[FFmpeg-devel] ffmpeg multithread decoding, the rate is not improved

[艾薇妮]

Hi!
 I'm trying to decode .264 file using ffmpeg with -threads option,i'm  using a dual-core computer and build ffmpeg using the pthread option,but   the rate is not improved,i wonder what is the reason.
 my command line is:
 time ./ffmpeg -y -threads 2  -thread_type slice -i test.264 test.yuv
 and 
 time ./ffmpeg -y -threads 1 -i test.264 test.yuv 
 the time is close,i didn't see any improvement.
 i tried to encode and transcode video using -threads option,i can see  great improvment about twice speed improvent ,why does the multithread  decode is not good?
 i would be so much appreciated that if you  can answer me this question!