x264 Number of threads to enable

[avs34]

Hi all this is my first post.

I just upgraded my old P3 to a P4 duel core and was wondering about the number of threads to enable in x264. Right now I have it set to 2 threads. Does x264 auto detect the cpu settings or can I go higher?

From what I have read in the forms it sounds like most people are using 2 threads. Just wanted to make sure.

Thanx

[Sirber]

Match the number of CPUs (real + virtuals) your system have.

P3: 1
P4: 1
P4 + HT: 2
PD: 2
PDE: 4

[Sharktooth]

no autodetection is done. however if your CPU has BOTH hyperthreading AND is a dual core then 4 threads are needed. If it is ONLY a dual core OR it has ONLY hyperthreading then 2 threads are enough.

[Sirber]

RealAnime does that for you :)

[avs34]

Wow ok thanks for the fast replies. I'll leave it set to 2 threads then.

thanks

[MeteorRain]

anyway, multi-thread doesn't matter even if you have only 1 core w/ HT. but it may cost a little overhead.
IMHO

[Mutant_Fruit]

2 threads won't provide any noticeable benefit unless you have two real cores. I remember reading that some guy here got slightly slower speeds when using 2 threads on a HT CPU.

[MeteorRain]

HT always do something surprising.
HT seems performs well in the situation that you play 3D game while encoding videos = =|||

[Sharktooth]

weird... i recall to have tried HT with 2 threads and the gain was from 10 to 30%.
can you try another movie source?

[HookedOnTV]

I was intrigued so I did a little test with a small file and MeGUI. Got a box with dual Xeon 2.66GHz processors (each with HyperThreading).

1 thread - 7.7fps
2 threads - 9.53fps
3 threads - 9.77fps
4 threads - 10.16fps