From PCMAG Review:
The single mini-plug is for both audio output and composite video input using the supplied cable with RCA phono connectors for video and stereo audio. Unfortunately, having one connector for both functions can be a problem. As with most pico projectors, the built-in audio offers far too little volume to be useful, so you'll usually want to use a headset or external sound system. With an external source already plugged into the AV jack, however, there's no place left to plug in, which means you'll have to bypass the projector's AV input and connect the sound system directly to the source.
Brightness and Image Quality
I tested the CP45 with a FIOS set-top box and a Blu-ray player as well as with videos I took with its built-in camcorder and with photos from its 5-megapixel still camera. The 20-lumen rating translates to being bright enough to watch a 40-inch-wide image comfortably for only a short time, even in theater-dark lighting. If you want to watch a full-length movie, you'll probably want to stay with a smaller image.
Image quality earns the same broad brush description as with virtually every other pico projector, which is to say that it's good enough to be usable, but well short of impressive. One potentially annoying distraction was a flickering white line I saw at the top of the screen whenever I used an external source. The line didn't show in any of the video I took with CP45 itself however.
I also saw what looked like unusually obvious judder (the jerky movement that shows in filmed scenes because of the industry standard 24 frames per second for film) as well as a particularly obvious rainbow effect (the tendency for light areas to break up into little red-green-blue rainbows when an object moves on screen). The rainbow artifacts are obvious enough with the CP45 so that anyone who's sensitive to the effect will probably find it annoying.
On the plus side, the projector handles skin tones well and does a reasonably good job with shadow detail (details based on shading). It also does relatively better with photos than video, since the jumpiness and rainbow effect related to movement don't come into play.
Along with the maximum 720p resolution, an important limitation for the camcorder side of the CP45 is the frame rate, at only 30 frames per second (fps) rather than the 60 fps you'd expect in an HD camcorder. Also, as with the 3M CP40, image stabilization was an issue, with the camera producing a jumpy image even when I held it still. The combination translates to video that I found acceptable when projecting with the CP45, but annoying to watch when I moved the MP4 format clips to a computer and used QuickTime to watch them.
Probably the best way to set your expectations for the camcorder side of the CP45 is to think of it as a camera phone without the phone. It can take usable photos and video, and it's small and light enough to carry with you all the time, but it's no match for a full-fledged camcorder.
As a projector, on the other hand, it offers usable, if flawed, image quality, the ability to show video from memory so you don't need to carry a separate video source, and it works as a camcorder too. It also earns extra points for synergy—combining features that enhance each other—which, ultimately, is what makes it worth considering. It's not hard to find better camcorders and better projectors. But by letting you take video or photos and then project them from the same device, the 3M Camcorder Projector CP45 adds a level of convenience—and fun—that you can't get from carrying around two separate products.