[Attachment 63029 - Click to enlarge]
is there anything fast first pass and slow first pass?
if yes then whats thier advantages and disadvantages?
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Anonymous543Guest
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Using a slower first pass means that a more accurate 1st pass will be used.
Depending on the encoder and content this might have small benifits in regard of compression ration.users currently on my ignore list: deadrats, Stears555 -
iirc. it should work with:
Code:--x265-params pass=1:slow-firstpass=1
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Anonymous543Guest
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Unlike x264, in x265 the default is to use a fast 1st pass, so: no
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Anonymous543Guest
btw slow first pass vs. fast first pass which will give better video quality?
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slow first pass is more precise and could potentially preserve more details from the source, whether it does or is just a waste of time depends on your source and your settings,....
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Anonymous543Guest
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Skript based frame works for filtering content.
users currently on my ignore list: deadrats, Stears555 -
Ah, I mixed it up before.
x264 uses fast first by default and x265 doesn't.
To know for sure you need to look at the source code in ffmpeg.users currently on my ignore list: deadrats, Stears555 -
Anonymous543Guest
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There is a simply way to know: try whether pass=1low-firstpass=1 slows things down or not,...
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Anonymous543GuestCode:
ffmpeg -y -i input.mp4 -c:v libx265 -b:v 100k -preset ultrafast -x265-params pass=1 -f null NUL && ^ ffmpeg -y -i input.mp4 -c:v libx265 -b:v 100k -preset ultrafast -x265-params pass=1:slow-firstpass=1 -f null NUL && ^ ffmpeg -y -i input.mp4 -c:v libx265 -b:v 100k -preset ultrafast -x265-params pass=1:slow-firstpass=0 -f null NUL && ^
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to state the obvious: Why not simply use a longer souce? (at least I don't plan to spend time searching through ffmpegs source code to varify something that you can easily test)
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Anonymous543Guest
soo... i changed preset to slow and results are.....
Code:ffmpeg -y -i input.mp4 -c:v libx265 -b:v 100k -preset slow -x265-params pass=1 -f null NUL && ^
Code:ffmpeg -y -i input.mp4 -c:v libx265 -b:v 100k -preset slow -x265-params pass=1:slow-firstpass=1 -f null NUL && ^
Code:ffmpeg -y -i input.mp4 -c:v libx265 -b:v 100k -preset slow -x265-params pass=1:slow-firstpass=0 -f null NUL && ^
looks like slow first pass is enabled by default for ffmpeg libx265(hevc) but still for confirmation i'll make one more thread on it. -
Anonymous543Guest
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x264 uses fast first by default and x265 doesn't.users currently on my ignore list: deadrats, Stears555
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Anonymous543Guest
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https://x265.readthedocs.io/en/master/presets.html with preset medium shows the defaults that are directly changed through presets.
Looking through the option https://x265.readthedocs.io/en/master/cli.html you can also see for each option it's default value.
Also like jagabo mentioned you could also simple do a encode and look at the output with MediaInfo to see the settings that were used,...
Cu Selur
Ps.: this seems to be going in circles, I'm off this thread, but I wish you luck in your endevours.users currently on my ignore list: deadrats, Stears555 -
You could just read the docs:
https://x265.readthedocs.io/en/master/cli.html?highlight=slow-first-pass#cmdoption-slow-firstpass -
Anonymous543Guest
Damm it was in documentation , and i was just wasting my time in doing weird tests and all ,anyways thank you selur and jagabo
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