A standard video source, such as a

A standard video source, such as a camcorder, VCR, or laserdisk player, transmits the analog video signal to the video-capture board, while analog audio is sent to a sound board inside the PC. The capture board utilizes analog-to-digital converters (ADCs) to transform the analog video signal into binary code. The video footage can be captured as a raw sequence of video frames, which is sent to and held in system RAM where software compression is performed. Meanwhile, the audio signal undergoes analog-to-digital conversion by the sound board's converters. This information is also sent to the PC's main system RAM. After the video and sound tracks have been captured, the captured signal can be stored directly to the hard disk or software-based compression can be applied. Generally, the digital video and audio signals are stored as a synchronized, or interleaved. AVI file on the hard disk. Because the video-capture boards in this roundup do not provide hardware-base decompression support, the CPU was responsible for decompressing the files in system memory. The decompressed digital video portion of the AVI file is sent from memory to a conventional VGA or SVGA graphics adapter, where it is converted into a non-interlaced analog signal.