Stereo Tool

Happy New Beta, oops new Year!!!!!!!!!

LOL!


By the way, despite the new numbering, I wasn't planning to reach even 2 digits. This should just be a few minor fixes - including something to improve low latency sound, if possible.

I found a page with interesting info about the low latency issue. (See the image in the middle of the page, that really looks like Stereo Tool output for very low bass from a lot of versions ago).

http://www.katjaas.nl/FFTwindow/FFTwind ... ering.html

His solution looks like mine, but it has one big advantage: He can use the ideal window type twice, while I use a squared version of it. The disadvantage of his method is that the CPU load would double.

Ow, another important thing (I'll edit the post with remarks a few posts back): Don't use clipping for the lowest 3 multiband bands, or you'll get 'distorted' bass sounds (no high frequency artifacts, but like a subwoofer that's overdriven). There's no way to solve that at such low latencies.

Or at least use very little of it (the more clipping occurs, the worse the sound gets).


So the complete list of settings is now:

At latency 512, for good results, set:
- Highpass filter to Automatic selection or Never phase linear
- Phase Rotation either OFF or (around) 700 Hz, 5000 Hz, 3 rotations, 99.8%
- Loudness: 'Increase dynamics' to +15% (or higher) - ONLY needed for 512 (which probably indicates a bug in the latency 512 filtering). Setting it very high gives MORE artifacts at higher latency settings!
- Don't use clipping for the lowest 3 multiband bands, or you'll get 'distorted' bass sounds (like a subwoofer that's overdriven). There's no way to solve that at such low latencies. Or at least use very little of it.

I still need to check why the Increase dynamics setting helps.

About 'Increase dynamics': I only need to set it to 1% to get rid of the artifacts. Which makes sense; 0 it treated (slightly) differently from all other settings. And apparently better.

A similar effect (although far weaker) is also present at latency 1024 - so probably at all latencies. But it's only really noticeable at 512.

Edit: Yup, also (but weaker again) at 2048.

So there's apparently a bug in the default (increase dynamics = 0) handling. More than one actually - looking at this code I see that certain other filtering settings are ignored if this value is NOT set to 0...

Now EITHER this bug is a good thing - and I need to change the filtering always - or I need to fix it and get rid of the cracking noises in all situations.

Aha! The cracking is caused by Punch!

And worse: If you enable 'Increase dynamics'... Punch is disabled which decreases the dynamics - oops

Punch is doing exactly what it was made to do... But:

1. Multiband changes the audio, due to which it doesn't neatly fit in the 'windowing' function anymore.
2. Then the limiter cuts off the spikes that have appeared on the sides. Which is what it's supposed to do.
3. Then Punch detects that a lot of audio has been removed - and attempts to restore it... -> Artifacts.

I'll fix Punch so that it ignores soft tones (artifacts).

New build is running with 2 changes:
- Small change to the processing window. Theoretically this should be slightly better - but I couldn't notice any difference.
- Punch artifacts: They were caused by _soft_ sounds that were boosted by Punch. I've now set a threshold value, anything below that value is NOT Punched. You might need to increase the Punch level a bit to get similar results as before. Note that this affects ALL latency settings (and also removes artifacts from all of them!)

If the new Punch behavior is less good than the old one, please let me know - I can make the threshold dynamic so it goes down when possible - and at higher latency values that would make it respond nearly identical to that of version 6.00. But... The whole idea of Punch was that it operates on LOUD tones, so the new behavior might actually be slightly better. I'm not really sure here...


Edit: I think I may have also found a fix for the phase rotation filter. It will take some time to implement it, but that fix should completely remove all the artifacts that it currently causes. I think...

BETA601-002:
Winamp DSP plugin: http://www.stereotool.com/download/dsp_ ... 01-002.exe
Stand alone version: http://www.stereotool.com/download/ster ... 01-002.exe
VST version: http://www.stereotool.com/download/vst_ ... 01-002.dll
VST version (No SSE2): http://www.stereotool.com/download/vst_ ... 01-002.dll
Command line version: http://www.stereotool.com/download/ster ... 01-002.exe
Linux command line version: http://www.stereotool.com/download/ster ... ETA601-002 [not available]
Linux GUI version: http://www.stereotool.com/download/ster ... ETA601-002 [not available]

Important: Punch might be slightly less effective. If needed, increase the slider slightly. If the sound from Punch itself sounds less good, let me know and I'll make something closer to BETA601-001 which still protects against Punch artifacts.

To get good sound at low latencies (512, mainly):

• Highpass at 30+ Hz, not phase linear. (Default setting 'Automatic' is good). Tones below 30-40 Hz are still not handled very well (and that probably won't change)
• Phase rotation OFF or VERY VERY smooth (480, 5000, 3, 99.8%)
• Don't use clipping for the lowest 3 multiband bands, or you'll get 'distorted' bass sounds (like a subwoofer that's overdriven). There's no way to solve that at such low latencies. Or at least use very little of it.

Note: Setting 'Increase dynamics' above 0% is no longer needed with this version.

I don't notice any difference, but I probably don't have the soft sounds needed to test with... I went ahead though and bumped Punch up to 80% from 75% and increased the peak deformation from 85 to 90 in theory of less artifacts, that I couldn't really hear anyway, but that might just be my non-professional hearing...

I've been working on a preset that is a combination of the things that many people have done in their presets. I may post that soon, but the whole limiting and loudness stuff is a part that I'm kinda just fiddling with. So, in a somewhat off-topic question, how much clipping should you really see in Multiband, and does that end up contributing to additional artifacts once it gets to the loudness section?