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.


Go Back   Doom9's Forum > Video Encoding > MPEG-4 AVC / H.264

Thread Tools Search this Thread Display Modes
Old 27th December 2014, 11:40   #1  |  Link
Registered User
RRD's Avatar
Join Date: Nov 2009
Location: France
Posts: 20
Does --ratetol have any effect on a x264 --crf encode without VBV?

Hello. I just realized I forgot to remove --ratetol 8.0 in my x264 encoding command line after doing some tests with --bitrate encodes, which means I've encoded my recent videos with both --crf and --ratetol in the command line. Does it have any negative impact? The wiki (excerpt below) doesn't mention anything so I assume it has no effect, but you never know. Also I'm NOT using any --vbv setting. Thanks.

Default: 1.0

This is a dual purpose parameter:
  • In 1-pass bitrate encodes, this settings controls the percentage that x264 can miss the target average bitrate by. You can set this to 'inf' to disable this overflow detection completely. The lowest you can set this is to 0.01. The higher you set this to the better x264 can react to complex scenes near the end of the movie. The unit of measure for this purpose is percent (eg, 1.0 = 1% bitrate deviation allowed).

    Many movies (any action movie, for instance) are most complex at the climatic finale. As a 1pass encode doesn't know this, the number of bits required for the end is usually underestimated. A ratetol of inf can mitigate this by allowing the encode to function more like a --crf encode, but the filesize will blow out.

  • When VBV is activated (ie, you're specified --vbv-* options), this setting also affects VBV aggressiveness. Setting this higher allows VBV to fluctuate more at the risk of possibly violating the VBV settings. For this purpose, the unit of measure is arbitrary.
RRD is offline   Reply With Quote
Old 27th December 2014, 12:27   #2  |  Link
Registered User
Join Date: Jul 2007
Posts: 552
No. It doesn't have any effect (not used) in case of CRF without VBV except writing different ratetol value to SEI with settings. With VBV it would have some effect.
MasterNobody is offline   Reply With Quote

crf, ratetol, x264

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT +1. The time now is 11:26.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.