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GT3b2 with HF Reduction, Proof of concept
QuantumKnot
post Feb 27 2004, 02:37
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Joined: 16-December 02
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I've included the HF boost reduction technique I used in QKTune beta 3.2 into the current GT3b2, as a proof of concept.

You can download the binary here:
http://www.hydrogenaudio.org/forums/index....ndpost&p=188227

The nice pre-echo handling of the original GT3b2 may be slightly worse. Start at -q 5 and compare this with the original GT3b1/GT3b2 and see whether the HF boost is there or not. smile.gif
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QuantumKnot
post Feb 28 2004, 02:43
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Group: Developer
Posts: 1245
Joined: 16-December 02
From: Australia
Member No.: 4097



Many thanks to guruboolez for his listening tests. The term 'reduce' is definitely the appropriate one here since I'm not really fixing the source of the problem but rather, trying to compensate for it which means my settings may not be optimal and more tuning is needed. Also, I only focused on reducing one type of HF boost.

Unfortunately, I have no answer at this time for how to fix the coarse and grainy noise that appears in classical music. I suspect there is no easy way of compensating for it (in a consistent way) and one will have to look into the code deeply. But after the experimenting I've personally done, there are a few things I discovered:

1. Most of these problems seem to have little to do with stereo coupling. I've replaced point stereo with lossless coupling and stilll, I get the HF boost. Nothing seems to be wrong with lossless coupling either since I've checked the coupling and decoupling code and everything should decouple right. Hence I believe point stereo is magnifying the problem but is not the cause of it.

2. Since the HF boost is present in both point and lossless stereo, then the source of the problem either lies in the floor generation, the floor removal, or the residue quantisation. I'm leaning towards perhaps the third process as being the cause since it is entirely consistent with what other people on the vorbis-dev mailing list suspect....unusually low SNR in high frequencies causing a high increase in energy due to quantisation noise.
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Posts in this topic
- QuantumKnot   GT3b2 with HF Reduction   Feb 27 2004, 02:37
- - guruboolez   I can't test it for the moment, but could you ...   Feb 27 2004, 03:31
- - QuantumKnot   QUOTE (guruboolez @ Feb 27 2004, 12:31 PM)I c...   Feb 27 2004, 03:40
- - guruboolez   The second one. When you said 'start at -q5...   Feb 27 2004, 03:43
- - music_man_mpc   QUOTE (guruboolez @ Feb 26 2004, 06:43 PM)Whe...   Feb 27 2004, 03:51
- - QuantumKnot   QUOTE (guruboolez @ Feb 27 2004, 12:43 PM)The...   Feb 27 2004, 03:52
- - QuantumKnot   QUOTE (music_man_mpc @ Feb 27 2004, 12:51 PM)...   Feb 27 2004, 03:57
- - harashin   Some results of mine. hustlejet at q5 castanets a...   Feb 27 2004, 05:20
- - QuantumKnot   Many thanks. Looks like GT3b2 is benefitting fro...   Feb 27 2004, 06:38
- - harashin   Megrim disappears now... Well, these ones include ...   Feb 27 2004, 08:11
- - QuantumKnot   Those are very encouraging results Did you hear...   Feb 27 2004, 11:34
- - harashin   QUOTE (QuantumKnot @ Feb 27 2004, 07:34 PM)Th...   Feb 27 2004, 12:28
- - QuantumKnot   Many thanks for your invaluable tests. Well, my s...   Feb 27 2004, 12:46
- - Cobra   Just make sure that Monty see this code (inform hi...   Feb 27 2004, 13:23
- - guruboolez   Iím in holidays, and I donít have access to my mai...   Feb 27 2004, 14:45
- - Big_Berny   QuantumKnot, I only want to thank you for all your...   Feb 27 2004, 21:28
- - QuantumKnot   Many thanks to guruboolez for his listening tests....   Feb 28 2004, 02:43
- - QuantumKnot   btw. Has anyone heard any change when raising the ...   Feb 28 2004, 09:33
- - nyaochi   QUOTE (QuantumKnot @ Feb 28 2004, 05:33 PM)bt...   Feb 28 2004, 11:07
- - harashin   As guys said, Brahms3 isn't hard to ABX to me,...   Feb 28 2004, 11:27
- - QuantumKnot   It's a very quiet sample and I started getting...   Feb 28 2004, 11:43
- - Biont   QuantumKnot, after all this testing, is your versi...   Mar 22 2004, 16:34
- - QuantumKnot   QUOTE (Biont @ Mar 23 2004, 01:34 AM)QuantumK...   Mar 23 2004, 00:45


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