Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion. Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules. |
|
|
Thread Tools | Search this Thread | Display Modes |
19th October 2020, 21:09 | #1 | Link |
Registered User
Join Date: Oct 2001
Location: Germany
Posts: 7,259
|
Should x264 be non-deterministic when '--non-deterministic' isn't used?
Over at videohelp, there is someone you get's non deterministic output even when he isn't using '--non-deterministic'.
Some folks say that: a. x264 is always non-deterministic as soon as multithreading is used. b. x264 is always non-deterministic as soon as VBV is used. c. x264 is always non-deterministic as soon as VBV&multithreading are used together. I though that x264 should be deterministic as long as '--non-deterministic' isn't used and if it isn't there is a bug? Also when a., b. or c. is correct, what is the use of '--non-deterministic' ? Can someone knowing the code answer this? Cu Selur |
20th October 2020, 04:22 | #2 | Link |
Registered User
Join Date: Feb 2002
Location: San Jose, California
Posts: 4,406
|
I always believed a was true. Since the relative performance between threads is non-deterministic the code would need to wait for unencoded blocks it expected to be complete but I don't believe it does.
Of course, I am not someone knowing the code.
__________________
madVR options explained |
20th October 2020, 04:31 | #3 | Link |
Registered User
Join Date: Apr 2018
Posts: 61
|
According to the x264 mailing list from 2015, vbv+multithreading is intentionally non-deterministic.
https://mailman.videolan.org/piperma...il/011035.html |
20th October 2020, 05:09 | #4 | Link |
Registered User
Join Date: Feb 2002
Location: San Jose, California
Posts: 4,406
|
There isn't much in the way of why there.
Is it only non-deterministic for case c then?
__________________
madVR options explained |
20th October 2020, 18:27 | #5 | Link | |
Moderator
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,752
|
Quote:
I've done HUGE amounts of x264 tuning over the last 10+ years, and I don't think I've ever had a need to use deterministic mode. |
|
20th October 2020, 20:25 | #7 | Link | |
Registered User
Join Date: Feb 2002
Location: San Jose, California
Posts: 4,406
|
Quote:
I do have --non-deterministic in all my command lines but I am still curious.
__________________
madVR options explained |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|