klinky wrote:In terms of video editing, the video card doesn't play a big role in actually processing video. The CPU is the main thing used when it comes to video editing. The CPU has to read the video data, decode it and then send it out to the video card so it can then transfer it to your monitor.
Actually, it depends on what output method you're using, and therefore the video card can play a role in video speed.
CPU speed plays a large part in decoding, yes. But when it comes to displaying that data on-screen, several options exist. Some video players (and video editors) give you the option of rendering video frames as OpenGL textures and rendering them on a plane, and then viewing that plane with an orthogonal camera. For example, both
Xine and
mplayer offer that option. (Not sure about anything on Windows.) In this case, video hardware speed is a factor.
If you have a really slow video card, then any video output system that tries to gain direct access to the display buffer (which includes an option present in nearly every modern player) will be slow.
Video editors, as they have the same choice of video output methods as video players do, also are influenced by this.
More drivel:
Some video cards (e.g. stuff from ATI) also include on-board circuitry to aid in producing a better video image. You'll see phrases like "accelerated DVD playback", "improved video playback quality", etc. on video board boxes. Sometimes it's just marketing drivel, but sometimes it really does refer to something significant.
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One more thing: The video card plays another role when it comes to, well, viewing video, which obviously has a lot to do with video editing.
Video cards represent color using only so many bits per pixel -- the maximum these days, for all practical purposes, is 24-bit color. (32-bit color doesn't give you any more colors.) 24-bit color, three components (RGB) = 8 bits per pixel. When you start doing complex blends, you can lose some color fidelity. (Of course, add more bits, like the Matrox Parhelia does, and you lose less fidelity.)
This is currently more of a problem in realtime 3D than it is in video editing (as high-level video editors internally maintain large bit-spaces for mathematics on color values), but it's still a video processing issue, nonetheless.
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God knows I'm wrong on half of this, and I probably didn't answer the question in the first place.
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