x264: Encoded videos need lots of CPU to play

Question

My computer (Intel Core 2 Duo T9300, 2.5GHz) can usually play any Full HD file, and Blu-Rays perfectly.

However, when I encode a Full HD file myself, the CPU is struggling and frames are dropped.

Here's my command line:

ffmpeg.exe -r 24 -f concat -i list_of_png_files.txt -i w:\audio.wav -acodec copy -c:v libx264 -preset medium -b:v 10000k -shortest output.avi

I tried adding -maxrate 13000k after "-preset medium". However, x264 doesn't seem to honor this - the framerate still reaches 20MBit at parts.

How can I encode videos in such a way as to reduce CPU usage during decoding?

Answer 1

There is an x264 tuning option for exactly this purpose. I believe -tune fastdecode is what you are looking for. But this will disable some compression features, so the video may not look as good without increasing the bitrate.