There are many products on the market for capturing RCA output onto a computer, but they all seem to be either low quality or extremely expensive. When talking to a fellow Youtuber recently, I came to the conclusion that it would be "not easy, but possible" to build a capture device from scratch. Today, I was looking around for a project to work on over the next couple of weeks, and I uttered the words "Well, how hard can it be?". Considering that I'm mainly a web developer, and I have very little experience with hardware, I'm guessing the answer is somewhere between "very" and "almost impossible", but I want to try anyway.
The first step will be to look at the specifications of RCA leads and USB cables. I already know that RCA is analogue and USB is digital, so I'll need a DAC to convert the signal before it's transmitted to the computer. What I don't know is how much data will need to be transferred, whether USB 2.0 will be able to handle it without compression, or what sort of processing power I'll need in order to convert the signal in real-time.
It would possibly be easier to hijack the output of a cheap HDMI splitter cable, rather than converting the analog RCA signal, but one of the uses for this will be to capture audio and video from the Playstation 2 system as well as the Playstation 3. Since the Playstation 2 doesn't have HDMI output, I'm stuck with working with RCA.