Video Tab - Constant Quality slider

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Vietwoojagig
Posts: 49
Joined: Thu Dec 17, 2009 8:38 am

Video Tab - Constant Quality slider

Post by Vietwoojagig » Fri Sep 05, 2014 10:16 am

In the encoder options of the video tab, there is a preset slider.
If you change the slider, on the right you get the information "ultrafast, super fast, ..., very slow, placebo"

I suggest, that you do similar in the constant quality slider, e.g.
"RF 51-40: Really Bad, .. RF26-24: Worser, RF 23-22: Good (HD), RF 21: Good (SD+HD), RF20-19: Good (SD), RF18-16: Better, ... RF10-0: Insane (useless)"

I think this could help people to understand what the slider is about, and what they should select.

musicvid
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Re: Video Tab - Constant Quality slider

Post by musicvid » Fri Sep 05, 2014 2:14 pm

The RF numbers are relative, and have no direct correlation to YOUR perceived results with YOUR material.
RF 28 gives PERFECT results with a straight-cut slideshow, but not likely with an action movie.

Vietwoojagig
Posts: 49
Joined: Thu Dec 17, 2009 8:38 am

Re: Video Tab - Constant Quality slider

Post by Vietwoojagig » Fri Sep 05, 2014 3:14 pm

Well this might be true, but in Handbrake's own documentation (https://trac.handbrake.fr/wiki/ConstantQuality) a suggestion is given, what RF value is a good starting point (SD: 20 +/- 1, HD 22: +/- 1) and what values are usually useless (<19). Why not make these recommendations clear in the application.

In other programs it is quite usual to propose a "normal" setting that suites 90% of the cases and it clear that for the other cases you have to try another value if the result is not good enough or if the size is too big. But people will not try to encode a file with three different settings if the outcome is not obviously problematic and the first try is already nearly perfect.

Anyway, without reading the documentation, the RF slider does not tell you that 0 produces big files and 51 small files. At least this should be clear in the application.

musicvid
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Re: Video Tab - Constant Quality slider

Post by musicvid » Fri Sep 05, 2014 6:34 pm

I told you why. All video and all viewing is different. Wildly different.

You are reading way too much into a "suggestion."

Vietwoojagig
Posts: 49
Joined: Thu Dec 17, 2009 8:38 am

Re: Video Tab - Constant Quality slider

Post by Vietwoojagig » Sat Sep 06, 2014 9:35 am

1. "Anyway, without reading the documentation, the RF slider does not tell you that 0 produces big files and 51 small files. At least this should be clear in the application."

2. I don't read too much into a suggestion. You provide presets with RF setting of 20 or 22. What else is a preset more than a suggestion for a certain device. What do you think people do with a preset "Android Tablet" if a persons wants to encode for an Android Tablet, even if the material is widely different. They will use the preset as it is, and only try other value if the result obvious is too big or too bad. Do you really think people will watch an entire movie again to find the problematic parts that might need a better setting?

3. What you say is this: "You can choose RF values from 0 to 51 but we don't tell you which value makes sense and which value not, because your material is so special and your perception is so different from most of the the others in the world around, that you really cannot ask us. Sorry."

4. Please let the people around participate from your experiences about RF settings already in the slider, even if it will not work for everything.

5. Or alternatively: provide check-boxes: HD/SD, action movie, documentation, home video, grainy movie, animation, .... and then calculate a "suggestion" of an average good RF value.

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JohnAStebbins
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Re: Video Tab - Constant Quality slider

Post by JohnAStebbins » Sat Sep 06, 2014 2:19 pm

RF values are very much personal preference. The presets HandBrake supplies use RF 20 because it is usuall a nice tradeoff between quality and filesize. There are lots of people that think RF20 doesn't provide enough quality and bump that down to 18. And there are lots of people who think RF20 is overkill and bump it up to 24. So there is a range that probably extends from 16 to 26 that you could label with "good enough" or some such nebulousness. But every person you ask is going to have a different opinion about what RF20 means.

Until very recently I had a popup that would warn the user if the RF was outside the range of 16 to 30 because I considered anything outside that range silly. It's either crap quality (IMO) or enormous filesize. Turns out there are people that were happy using values outside that range and my popup just annoyed them. So we have imperical evidence that RF values have different meaning to different people.

Vietwoojagig
Posts: 49
Joined: Thu Dec 17, 2009 8:38 am

Re: Video Tab - Constant Quality slider

Post by Vietwoojagig » Sat Sep 06, 2014 3:04 pm

OK, accepted.
But then please update the help in the https://trac.handbrake.fr/wiki/ConstantQuality with everything you just said here.

But one final question.
In the MP3 codec LAME you have quality settings V0 - V9. I once asked them, if it would help to tell the codec what kind of music you put in (Metal, Classic, Pop, Techno,...). They said that they don't need to know that, because the codec would just use more bits, if they need to. So a Vx setting will always produce similar quality, no matter what type of music you put in. For LAME they say V3 is transparent for most of the music, V2 just in case, V0 for paranoid.
If I understand you correctly, the RF value does not behave that way. RF20 will not produce similar quality, depending on the type of material you put in. The codec not just uses more bits to ensure the same quality level depending on the material.

musicvid
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Re: Video Tab - Constant Quality slider

Post by musicvid » Sat Sep 06, 2014 7:56 pm

I used the example before:
Slideshow with straight cuts = perfect at 250 Kbps.
Sports footage = often inadequate at 16 Mbps.
Chasing butterflies doesn't work with interframe compression. Not even a little bit.

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