I’m completely new to Arduino, and would like to enter this new world.
As a way to learn, and to make something useful for me, I was thinking doing the following project.
To measure the sync of projected image and sound of a video. Is the image right in time with the sound or not? (depending on the video player not being able to play in sync, and to compensate any display delay of either image and sound).
Note: I know this kind of device already exist…
First, a test video needs to be projected. This test video will display both image and sound signal enabling a sync measure. The principle is the simple Bip test: a one white frame is displayed while a bip tone is played, rest of the time dark and silence.
So I need: a microphne that capture the bip sound (that is easy)
A phototransistor (I only need an On/off information, but I need a very fast response, so no LDR it seems) that capture the white frame flashing.
So I guess I could do a Arduino only device, with a display panel for displaying the sync offset in ms, but for a first try I’d like to keep it more simple, and just send audio signals to Max/MSP that will actually do the measurments (it also interrest me to see how Arduino can generate output sounds…). Then if all works and doesn’t seems too complicated, I’ll try the Arduino only route.
So for now, what I basically need is to control a burst of sound (1kHz sine for instance) when the phototransistor receives some light (the white frame). So I guess I might need a way to set a dark threshold and a White threshold for commuting…
Now, a few questions:
What is the best solution for a battery operated Arduino? Would a single 9V battery be enough? or would it be too much voltage dissipated in the 5V regulator? and not enough capacity? What are your tips about it?
Why are LDR so often mentionned and easy to find in Arduino “stores” and phototransistors (visible light, not IR on top of that) almost never mentionned in Arduino projects? is there something I overlooked on the subject?
As previously stated, I guess it would be doable to controll the gain of an oscillator (done by the Arduino chip) via the phototransistor response? Any difficuties there?
Would the response time be fast (at least just below the ms, as I would like to measure down to the ms). Any tricks for fast acurate response, or designs to avoid?
Now moving to a slightly different path: supposing I do not want anymore to send audio signals to Max/MSP, but instead to send signals via USB. Is it possible? Would I still achieve the ms accuracy? Can Arduino be powered by the USB bus of a computer? (supposing the USB bus to be normal, not underpowered itself)
Thanks for your comments!