Query regarding conversion to h265 using ffmpeg

[GeoffWA]

I am using ffMediaMaster over ffmpeg to compress some video files. I set up parameters for a conversion and processed a file noting the fps processing rate was low. I realised I probably hadn't checked use GPU. So I reran the processing only changing the flag to use GPU and as expected it processed much faster but unexpectedly produced a file with a video bitrate 4 times greater as well as corresponding increase in file size.

I was expecting a similar result since all other parameters were constant, can anyone enlighten me on why the results between the two processing routes are different?

[videoAI]

@GeoffWA

try:
Best Video Converter, not sure if x265 is supported.
it is a bit outdated but it uses FFmpeg, and allows for batch conversion too.

[pandy]

I was expecting a similar result since all other parameters were constant, can anyone enlighten me on why the results between the two processing routes are different?

As you not providing details then replay can be only general - GPU encoding is limited when compared to CPU encoding - there is many reason for this - HW broadcast quality encoders are very complex solutions and as such very expensive - GPU encoders provide basic encoding.
Well known fact is best HW GPU encoders are provided by NVidia and Intel, latest generation of their GPU HW provide higher quality then previous generation. Use newest software (drivers) - check recommended settings (and limitations) for your GPU HW.