Stereo Tool

Stereo Tool 6.10 is available!

Changes:

Reduced latency:
# Latency: ASIO: Add processing priority control to enable very low sound card latency (~ 1-3 ms) without hiccups; total latency of ~ 16 ms possible.
# Latency: Upsampling (for FM) and downsampling (for high input sampling frequencies) no longer causes extra latency.
# Latency: Reduced Composite Limiter latency from 1.7 ms to 0.9 ms at latencies 512 and 1024. Some (very small) effect on audio.
# Latency: Found a bug that caused hiccups in audio processing, fixed it. Results in lower possible latency.
# Latency: Pushing data to the output before the processing instead of afterwards to reduce latency.
Improved audio quality at low latencies:
# Dynamically adjusting audio processing windows at low latencies to better match the type of audio that comes in.
# Dynamically adjusting clipping effectiveness to avoid clipping 'too much' in certain conditions, depending on audio processing window and audio content. This protects soft highs against horrible vibration caused by bass sounds at latency 512 and (less) 1024.
# Upsampling and downsampling: Far less artifacts caused, far cleaner output signal.
# Created alternative Phase Rotation filter for low latencies (512, 1024).
# Multiband: Added an 'artifact protection' step that limits the maximum difference in reduction between adjacent bands, if they cause too much (configurable) artifacts.
# Multiband: Adapted frequency bands and band content to make Multiband at latency 512 sound as much as possible as higher latencies.
# Loudness: Disabled Improved Bass Distortion Protection filter for latency 512 because it caused distortion.
# Loudness: Fixed vibrations caused by Very deep bass distortion protection at latency 512 and 1024. Now also enabled for latency 512.
# Hard Limit: Fixed (minor) artifacts in upsampled audio.
# Bass Boost: Reduced artifacts at latency 512. Note: Using a less steep filter (bigger difference between frequencies) helps!
Other changes:
# Loudness: Improved Punch filter: Now causes far less artifacts than before. But it is less effective for soft sounds.
# Loudness: Removed distortion caused by Punch.
# Bass Boost: Removed distortion.
# Quality and Latency are now part of presets, and STS files.
# Bug fix: Loading and saving Noise levels in VST version resulted in incorrect behavior.
# Bug fix: Displayed Multiband output levels were unreliable at low latencies, especially clipping.
# Bug fix: For high input sample rates, now removing very high frequencies that cause issues with Hard Limit.
# ASIO: Added ASIO Configure button, which allows setting ASIO parameters such as ASIO buffer granularity.
# ASIO: Changed buffer size configuration to match whole ASIO grains.
# Added and updated a number of presets.

I installed it this evening. It installed clean, came up with my WinAmp installation, and did a fantastic job.

I will have to do a little more testing, but I did detect a cleaner sound especially in the deep bass.

HVZ,
Your software gets better everytime.

Thank you!

I have been using stereo tool for such a long time now i cant seem to listen to music or videos without it.

but yes.....thank you Hans for all your hard work on stereo tool... it has come a long way and gets better and better.

beats any sound processor I know.

donation may be cumin your way soon Hans...ill let you when i have sent it.

ah,,
Found bug! Standalone (dsp not checked)
Bug in Steepness (Prevent Artifacts - checkbox):

4096 - "Prevent Artifacts" ON, set to some low number 10-20%, Steepness OFF, but it's still ON !
To turn it off: Set to 250% then "Prevent Artifacts" On and OFF.

Confirmed. When reloading ST, it's ok - fortunately...

Will fix it in the next version.

Hans, is this possible :
viewtopic.php?p=9397#p9397
Or would this be too complicated (MB GUI elements ?)

Hans,
I've been thinking hard about the AGC. If I recall correct, in a prior debate over AGC action, you did mention about probable ways to make the AGC more responsive or aggressive- something like 2pass AGC.
I am reiterating the need for it, if it is really possible to implement it. Reason I ask is this- the avg loudness that we can achieve by setting AGC to nominal/default values (0.8/10.0) in conjunction with Loudness set at 2.00, the same can be achieved with a more aggressive AGC and Loudness at 1.5. Loudness above 1.5 tends to morph the bass in tracks consisting of clipped bass or slamming bass(Timbaland etc).
So I was wondering if your 2pass AGC or may be a better look-ahead algorithm could do the trick?

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Phoenix: After reading your post: Maybe instead we need a 2nd AGC that ONLY operates on bass. Why? Because then it could be set far more aggressively without affecting the rest of the audio. On top of that, it would greatly reduce the current ('steepness') artifacts in Multiband, bass boost and Loudness at low latencies, if I let it operate on - say - everything below 300 Hz or so (that requires far less steep filtering than Multiband which starts with a band that ends around 80 Hz). This may result in reduced bass levels in the output though. Alternatively it could be put AFTER multiband - only if a lot of bass remains there it would kick in (for higher latencies that's ok, for lower it would cause the multiband artifacts to re-occur).

Or: Further improved bass protection in Loudness (I've improved it a lot already in version 6.00, but I could set it more strict).

Phoenix: Just a quick check to see what it does.
Winamp DSP plugin: http://www.stereotool.com/download/dsp_ ... 20-001.exe
Stand alone version: http://www.stereotool.com/download/ster ... 20-001.exe NOT AVAILABLE
VST version: http://www.stereotool.com/download/vst_ ... 20-001.dll
VST version (No SSE2): http://www.stereotool.com/download/vst_ ... 20-001.dll
Command line version: http://www.stereotool.com/download/ster ... 20-001.exe
Linux command line version: http://www.stereotool.com/download/ster ... ETA620-001 NOT AVAILABLE
Linux GUI version: http://www.stereotool.com/download/ster ... ETA620-001 NOT AVAILABLE

Extra low frequency AGC added directly after current AGC. (Actually it might be better to place it AFTER multiband.)

Note: This also reduces bass artifacts at low latencies! (For that it must be placed BEFORE Multiband!)


- Stand alone version not available because I'm in the process of adding an interesting new stand alone feature...
- I hear some artifacts at low latencies that I didn't expect. Will have to check what's causing it.
- 'Remove remaining peaks above' for new 2nd filter still uses setting for 1st filter!


Edit: Hint: Good settings seem to be:
- Up speed: ~ 175
- Down speed: ~ 500
- Target output level depends on Multiband settings (if you select 'LIMIT' instead of 'COMPRESS', it makes little difference - lower = less artifacts at low latencies).

At low latencies, it also helps a lot (also in 6.10 by the way) to reduce 'But never raise band 2 more than' - for example to 200%. The bigger this difference is, the more artifacts the AGC can cause (ok, it's not the main source of artifacts - but with this new filter the Multiband and Loudness artifacts are reduced a bit, and the AGC artifacts are noticeable).

Hans, I downloaded the beta... though I'm yet to check it. Will do so tonight. Hence, I can't comment on how effective this approach of AGC is for now.
However, I wanted to know why can't we go by the convetional course that most hardware rigs take i.e. a slow wideband AGC and follow it up with a multi-band AGC(something that Stereo Tool already has) but more aggressive. You're the best to understand the challenges involved in implementing this, but I think it's very feasible.

Anyways, I'm taking a leaf out of my last nights experimentations. I'd be pleased to gather opinion from you, Bojcha, Michi or for that matter anyone who has been in this forum long enough. And this concerns the Multi-Band. I'd annotate a point at a time to reach out to you...
I figured out that if there's one sections that's accountable for StereoTool not really as transparent as other rigs, it's got to be the Multiband. And before dismissing the claim that software based MB dynamic processing can't achieve that kind of transparency, I tested ones from Izotope and Waves. Results from mere 4 bands of compression with 6dB of Loundess are FAR BETTER than that of processed recordings of major rigs like Orban-8600 etc.
Also from a user's perspective, configuring StereoTool MB is the most daunting task. Thats one reason why everyone creating a preset starts with the default settings provided in StereoTool which means that any preset sounds only selectively good but never clean.
1. It'd be good if you'd callibrate the 'soft-limit' threshold in dBFS rather than a linear scale of 1~10.
2. Same holds true for callibration of 'Attack' and 'Release' times in milli-secs rather a linear scale.
3. Provision for setting up the compression ratio by user(this also takes care of what Bojcha previously suggested) for each band, with provision for LIMITING. This is important because, as of now to callibrate MB we first decide what shape to give to the sound from a band and simultaneously set 'soft-limit' threshold to achieve desired GAIN REDUCTION for that band. This approach is not correct.
Instead we decide a nominal compression ratio that we want to start with and set the threshold so as to get the desired GAIN REDUCTION. After which we fine tune the attack and release settings to give the desired shape.
4. Implement instantaneous display of GAIN REDUCTION applied for a specific band. Right now it's pure guess work that if the scale if half filled(with CLIPPING DISABLED), a 6dB reduction happens. By implementing this, user will get visual cue as to how close he's to achieve the right spectral balance.
5. User selectable number of bands. Rather than defining Center Frequencies, allow them to define CROSS-OVER frequencies with (possibly) user defined 'Q' (rather than global Steepness Value)for that band. This should take care of artifacts that are generated.(also if possible to mute other bands at any instant except one the user is working on and BYPASS bands...these could be like little check boxes or radio buttons)
6. Instead of Equalizer, it's better to have 'Band Gain' for each band or may be both.

All in all, I am not asking for radical changes in MB processing action, rather a change in a how a complex processing stage like MB is presented to the end user. This is apt for a product like StereoTool if it's to seriously contend with $10,000 rigs. There's no rush to implement. You can write the implementation in parallel with on-going development. But I'm certain the features if implemented would be very well received by the users.

Opnions, counter-opinions most welcome.

BTW, the Loundness callibration - is it dB(RMS)?(been thinking of asking this several times, but used to forget, so...)

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