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View Full Version : Is x264 deterministic?


madoka
3rd August 2005, 22:01
This is a follow-up to this thread (http://forum.doom9.org/showthread.php?t=97536).

What I mean is given the same input and settings, does x264 guarantee the same output every time (assume raw stream output)? Empirical evidence suggests that it is the case with --no-asm, but what about with assembly optimizations?

By the end of the before-mentioned thread, I was convinced that I had faulty hardware. So I ran the standard suite of stress test tools--memtest86, Prime95, SuperPI--but they all gave negative results. In contrast, I couldn't even get x264 to generate matching output for a 20-frame input!

Of course, just because my machine passed the diagnostics doesn't imply that it's not faulty. However, assuming that the answer to my question is the affirmative, then this makes x264 the most sensitive stress test tool I know. Maybe the devs should consider writing another stress tester based on x264. ;)

Sirber
3rd August 2005, 23:52
Faulty CPU? MMX unit overheat ;)

madoka
4th August 2005, 01:09
Faulty CPU? MMX unit overheat ;)
I did ran burnMMX for a few hours (I ran Prime95 & memTest86 overnight), and the machine didn't crash. I didn't run it overnight because it doesn't give any indication if the test computations are valid or not (aside from the machine not crashing).

If you know of another program that tests MMX specifically and verifies its computations, please let me know.