I'm trying to test and experiment with quality settings in some x264 front end tools. There seems to be some debate about CRF vs. 2-pass encoding and which is better. I understand if you have a file-size target than 2-pass is better whereas the CRF will give you better quality control for an unknown filesize.
RipBot's lowest CRF value is 18 but can I manually input 15 and get even better quality or will it just default back to 18 when the encode happens?
Filesize isn't an issue and most of my blu-rays won't have video compression but my DVD collection is a little different. I've got several DVD's that were advertized as widescreen but were infact 2.4:1 AR movies letterboxed in a 4:3 frame. So playback on HDTV's leaves you zooming in as the only way to get a good view of the actual film while keeping people's faces looking normal. Some cropping/encoding will be necessary.
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Yes you can manually enter values; you're not limited to the drop down presets. CRF15 will give better quality (and larger filesize) than CRF18
On a side-note, will a 2-pass encode give a variable or constant bitrate?
And if you KNEW the output filesize would the 2-pass mode be a better choice for quality/GB?
By the way, you can set CRF as low as zero -- lossless encoding. But the file size will be enormous.
Last edited by jagabo; 8th Oct 2010 at 06:03.
1) NTSC DV uses YUV 4:1:1 chroma subsampling. x264 doesn't support that. You would have to convert to interlaced YV12. There will be some losses from that conversion.
2) Few playback devices support lossless h.264.
3) The resulting video will usually have a higher bitrate than the source DV. About 2x, in my experience.
x264 encoder, though not necessarily. The objective would be files that will playback on something like a WD TV Media Player.
Encoding time would not be an issue. I can even render the DV as uncompressed, 10-bit, 4:2:2 video (in Final Cut Pro X), and compress that to H.264, if you think there would be any point.
Sorry, I didn't notice this is a blu-ray ripping forum. I should post my last post elsewhere.
x264 --crf 10 --bff --sar 10:11 --output filename.mp4 filename.avi
The resulting files should be playable on most media players that can play h.264 mp4. And they will usually be smaller than the source.
That's just the video of course. You'll have to encode and mux in the audio separately. Or use one of the x264 front ends that handles audio along with the video.
* DV pixel aspect ratios (called sample aspect ratios in x264) :
NTSC 4:3: --sar 10:11
NTSC 16:9: --sar 40:33
PAL 4:3: --sar 12:11
PAL 16:9: --sar 16:11
I use 640x480 , recently rather 720x540 resize , not feeling good about to leave 720x480 and to set 4:3 NTSC aspect ratio by MeGui , I use DVXA SD HQ settings, CQ18.
from Vegas timeline:
QTGMC( Preset="Slow" )
Lanczos4Resize(640,480) #or 720x540
very good result, the only problem is possible pixelation in very dark areas, shades, dark gradients, is there a way to consolidate it within MeGui ? CQ ussualy sets bit rate very well, but in this case it is the only problem that doesn't look like original after close look
Perhaps this setting would help him more directly. It was created for just this purpose. I read about the predecessor settings on Doom 9 in Dark Shakiri's comments on the issue of blocking. The blocking in flat and dark areas was a major annoyance for me I used Xvid much longer than I otherwise would have.
Adaptive Quantization Mode
Without AQ, x264 tends to underallocate bits to less-detailed sections. AQ is used to better distribute the available bits between all macroblocks in the video. This setting changes what scope AQ re-arranges bits in:
0: Do not use AQ at all.
1: Allow AQ to redistribute bits across the whole video and within frames.
2: Auto-variance AQ (experimental) which attempts to adapt strength per-frame.
See also: --aq-strength
Adaptive Quantization Strength
Sets the strength of AQ bias towards low detail ('flat') macroblocks. Negative values are not allowed. Values outside the range 0.0 - 2.0 are probably a bad idea.
See also: --aq-mode
It has the same defaults in the latest version
--aq-mode <integer> AQ method  - 0: Disabled - 1: Variance AQ (complexity mask) - 2: Auto-variance AQ (experimental) --aq-strength <float> Reduces blocking and blurring in flat and textured areas. [1.0]
Can you tell me what size is your Current Monitor size!?!?
Using aq-mode and aq-strength I think he'll have to set the strength to about 2.0. But I'm not using the latest release of AviSynth. Maybe things have changed.
Last edited by jagabo; 13th Feb 2012 at 20:14.
The defaults were good enough to stop the blocking for me.
I suppose AviSynth could be a source of blocking but it has nothing to do aq-mode as that is a x264 setting. Unless I am missing something.
I have looking over some threads on doom10.org, Dark Shikari's 'I am pissed at Doom9' site and a number of the problems some have had is that they disabled the aq-mode and then wondered why they got poor results.