vbv-bufsize?

[AntiJw]

Hey,
I wonder, does image-quality get less good when going from
--vbv-bufsize 50000
to --vbv-bufsize 40000? I'm not sure what very high vbv-bufsize values are good for.
I primary want to do DXVA-encodes, but if I can get Blu-ray-support without any visual loss of image-quality, then I can do that.

[Sharktooth]

encode for blu-ray (using blu-ray settings). DXVA will be capable to play it back correctly.
bufsize wont change picture quality.

[Guest]

bufsize wont change picture quality. Unless you make it too small and get buffer overflows, which can cause freezes or dropouts. x264.exe will give you warnings if they are encountered. Don't ignore these warnings.

[AntiJw]

Thanks, I'll try
--vbv-bufsize 40000 --vbv-maxrate 40000
I mostly only do 1080p and 720p. I hope --vbv-maxrate 40000 is enough for all 1080p-encodes, otherwise I'll do --vbv-bufsize 40000 --vbv-maxrate 50000 and just hope for DXVA/PCH/Blu-ray compatibility :)

[shon3i]

You must use --vbv-bufsize 30000 --vbv-maxrate 40000 if you want to stick to Blu-Ray specs. With this setting you sould don't have any problem with DXVA aslo. And --vbv-maxrate 40000 is definitly to high for any 1080p video and max for blu-ray, aslo i never saw any retail Blu-Ray have --vbv-maxrate over 33000 coded with AVC. --vbv-bufsize 30000 is max for Blu-Ray, but you should use little smaller buffer for example --vbv-bufsize 29500 to leave room for overflows, because x264's VBV mehanism isn't much stable.

[AntiJw]

@shon3i: Thanks for the advice. I know some Blu-rays have very high bitrate-peaks, but those are an exception. I think I'll check bitrate of the Blu-ray before encoding (also look at bitrate-checker):
http://www.blu-raystats.com/Stats/Stats.php

maybe I'll go only for DXVA & PCH-compatibility if it peaks too high. Also, Blu-ray seems to want other options as well (according to MeGUI) "--keyint 24 --min-keyint 2 --ipratio 1.1 --pbratio 1.1 --qcomp 0.5 --mvrange 511 --aud --nal-hrd --sar 1:1".