#1371 - effendi - Fri Jan 17, 2003 8:08 am
hey all...
would anybody know anything about how the output of a USB webcam is structured. I am looking to capture the image from the webcam and send wirelessly to the GBA ... Before i do so i figure i should have a basic understanding of the serial output... any info or links to info would be greatly appreciated..... thank you
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#1373 - ampz - Fri Jan 17, 2003 9:32 am
USB is not simply a "serial output" of the image.
USB is waaay too complicated, you can't do this.
If you want a cam, buy one with a general interface.
For wireless transmission of a image you need serious bandwidths, not sure how you'll be able to do that.
#1559 - effendi - Mon Jan 20, 2003 4:11 am
what we are thinking now is we have a camera with analog output ... we are thinking of breaking up the RGB values from the signal and giving them a 12 bit code ..... we will be cutting the number of possible colours to around 4000. and also our framerate will be very low....
thanx for your input
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#1561 - tepples - Mon Jan 20, 2003 4:39 am
| effendi wrote: |
| what we are thinking now is we have a camera with analog output |
This would in effect put video digitizer hardware on a cartridge.
| Quote: |
| we are thinking of breaking up the RGB values from the signal and giving them a 12 bit code |
You can go full 15 bit on this as long as you do the gamma correction inside the cartridge hardware.
| Quote: |
| and also our framerate will be very low |
There are 280,896 cycles per frame. A DMA from the cartridge to VRAM can pull 16 bits per 2 cycles. A 240x160 mode 3 (15-bit) bitmap takes 38,400 16-bit words, which should take 76,800 cycles to transfer from the cartridge. It should fit comfortably within a frame's time.
By now, it looks a lot like a TV tuner. You might as well broadcast the video camera's output on a weak TV signal and then pick it up on a TV tuner like the one available from Lik Sang.
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