Frame grabber

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A Datapath VisionRGB-E2s Dual Port Capture Card.
A Datapath VisionHD4 Quad Port Capture Card.

A frame grabber is an electronic device that captures individual, digital still frames from an analog video signal or a digital video stream. It is usually employed as a component of a computer vision system, in which video frames are captured in digital form and then displayed, stored or transmitted in raw or compressed digital form. Historically, frame grabbers were the predominant way to interface cameras to PC's. This has substantially changed in recent years as direct camera connections via USB, Ethernet and IEEE 1394 ("FireWire") interfaces have become prevalent.

Early frame grabbers had only enough memory to acquire (i.e., "grab") and store a single digitized video frame, hence the name. Modern frame grabbers typically can store multiple frames and compress them in real time using algorithms such as MPEG2 and JPEG. Frame grabbers that perform compression on the video frames are referred to as "Active Frame Grabbers," while frame grabbers that simply capture raw video data are called "Passive Frame Grabbers." Technological demands in fields such as radar acquisition, manufacturing and remote guidance have led to the development of frame grabbers with the ability to capture images at high frame rates and resolutions. In addition to video, associated audio can be captured at the same time if the hardware device is so equipped. Some cards have multiple inputs of the same or different signal type that can capture concurrently.


Analog frame grabbers, which accept and process analog video signals, include these circuits:

  • An input signal conditioner to buffer the analog video input signal and protect downstream circuitry.
  • A circuit to recover the horizontal and vertical synchronization pulses from the input signal.
  • An analog-to-digital converter.
  • An NTSC/SECAM/PAL decoder, a function that can also be implemented in software.

Digital frame grabbers, which accept and process digital video streams, include these circuits:

Circuitry common to both analog and digital frame grabbers:

  • Memory for storing the acquired image (i.e., a frame buffer).
  • A bus interface through which a processor can control the acquisition and access the data.
  • General purpose I/O for triggering image acquisition or controlling external equipment.






Network Security[edit]


Personal Use[edit]


Astronomy & Astrophotography[edit]

Amateur astronomers and astrophotographers use frame grabbers when using analog "low light" cameras for live image display and internet video broadcasting of celestial objects. Frame grabbers are essential to connect the analog cameras used in this application to the computers that store or process the images. Day/night security cameras are popular in this field.

See also[edit]