Hi,
I am trying to test the speed of different encoding options in x264.
1-First, I tried to see the effect of the number of reference frames. I got the following results for a 1280x800 video sequence, 25fps, 250 frames:
Code:
--ref 1 -> Average PSNR Y=40.79dB, Average fps= 9.7
--ref 2 -> Average PSNR Y=40.41dB, Average fps= 9.2
--ref 3 -> Average PSNR Y=40.80dB, Average fps= 8.8
--ref 4 -> Average PSNR Y=40.76dB, Average fps= 8.6
But it is strange for me. I expect to see higher PSNR values when using more ref frames. Unfortunately I cannot distinguish between the visual quality of the above cases. But what is the reason of it?
2- Is there any option for disabling/Enabling 8x16 and 8x16 macroblock partitions?
3- I used "--no-chroma-me". The encoding speed was increased but the average PSNR was decreased a little!! So, what is the reason of it?
Thanks!