Hauppauge WinTV USB - Manual (Page 43)

How WinTV-USB Works
Your WinTV-USB contains a 125 channel cable ready TV tuner, a video digitizer,
a video compression engine and a USB bus controller. WinTV-USB displays
video and audio in the following way:
Under software control, the WinTV-USB either tunes to a TV channel or selects
the external audio/video input source. The audio from the chosen source is
passed to the LineOut jack on the WinTV-USB, while the video from the selected
source is digitized and compressed. The compressed video is sent over the
USB cable into your PC.
Once the compressed video is in your PC, the WinTV-USB software driver
decompresses the video and sends a reconstituted frame to your graphics dis-
play adapter 30 times each second (25 times per second in Europe and other
PAL areas).
Your graphics display adapter then resizes the video image to fill the window
size that you have chosen for the WinTV window.
Typically, you will use the supplied audio cable to carry the audio signal from
the LineOut jack on the WinTV-USB to the LineIn jack on your sound subsys-
tem. Your sound subsystem will then mix this signal with other audio sources
before driving your speakers.
Since the decompression of video images is done by software, a processor with
MMX is required. The actual rate at which the frames are decompressed
depends on the clock speed of your processor, and on whether it is doing any
other "big" jobs, such as rendering complex web pages.
6-1