GPU video transcoding image quality - NVIDIA CUDA versus AMD Stream
 

After spending quite some time looking at performance when using various video editing and transcoding applications with GPU-based acceleration in recent weeks, we now turn our attention to the question of image quality, using Cyberlink's MediaShow Espresso to investigate how the use of both NVIDIA's CUDA and AMD's Stream functionality compares to using good old-fashioned CPU processing in terms of the quality of video files output by the application.


Looking at this frame from a pretty typical scene, with a solitary person and a small amount of movement, we can get an early idea of transcoding quality in such a relatively simple environment. Encoding to the iPod, all three of our encoding methods (CPU, CUDA and Stream) offer up pretty good image quality here, but look a little closer and you can already spot differences between them - Overall, our CPU-based encode provides the sharpest image, with our NVIDIA part not far behind (with only a very slight loss of detail in paces), while the output from our Radeon HD 4870 is noticeably "softer" and lacking in detail. If you focus on the woman's face and skin, these differences start to become more marked, even at this low resolution.

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