CPU to GPU back to CPU

[Frank Maki]

The CPU sends a stream of instructions/data to the GPU and the GPU processes the stream and it puts the appropriate display on the screen. That is a one way stream from the CPU to the GPU. In video editing when the editing is complete it is necessary to export a video file.  The CPU can generate the video file by itself but it can produce it faster using the GPU. The question is how can the GPU help the CPU make a video file.

[Tabs]

The difference is basically where the data goes after being processed. Normal graphics-related data like what gets sent to the display, gets processed by the GPU and then gets sent via hdmi/displayport/DVI to the display to be converted into a picture that you can see.

 

With GPGPU tasks like video encoding acceleration, the result of the processing simply gets sent back to the cpu (to be saved to a file or otherwise worked on by the system). 

 

The processing speed of a gpu doing video encoding is so much faster than a cpu - in most situations - that even the extra time taken to transfer the data to the gpu for processing, and then back to the cpu for finalising, is still faster than the cpu simply doing it all itself. 

[Catsrules]

The same way the GPU displays data on the screen, the CPU sends instructions/data to the GPU, the GPU does that and sends back the results.