Camera board vs. USB camera

[vzaliva]

I am wondering if there are any benefits of using RasperyPI camera board vs. external USB camera
I am mostly interested in performance benefits in terms of CPU and I/O system load. I am considering real-time
computer vision application and it looks like the CPU performance is going to be the bottleneck at Raspberry PI.

Vadim

[jamesh]

The Rapsi camera connects directly to the GPU, and is capable of 1080p30 video encode, 5MP stills in pretty decent quality. Because its attached to the GPU, there is only a little impact on the CPU, leaving it available for other processing.

Webcams (unless they have built in encoding - expensive) are unlikely to get the same performance, and they also use a LOT more CPU.

[vzaliva]

James,

Thanks for the reply. If I am reading non-compressed video frames from the camera, I guess there is not much encoding is happening, so the difference between Webcam and camera board will be not very significant?

[redhawk]

The difference between the Pi Camera and USB webcam is performance and higher frame rate with h.264 video encoding.
With a USB webcam you have low frame rate and no GPU encoding but that doesn't really matter if all you want to do is take photos.

Richard S.

[jamesh]

Moving data over the USB to the CPU takes a fair bit of CPU, with the Pi camera, you don't have that overhead so you have more CPU available.

Picture quality is usually better than webcams, depending on the price you pay.

[vzaliva]

Moving data over the USB to the CPU takes a fair bit of CPU, with the Pi camera, you don't have that overhead so you have more CPU available.

I am curious to see some measurements. If the difference is significant, it could be a good selling point for PI camera unit!

Picture quality is usually better than webcams, depending on the price you pay.

Not necessarily. For example I have Logitech HD Pro Webcam C920 which is a pretty decent camera.

[jamesh]

Moving data over the USB to the CPU takes a fair bit of CPU, with the Pi camera, you don't have that overhead so you have more CPU available.

I am curious to see some measurements. If the difference is significant, it could be a good selling point for PI camera unit!

Picture quality is usually better than webcams, depending on the price you pay.

Not necessarily. For example I have Logitech HD Pro Webcam C920 which is a pretty decent camera.

Er, the high performance and picture quality (and price) of the Raspi camera IS the selling point. Along with size. The difference in performance over a webcam is HUGE. Webcams simply are not as fast. Yes, there are some webcams with high quality, but they are more expensive.

[abshafique]

How about the v4l2 drivers used for the camera board? Do they perform with the same speed in the gpu leaving the cpu free? I am also considering real time image processing applications.

Thanks

[6by9]

How about the v4l2 drivers used for the camera board? Do they perform with the same speed in the gpu leaving the cpu free? I am also considering real time image processing applications.

Yes. The V4L2 drivers use the same GPU acceleration as the raspicam demo apps.