WebCam & USB to RCA converters

[RMMK]

I have search the whole market for composite video to usb adapters but couldnt find them. I need them for connecting my web cam to the following circuit for transmitting the video to any television at some distance for the web cam.



The question i wanna ask is whether my approach is correct or not and also since I couldnt find these S-video converters will u plzzzz give me a circuit diagram for the same so that I could build one??? Plzz HelP!!!! Or give me an alternate approach!!

 

[davoud]

way you need Video to usb converter? if you have composite video why you want to convert it to USB ? if you want to say convert USB Web cam to composite I think you need a controller with usb host and related programs for connecting to it . a easy way is change your camera and buy a simple composite camera for this issue.

 

[RMMK]

way you need Video to usb converter? if you have composite video why you want to convert it to USB ? if you want to say convert USB Web cam to composite I think you need a controller with usb host and related programs for connecting to it . a easy way is change your camera and buy a simple composite camera for this issue.

The thing is that its a usb web cam and secondly its very hard to find a composite camera....... I found some cctv ones but the cost real bucks!

 

[davoud]

https://dx.com/p/ntsc-mini-surveillance-av-camera-628x582px-6019

 

[betwixt]

I doubt you will find an adapter. Starting with a composite output is the only economical solution. The reason is that webcams scan rates are not the same as standard TV uses and you also have to communicate both ways to the camera to set it up at all. On a PC, there is dialog between the camera driver software and the webcam to set it's resolution and operating modes, if you don't do that they simply wont work. You would have to find an adapter that suited the specific commands your webcam used, there is no standard.

Brian.

 

[RMMK]

I found an interesting article at eHow (link below)..... will it work?

https://www.ehow.co.uk/how_6611359_connect-webcam-tv.html

But still the usb to rca converter is a problem! Isnt there a way to build it???

 

[betwixt]

Step 2 tells you to use a suitable converter so it doesn't answer the problem.

I'm not saying you can't build one, what I'm saying is that by the time you have built a USB host, written all the driver software for it (almost certainly without specifications to work to) then built a DAC and frame buffer with dual-ported RAM, a synchronizing system and composite video frame generator and a control system to coordinate all of this, it would cost maybe 100x more than buying a cheap security camera. At no place in a web cam is there a composite signal to start from so you can't 'tap' into it, they are not composite cameras with a USB interface, the video is digital throughout.

Brian.

 

[RMMK]

okay thanks so in the end i have to buy a security camera having composite interface........ this way i will be able to use the above transmitter....

 

[FvM]

But still the usb to rca converter is a problem! Isnt there a way to build it?

I'm with the comment in another related web discussion "You can safely forget the concept".

 

[RMMK]

I found an interesting way to convert VGA to composite video in the following link under the heading "VGA to composite video in black and white":-
https://www.geocities.ws/podernixie/htpc/cables-en.html

Will this arrangement work??

 

[FvM]

Will this arrangement work??

I presume yes, but how is this related to the original question?

 

[betwixt]

Those are very old ideas that pre-date webcams. I used them back in the early 1980's for testing IBM's first generation VGA cards.

You CAN use the VGA to composite converter but you need a PC to interface to the webcam and a VGA card set to 640x480 resolution to convert the PC video into monochrome NTSC composite video. In other words you are using the computer to control the webcam and generating the lowest resolution video possible to the monitor then intercepting it through a crude DAC to produce composite video. It's a lot of hardware for a poor quality black & white picture! The video is not true composite standard but fairly close as long as you are in a country that uses 525 line 60Hz TV standards.

You have to understand that the webcam uses USB which is a digital system. The PC sends signals to the webcam and the webcam replies with blocks of digital data, at no point does a video signal ever get transferred, it's just chunks of data read from the CCD/CMOS sensor. All the work to make it visible again is done by computation in the PC and it's video card. Without them it is virtually impossible to reconstruct an image let alone one at composite video standard.

Brian.