The digital camera node interfaces with standard USB cameras (e.g. the Logitech Quickcam) using OpenCV and publishes image data using the image_transport model, which can automatically generate compressed message types. That is, the theora streaming video compression is only enabled when the image is actually requested compressed, e.g. by calling

• /image_view image:=/image_raw theora

Notice that you have to compile theora separately, i.e. using

• rosmake theora_image_transport

• rosmake compressed_image_transport