X264 CUDA vs X264

[ben45]

Hello
I have read some old articles and topics about GPU x264 encoding. Is x264 CUDA encoding quality lower than x264? How much is that quality difference?

[jagabo]

Are you asking in general about h.264 encoding with Nvidia's hardware encoder vs x264? Or are you asking specifically about the version of x264 that includes some hardware encoding vs. pure software x264?

Note: h.264 (aka AVC, MPEG 4 part 10) is a specification for video compression. x264 is one particular encoder that encodes to that specification.

[poisondeathray]

There is no x264 CUDA.

CUDA is a programming language used by Nvidia cards.

Nvidia had an old CUDA h.264 encoder on older cards, but it was replaced by NVEnc in newer cards and drivers which uses a separate dedicated silicon for encoding/decoding functions, not "shaders" or "Cuda cores".

There was an open CL x264 patch which accelerated some x264 functions and overall speed by a few %, but the quality was slightly lower

[jagabo]

In general, all the hardware h.264 encoders deliver lower quality than x264 (at a given bitrate). And x264 at the "veryfast" preset is almost as fast as the hardware encoders and still delivers better quality.