Stereo Tool

Ah, ok, 2 issues:
- Expected max input slider: Just a slider configuration problem. Fixed.
- Difference with sound of 052a: Half time didn't work.

Now half time was still introducing a lot of weird sounds (which Bojcha complained about), I think I now have a solution that is nearly as smooth as half time but without those weird sounds. Will be available in the next BETA.


If everyone agrees with this I can perform a big simplification on the Natural Dynamics filter which will also reduce its CPU load and memory usage.

BETA055:
Still BETA052A based.
- Scopes background made black
- Added AGC start level
- Natural Dynamics behavior repaired (was broken in BETA054) and improved!

BUG FOUND: Natural Dynamics uses the volume AFTER performing Pre Amp. That's wrong. And has a BIG impact on the audio.
BUG FOUND #2: Declipper disabled waveform display.

Previously, in BETA052A-based versions of Natural Dynamics, there were some metallic reverb-like sounds present (because a small bandwidth area got a boost and then the volume was reduced slowly, causing frequencies in such an area to be boosted even though they were not very loud anymore).

This new version is a bit smarter: It looks ahead a bit, and if not much sound it present in the near future, the volume is dropped much faster.

So for voices (for which this slow volume drop was added), it still works as it did before. But for transients the volume is dropped extremely rapidly.

The DIFF signal now sounds *much* better.

If everyone now agrees that the _sounds_ in Natural Dynamics (not necessarily the frequency contents) are correct, then I can remove the code that spreads out the effect over adjacent bands and speed up the code - probably a lot.

From the previous beta (still valid):
The CPU load is also pretty high because I'm calculating 32 different tilt levels to find the best match (so automatic tilt detection works, but it needs serious optimization).

New slider: "Declipping margin" - if you set this to 75%, everything above 75% of the maximum level is considered to be potentially clipped.

Changed slider: "Never consider samples to be clipped if they are lower than:" - rule out soft sounds, whatever they look like, they are not clipped.


Winamp DSP plugin: http://www.stereotool.com/download/dsp_ ... 20-055.exe
Stand alone version: http://www.stereotool.com/download/ster ... 20-055.exe
VST version: http://www.stereotool.com/download/vst_ ... 20-055.dll
VST version (No SSE2): http://www.stereotool.com/download/vst_ ... 20-055.dll
Command line version: http://www.stereotool.com/download/ster ... 20-055.exe
Linux command line version: http://www.stereotool.com/download/ster ... ETA620-055 NOT AVAILABLE
Linux GUI version: http://www.stereotool.com/download/ster ... ETA620-055 NOT AVAILABLE

TODO:
- Fix loading changed multiband frequencies
- Add buffer and filter for SCA output (SCA1 ok, SCA2 ok)
- Finish AGC improvement - make mono value configurable (replace checkbox by slider) 1 hour --> NO, not needed - anything else needed? -> NO
- Fix Punch
- Check what to do with new filters (such as bass AGC) - keep them, remove them, change them? --> KEEP
- Save new BASS_AGC setting in VST mode
- Loudness: Annoying cracking sound in bass. Slightly present in 5.00, worse in 6.00, maybe even worse in 6.10. Only when bass is too loud. Much worse than in Final Limiter (at same input level!) - so this clearly indicates a bug. Most likely cause: The filter that was added to remove bass artifacts....... - No, it's the louder bass. But it can be fixed by changing some settings. Default settings updated, and behavior for 'not Very strict' improved. Also Deep bass boost and Very deep bass protection are enabled for latency 512 now.
- Fix crash at program close
- Fix VST plugin version (does not run)
- Dynamically drop 'Allow louder highs, even if it causes vibrations' to 0 when bass filter suspects noticeable voice vibrations. 1-2 hours
- Reduce Loudness CPU load days?
- Check and remove static variables
- Finish new de-essing filter (check what to do with the settings, remove at least some!) 1 day
- Convert Multiband input to MONO, then use arrays [2][4096] --> should give speedup. - FAILED
- Natural Dynamics: Fix or remove transient boost
- Natural Dynamics: Add expected + strength slider per band
- Finish declipping filter (clipping level detection + level reduction in dB). 1. Figure out why removal of unwanted frequencies causes flat lines at high quality setting with small overlap. This causes distortion, with this fixed repairs are MUCH better. 2. Fix MP3 correction, automatically scale down when this deteriorates the sound. --> TOP part fails!
- Declipping filter: Fix low latency behavior
- Always oversample clipping (configurable)
- Declipping filter: Change detection at lower input levels.
- "Test Right Channel" in "FM Transmitter Calibration" does not work since v6.10 (standalone) (bojcha)
- Declipper window close function - check! - Seems ok
- Scopes black background?
- Add AGC start level
- RDS issue reported here: viewtopic.php?f=15&t=3703&p=11524#p11524 partially solved
- Natural Dynamics: Smooth out different bands more to reduce low-bitrate-MP3-like sounds.
- Natural Dynamics: Optimize situation with no interaction between bands for performance.
- Declipping filter: Optimize tilt detection for performance
- Declipping filter: Optimize peak matching for performance
- Update presets? (BASS_AGC etc.) 1 day
- Finish blind interface
- Channels L/R swap in stand alone version when changing filtering/quality (?) (eldoradofm)
- Move pre-emphasis to end of processing 1 day
- Save all new settings, also through VST interface
- Change version number 1 hour
- Release 1 hour
- Add lowpass filter for stereo signal (will cause a lot of extra latency!) - it might be possible to avoid this latency using a Hilbert transform
- Add smarter clipping detection. Maybe something much simpler suffices: Current clipping detection with threshold + flat line detection
- Declipping filter: Automatically override the 3 clipping level sliders if the clipping level is detected very clearly (clear thin spike in sample value histogram). - NONSENSE, this is already done by the histogram function. But it can be made a BIT better - I think - by automatically LOWERING the 'always clipped' slider if a lot of data is present at the highest few bins (but care is needed for DBN - Jack is Back like tracks)

Hi Hans,
Most new filter settings are getting saved and reloaded in VST plugin.
Any plans for correcting the behaviours of 'Minimum attack speed near top' and 'Extra loudness - Advanced Highs Protection enabled' (in VST Plugin)?
What should be the optimal value or range for 'Startup input level'? Does it have any co-relation with 'Minimum attack speed near top' especially if I am using values > 1 for the latter?
And last, will I expect (theoretically) any performance or quality gain by enabling 'Oversample limiters' if I am using it for transcoding of audio files?

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BETA056:
Fixed the 2 bugs in BETA055.

From the previous beta (still valid):
The CPU load is also pretty high because I'm calculating 32 different tilt levels to find the best match (so automatic tilt detection works, but it needs serious optimization).

New slider: "Declipping margin" - if you set this to 75%, everything above 75% of the maximum level is considered to be potentially clipped.

Changed slider: "Never consider samples to be clipped if they are lower than:" - rule out soft sounds, whatever they look like, they are not clipped.


Winamp DSP plugin: http://www.stereotool.com/download/dsp_ ... 20-056.exe
Stand alone version: http://www.stereotool.com/download/ster ... 20-056.exe
VST version: http://www.stereotool.com/download/vst_ ... 20-056.dll
VST version (No SSE2): http://www.stereotool.com/download/vst_ ... 20-056.dll
Command line version: http://www.stereotool.com/download/ster ... 20-056.exe
Linux command line version: http://www.stereotool.com/download/ster ... ETA620-056 NOT AVAILABLE
Linux GUI version: http://www.stereotool.com/download/ster ... ETA620-056 NOT AVAILABLE

TODO:
- Fix loading changed multiband frequencies
- Add buffer and filter for SCA output (SCA1 ok, SCA2 ok)
- Finish AGC improvement - make mono value configurable (replace checkbox by slider) 1 hour --> NO, not needed - anything else needed? -> NO
- Fix Punch
- Check what to do with new filters (such as bass AGC) - keep them, remove them, change them? --> KEEP
- Save new BASS_AGC setting in VST mode
- Loudness: Annoying cracking sound in bass. Slightly present in 5.00, worse in 6.00, maybe even worse in 6.10. Only when bass is too loud. Much worse than in Final Limiter (at same input level!) - so this clearly indicates a bug. Most likely cause: The filter that was added to remove bass artifacts....... - No, it's the louder bass. But it can be fixed by changing some settings. Default settings updated, and behavior for 'not Very strict' improved. Also Deep bass boost and Very deep bass protection are enabled for latency 512 now.
- Fix crash at program close
- Fix VST plugin version (does not run)
- Dynamically drop 'Allow louder highs, even if it causes vibrations' to 0 when bass filter suspects noticeable voice vibrations. 1-2 hours
- Reduce Loudness CPU load days?
- Check and remove static variables
- Finish new de-essing filter (check what to do with the settings, remove at least some!) 1 day
- Convert Multiband input to MONO, then use arrays [2][4096] --> should give speedup. - FAILED
- Natural Dynamics: Fix or remove transient boost
- Natural Dynamics: Add expected + strength slider per band
- Finish declipping filter (clipping level detection + level reduction in dB). 1. Figure out why removal of unwanted frequencies causes flat lines at high quality setting with small overlap. This causes distortion, with this fixed repairs are MUCH better. 2. Fix MP3 correction, automatically scale down when this deteriorates the sound. --> TOP part fails!
- Declipping filter: Fix low latency behavior
- Always oversample clipping (configurable)
- Declipping filter: Change detection at lower input levels.
- "Test Right Channel" in "FM Transmitter Calibration" does not work since v6.10 (standalone) (bojcha)
- Declipper window close function - check! - Seems ok
- Scopes black background?
- Add AGC start level
- RDS issue reported here: viewtopic.php?f=15&t=3703&p=11524#p11524 partially solved
- Natural Dynamics: Voices, especially in chorus, still sound weird.
- Natural Dynamics: Smooth out different bands more to reduce low-bitrate-MP3-like sounds.
- Natural Dynamics: Optimize situation with no interaction between bands for performance.
- Declipping filter: Optimize tilt detection for performance
- Declipping filter: Optimize peak matching for performance
- Update presets? (BASS_AGC etc.) 1 day
- Finish blind interface
- Channels L/R swap in stand alone version when changing filtering/quality (?) (eldoradofm)
- Move pre-emphasis to end of processing 1 day
- Save all new settings, also through VST interface
- Change version number 1 hour
- Release 1 hour
- Add lowpass filter for stereo signal (will cause a lot of extra latency!) - it might be possible to avoid this latency using a Hilbert transform
- Add smarter clipping detection. Maybe something much simpler suffices: Current clipping detection with threshold + flat line detection
- Declipping filter: Automatically override the 3 clipping level sliders if the clipping level is detected very clearly (clear thin spike in sample value histogram). - NONSENSE, this is already done by the histogram function. But it can be made a BIT better - I think - by automatically LOWERING the 'always clipped' slider if a lot of data is present at the highest few bins (but care is needed for DBN - Jack is Back like tracks)

If you're saving to an STS file I suppose?? I'll check ALL the new parameters before releasing version 6.20. The AGC will start with settings as if the input level was what's specified with this slider. Fully to the left = old behavior. Fully to the right = beep level at maximum level was played just before. What is the best setting really depends on the average level of the audio that you're playing. There's no relation with 'Minimum attack speed near top'. Say your input has the following values: 0, 20000, 32000, 32000, 20000, 0. Then if the sound card, Windows, CD player, ... upsamples it before playback, you might see something like this: 0, 12000, 20000, 27000, 32000, 33000, 32000, 27000, 20000, 12000, 0 - hence you get clipping even though all the samples in your waveform are below 32767. If you enable this Oversample thing, the waveform is adjusted such that upsampling later does not cause clipping.

So the answer is:
- If you got clipping before, your sound quality will improve
- If you didn't, it might deteriorate a bit because more clipping/limiting is performed. This should be a very small difference though.
- The CPU load with this enabled is higher.

Even though the 'roughness' in the signal is removed, if I crank up the strength of the Natural Dynamics filter I hear way too many weird things in voices. Needs looking into.

@Hans, thanks for the black background looks much better now.
Could you add some values to the AGC Startup input level slider like dB RMS or something like that so the setting makes more sense?

tnx for black background and stratup-AGC-level.

Movement of pre-emphasis soon? - I think that some testing is needed after this.

Isn't the 'Advanced Highs Protection' in Loudness Section supposed to do 'something'. I see no movement of the blue bar at all. Have already played like 30+ tracks in my playlist but it seems like fixated at just one level. In previous betas I used to see enough movement of the indicator to reflect that it's working. Is the filter itself not working or just the indicator that's having a glitch? I checked it using the VST plugin. Uncertain of the standalone and DSP versions.

The other thing, enabling and then disabling de-clipper makes Stereo Tool (VST plugin) play the text message even when unregistered options are NOT being used, that too every 2mins 30secs. Is this the intended behaviour?

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Put the Loudness slider at least one step to the right, that will activate the 'Advanced extreme Highs Protection'.

Hans: Does the AGC startup Lvl slider do something at all? Maybe it is just me, but i dont notice anything.