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x264 'Normal' preset question

Sep 16, 2013 at 9:37 PM

I'm looking to transcode some of my dvd collection with Vidcoder.

Looking at the 'Normal' profile it seems to be defaulting to the x264 very fast preset. First of all, is this correct and should it provide sufficient quality for playback on a tv or do I need to tweak anything?

I'm looking to do batch converting over night so I need the encoding speed to be fairly quick but not at the expense of any noticeable quality. If the only real issue is bloated file size then I can live with that. I don't really have a fast enough processor for one of the slower presets to be a viable option.

Also, when i've experimented with Vidcoder in the past i've always used an RF quality of 20 but that was using the 'medium' x264 encoding speed. Would it be worth lowering the RF to something like 18 to compensate for the faster encoding speed?

Any suggestions would be appreciated. Its been such a long time since I transcoded anything and I assume x264 encoding is more finely tuned than ever now.
Sep 16, 2013 at 10:18 PM
Yes, the x264 Preset is the setting you use to reduce encoding times. Since you're using Constant Quality, faster presets will increase the file size. The quality will stay the same though, so you shouldn't worry about changing the RF.
Sep 17, 2013 at 1:36 PM
That's interesting. So using crf the quality should be the same for normal and high profiles?

I ask because on my PC's the high profile takes twice as long, and I was using it most of the time, perhaps, in the mistaken belief, that it would produce a better quality encode.

So the only reason to use the high profile (when using crf) is because it produces smaller files?
Sep 17, 2013 at 3:37 PM
Yeah that's right.
Sep 17, 2013 at 6:30 PM
Thanks for your help,

So just to clarify, other than encoding speed and end file size there is no real difference in end quality between the very fast preset compared to say faster, fast and medium presets?

Just out of interest, why does Vidcoder now use the very fast preset? The old version I had always used x264 medium preset.
Sep 17, 2013 at 8:19 PM
Edited Sep 17, 2013 at 8:19 PM
I just did a test on a 10 minute video. The normal profile actually produced a SMALLER file. than the high profile. 229mb v. 271 mb for high profile. All other settings were at default (except no 2nd audio stream ac3 passthrough on high profile).

That seems to go against what you were suggesting. Any ideas why?
Sep 17, 2013 at 9:04 PM
Correct, the quality will stay the same when you change presets. Quality should only change when you modify the quality target.

VidCoder used to use the Medium preset but had a few extra advanced options which approximated the Very Fast preset. Now it just uses the Very Fast preset natively.

The file size difference is quite odd, since I'd expect when using the High profile and a slower preset the file size would be lower. Can you reproduce this on HandBrake? There may be a bug with x264 or something.
Oct 8, 2013 at 2:11 PM
Edited Oct 8, 2013 at 2:14 PM
Preset high turns on Decomb which adds filesize if the source is interlaced and and as you said a second audio stream. So no supprise high has an overaul bigger filesize than Normal. If either turning off or on Decomb for both Normal and High encodes and enableing or disableing the extra passthrough audio stream for both encodes, High will be smaller than Normal.

RandomEngy, I'm not sure I agree quality stays the same at the same CRF accross different presets, in my own testing that isn't true and other people have said it's not the case aswell.

Here for example:

Also to compare the quality difference between Presets you have to fix the bitrate otherwise it's not a fair comparison.
Oct 8, 2013 at 3:49 PM
Edited Oct 8, 2013 at 3:49 PM
Good info to have; guess I was wrong about CRF. I think the differing quality for the different presets must be the culprit here, since in his case the audio settings were the same.