View Full Version : Forcing the levels (audio)
03-24-2009, 03:22 PM
Has any one got any where with forcing a consistent level with the audio ?
(Im looking forward to the beachtek !)
I saw an idea for using an ipod
I would be happy to lose a channel
Or could a high frequency be used and then filtered
I have an Ipod at my disposal and am using the rode vid mic (I also have a sanken condenser mic that requires power)
Im looking to do really basic chats near the camera for the moment
Do any of the current beachtek solutions (or others work)
Im not keen on synching a seperate sound track if possible
03-24-2009, 08:28 PM
Based upon what I have heard and know about the 5D MKII, you will never obtain more than mediocre sound with it no matter what you do. Auto levels mess everything up. I am using Zoom H4N as soon as they ship. Much better quality and double system sound ain't as hard as you think it is, it just means you have to be organized and not sloppy. Slate every take and keep a sound report.
03-24-2009, 10:35 PM
"Auto levels mess everything up " - that is the point of broadcasting a fixed tone into one channel or a filterable high freqency to both - to force the auto levels to be fixed
The simple concept being to have track on your ipod - a fixed tone
pipe that track into one channel - the mic into the other channel
do testing and use the ipods volume control to 'force' a fixed level (louder IPOD = less 'gain')
the more complex concept is to mix your mic and a filterable high frequency Ipod ' tune' in both channels and then use an audio filter to cut the tone from the audio
I will try some seperate recorder tests too - Ill use the EX1 :)
03-25-2009, 04:54 AM
If the auto gain takes place in an analogue circuit before it gets A-D converted, it may be possible to pump in a much higher frequency way above the human range of hearing and the sampling - which would hold the gain at a fixed level?
Build a simple circuit to generate 150kHz, feed it to the camera with the audio and see what happens? :)
03-25-2009, 06:12 AM
Indeed - thats the theory - any one got it working !
03-25-2009, 08:33 AM
There is this thing you are forgetting about called crosstalk and channel separation. Crappy audio circuits generally have really lousy crosstalk and separation specs. Feel free to try it but I still think you are trying to fit a square peg into a round hole. This is like the days of the Sony VX2000/2100 and the PD150/170 DV camcorders. Everyone loved Sony, all anyone could talk about was how great these Sony DV camcorders where when in fact they were the worst sounding, lowest audio quality camcorders ever created. People went as far as sending their cameras to the U.K. to pay hundreds of dollars to have the audio circuit ripped out and modified to bypass the horrendously bad Sony circuitry. Class action lawsuits were filed against Sony for selling a so called pro camcorder line with unusable audio.
The bottom line is, Canon is a still photo company that happens to make some camcorders that are decent. Then their still guys, without consulting with or communicating with the video division, decided to make a still camera that shoots video. Of course, the audio is going to suck, they are still camera engineers and they think, "give the users auto everything". No matter what you do, the audio quality is going to be really lousy. Double system sound is the way to go if you care about sound.
03-25-2009, 08:45 AM
Im not forgetting about anything - or even saying it will work - Im enquiring on a forum for the experience of others !
If the 'high frequency' method works and there is a suitable audio filter in post then crosstalk is not an issue
For the 'single channel' solution crosstalk could indeed cause the idea (not mine BTW) to be a non runner
I beleive this method is what will be the core of the future beachtek BTW
In terms of acheivable quality I beleive there are various benchmarks
My goal simple talking heads in run n gun situations where the sound is not ruined by wind noise or the background ambience 'whooshing up' during pauses in the chat - In a quiet room the 5d sound is 'ok' - do you have one ?
Of course were one attempting to record drama, concerts or other specialised or high budget situations a seperate solution would be a requirement - Ideally with a soundman, a Red Camera and a truck full of grip
Im looking to optimise the tool that I own..
03-25-2009, 09:02 AM
This cat did http://www.vimeo.com/3072099
03-29-2009, 11:15 PM
Is there any boxes like a Beachtek, that are suitable on use with Canon? Or is some sort of double system is the way to go?
03-29-2009, 11:31 PM
beachtek are developing one
I dont know about similar - links please
Dual is the best for 'quality' - but Im after 'adequate' with a simple workflow..