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DXV profiles

Posted: Wed Jun 27, 2012 00:35
by mfo
Hey Guys
Occassionally we had problems with DXV's compression. It is normally connected to dark subtle gradients. I did some test and could reproduce the issue.
The original consists of some subtle gradients, saved lossless. DVX compressed (screenshot from Resolume's output) it looks like this:

In some real situation, lets say: slow camera pans, these compression articfacts get even more visible as they result in aggressivly jagging lines while the actual movie animates in a restrained way. Especially in a cinema situation on a nice, crisp HD projector, the situation can get quite messy.
Here is a real-live screenshot:
(In this one also canon dslr compression artifacts come into play .. it is not dxv alone ;))

Anyway, I know that compression algorithms have to balance multiple factors - filesize, performance as well as quality. Hence hues get less well compressed then brightness, and darker areas less then mid-range-brightness areas (?). Thus I would not call the above a bug, rather a worst-case-scenario.

So, here comes the idea: introduce compression profiles for dxv!
Aside from the default profile (dxv as is), there could be one that compresses the darker parts very well, another one with a generally low compression (resulting in huge files), maybe even one for black/white only.

What do you guys think, is that possible?


Re: DXV profiles

Posted: Thu Jun 28, 2012 10:17
by Joris
Everything is possible ;-)

But..... The main idea behind DXV is 'one ring to rule them all'. We wanted to make a codec that just works, withouth the need to have a degree in applied compression algorithms. Introducing profiles would take away form that simplicity.

I'll toss it around the office though.

Re: DXV profiles

Posted: Thu Jun 28, 2012 17:51
by mfo
I know, and this a quality I like about DXV.
What I had in mind was to preserve the simplicity, just add some flexibility - via self-explanatory serving-your-needs profiles, intead of a million of options. And if you dont feel the need to change things, you can keep everything as is (via some sort of Default profile).

Re: DXV profiles

Posted: Fri Feb 08, 2013 02:19
by lbens
Hey, I also have to say I'm totally unhappy with the DXV codec. Resolume is a great bit of software but the compression is just not up to scratch in terms of quality. Particularly noticeable with slow moving or graphical footage. Smooth diagonal lines get jaggy aliasing, soft blurred or glowy images on dark backgrounds get severe artifacting/banding.. In the end HD footage ends up looking like 640x480 res blown up to scale. For me, with the shows I'm currently involved in, it's actually unacceptable and for this reason alone I would need to go back to VDMX or similar where I can at least plays back the much cleaner AIC codec without problems.
DXV really needs to catch up with the tech people are using -HD footage is now standard! And it needs to look like HD! Or resolume should be capable of playing back minimum 3 layers in AIC (or similar) without slowing down. Otherwise your great software becomes obsolete (at least for my purposes).. and that's really sad! You've put so much work in to make it a brilliant tool - but without great looking footage, it stops being a viable option.
Sorry, don't mean to sound too negative, just played a high profile overseas gig and feeling frustrated about this topic - instead of feeling proud of my work I felt ashamed at the codec quality problems; and that's the killer.
Thanks for listening.. :)

Re: DXV profiles

Posted: Fri Feb 08, 2013 12:25
by pfelberg
It doesn´t sound like we are gonna have any change/upgradess on this soon ; (

Re: DXV profiles

Posted: Fri Feb 08, 2013 14:33
by kmifflin
This something I've posted about this before. I will admit that the concept of DXV helped win me over from other softwares. I love that it uses the GPU. But I've had multiply events were clients were unhappy with the with the artifacts and colour shift that encoding to DXV causes. I generally run ProRes LT when it needs to be HD.

The concept of keeping it simple is interesting, but you must know how to convert their media in an application like compressor. Adding a hd and sd profile should add to confusion.

Have faith in us the users. If we are wise enough to trust resolume with our clients contents then I think we can handle a quality setting.

Re: DXV profiles

Posted: Mon Feb 11, 2013 11:44
by Joris
There are two issues at play here.

The first is the simplicity of the codec:
Although we have full trust in you when it comes to compression options, the problem is the communication of these options. Already in this thread it's becoming problematic as the issue is not HD vs SD or the quality setting of DXV, it's the compression algorithm used.
Similarly to how you ask for trust in your compression skills, we ask you to trust us when it comes to deciding what makes good user experience and what could lead to confusion.

The second is the compression algorithm:
We actually have been experimenting with this, and a new version with decreased filesizes and better alpha compression is on it's way.
However, the problems described in this thread are inherent to the compression method used, and can't be solved by using a quality slider or introducing profiles.
DXV is designed to balance speed and quality. If you see quality problems, we advise to switch to ProRes or AIC. This quality increase will then naturally go at the expense of speed though.

Thirdly, as a personal side note: mentioning the need to switch to another software comes across as vaguely thuggish. Let's be perfectly clear, the only thing we care about is the quality of your show. If you feel you cannot reach the quality level you're after, no one is forcing you to keep using Resolume. Mentioning a possible switch to another software does nothing to help the discussion move forward or improve the issue at hand.

Re: DXV profiles

Posted: Mon Feb 11, 2013 14:13
by kmifflin
It's good news to hear that you may have a updated DXV, the smaller file size is appealing considering my new ac book pro only shipped with 128 gb ssd. Fortunately any time I have to use ProRes to playback I'm generally only snag a single layer for playback. Would adding adding a two pass encoding process increase the quality?

Re: DXV profiles

Posted: Mon Feb 11, 2013 15:14
by mfo
thanks for the insight answer joris.

a little remark from my side: neither file size nor performance have been a problem for me so far. so i would happily trade these for a better image quality. i understand that other people might have other priorities, hence it's an idea to introduce profiles to keep things simple.
(ProRes would go too far, it does cause problems. and there is no AIC for qt under windows. so, a new dxv with ... oh well, you guess it ;))

looking forward to the new version!

Re: DXV profiles

Posted: Mon Feb 11, 2013 17:27
by Joris
We can change the algorithm used for compression to have higher quality output. At that point file size becomes five times as big as it is now though, and you're better off just using ProRes.

We'll probably be changing the playback method of AIC and ProRes files in one of the 4.x updates, as we may have found a way to speed it up considerably.