old Victa two stroke.

..as for the girlfriend, I am taking her out to lunch.

[MD]

Finally, here is something to show for my effort.
The sound is still crap of course..

http://www.youtube.com/watch?v=a9AKvNVM94A&feature=plcp

[MD]

Well, let's round off this item. As promised, here are some photos of my actual equipment set up with endorsement on the photos themselves explaining what I anticipate you may like to know.

I suppose CAMS would have some safety provisions regarding restraints, even though I do not have to comply as I run under AASA, I have ensured as far as practicality will allow, a secure fastening of all elements consistent with function.

Note that a simple bolting of the dynamic microphone to the roll cage would create a huge distortion from vibrations. It therefore requires a total isolation fixing which in this case is achieved by layers of builders expansion foam positioned above and below the fixing point and at no time does the fixing bolt holding the microphone make contact with the roll cage.

(as a foot note.) Dynamic microphones work on the basis of air moving a magnet that induces a voltage in response to that movement. If a vibration causes that movement, an electrical noise is generated that affects the actual sound it is supposed to replicate. Hence the need for isolation.

[Duk]

That's pretty darn kewl, MD!
I want a similar set up fro my road car, but will mount the camera next too or under the front number plate and use an in car microphone.
Idea being to get some nice footage of my favorite roads but keep the wind noise out of the microphone.

[MD]

Obviously you will need to take care of water penetration,dust and dirt issues if locating the camera so low.

As for the microphone, don't use a dynamic as it will be too insensitive I suspect and a cheap mike from a low budget headset even will do. If you wind up using the same recorder, you wont need any as there is an adequate one incorporated in it and I assume you will place it in the cabin so it will do both jobs. Given the noise in a road car is so great, it should work fine.