1-Pass Quality

[erspicu]

Is there any plan for adding 1-Pass Quality with X.264 encoder ?

[berrinam]

It's already there -- it's known as QP mode.

[bond]

actually constant quant is no constant quality imho

the bitrate mode can be seen as a constant quality 1 pass mode

[akupenguin]

the bitrate mode can be seen as a constant quality 1 pass mode
yes, with "--ratetol inf".

[Mnl]

Ok - I'm a bit confused now... I have always been of the impression that constant quant resulted in constant quality - at least it is so for Xvid, isnt it?

How come this is different for x264, and what value of --ratetol correspond to constant quality?

[bond]

Ok - I'm a bit confused now... I have always been of the impression that constant quant resulted in constant quality - at least it is so for Xvid, isnt it?no, same in xvid as in x264 as in any codec

How come this is different for x264, and what value of --ratetol correspond to constant quality? read aku's post

[DarkZell666]

Hi !

I have a question regarding this "ratetol" switch :
In x264vfw (or x264gui.exe), does "bitrate variability = 100" actually mean "--ratetol inf" ?

Or does it really mean "--ratetol 100", and that constant visual quality is only available through cmdline ?

[bond]

I have a question regarding this "ratetol" switch :
In x264vfw (or x264gui.exe), does "bitrate variability = 100" actually mean "--ratetol inf" ?

Or does it really mean "--ratetol 100", and that constant visual quality is only available through cmdline ?it means --qcomp 60
--qcomp <float> QP curve compression: 0.0 => CBR, 1.0 => CQP [0.60]you cant set the ratetol via x264vfw and x264gui, but in x264gui you can save the .bat file and after that add --ratetol inf yourself to it and than execute it (for starting the encode)

[Mnl]

@bond:

I hope this isn't too dumb, but the reson why I asked for the value for --ratetol is that when I use "--ratetol inf" I get the following message:

x264 [error]: bitrate tolerance too small, using .01

What am I doing wrong?

[akupenguin]

Did I never apply the workaround for win32's broken atof()? anyway, try rev 286.

[Mnl]

It works perfectly with rev 286. Thanks a lot :)

[omion]

So, if I'm not trying to fit the movie to a certain size, is there any point in doing a 2-pass encode? Does 1-pass with --ratetol inf do everything that 2-pass does in terms of quality?

I ask this because I have no interest in fitting movies to any particular size, and if I can actually get a 2-pass quality movie in 1 pass that would be awesome.

[edit: just searched around a bit more and found that 2nd pass determines the I-frame quant based on the following scene. Are there any other differences?]