Stereo Tool

"Test Right Channel" in "FM Transmitter Calibration" does not work since v6.10 (standalone)

BETA038:
The declipper is now functioning again, with automatic clipping level detection. It is not yet finished, because I'm now just marking ALL samples at a margin below the peak level as clipped - and that's not good.

There is a new filter added that makes the declipper more resilient against too low clipping detection levels.

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 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.

To be done: ONLY mark samples above the threshold as clipped if they also APPEAR to be clipped according to my previous clipping detection algorithm.

Note: The current version should already outperform what we showed on the Omnia 9 at the NAB in Las Vegas - because of the new filter. (Clipping level detection is probably very similar, and so is the margin slider).


Winamp DSP plugin: http://www.stereotool.com/download/dsp_ ... 20-038.exe
Stand alone version: http://www.stereotool.com/download/ster ... 20-038.exe
VST version: http://www.stereotool.com/download/vst_ ... 20-038.dll
VST version (No SSE2): http://www.stereotool.com/download/vst_ ... 20-038.dll
Command line version: http://www.stereotool.com/download/ster ... 20-038.exe
Linux command line version: http://www.stereotool.com/download/ster ... ETA620-038 NOT AVAILABLE
Linux GUI version: http://www.stereotool.com/download/ster ... ETA620-038 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
- Finish declipping filter (clipping level detection + level reduction in dB). 2 days
- Update presets? (BASS_AGC etc.) 1 day
- Finish blind interface
- Add AGC start level
- "Test Right Channel" in "FM Transmitter Calibration" does not work since v6.10 (standalone) (bojcha)
- Channels L/R swap in stand alone version when changing filtering/quality (?) (eldoradofm)
- 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

I don't see new slider (margin) in De-Clipper, and not hearing automatic clip level detection

edit:
I tryed De-Clipper with that 'metalica' track and much better with is with help of phase rotator.

The phase rotator in Stereo Tool *should* be after any declipping though. Declipping happens before anything else, or it doesn't work properly to remove as much distortion as possible.

I suppose it is possible that you're using an external rotator before it, and that for some freak chance it works better on 1 song out of many thousands.

@ Bojcha: Oops - the stand alone version Loudness window isn't updated (again...) - I guess I should remove the optimization that I performed that introduced the difference between the two, because I keep forgetting this.

What do you mean by that phase rotator remark? What does it improve? Declipping is the first thing that happens in Stereo Tool. Phase rotation is near the end and should have no noticeable effect on the audio...

When i set the Quality / Precision slider to 16, i get highs distortion with the extreme clipped track.
It's noticeable right at the beginning of that track.

I noticed that too. Something is still wrong there, because it *should* sound much better (try the U2 track at the end of the extreme clipped sample, and listen to the distorted 'S' sounds).

This wasn't the case before, so I suspect the new filter that I added to remove distortion - which does work very well in cases where no distortion was present at the start.

I notice a bug. When i open a preset sometimes left and right get swapped. Best way to check this is changing buffer size with mouse wheel. Then even when the number doesn't change left and right swap. See input and output meters on the attachment.
I tested it with the stand alone version and with ASIO on and off and both times i have this problem.
EDIT: I also tested it with winamp version there it's ok.

I just tested that track with De-Clipper + Phase Rotator, so PR is after De-Clipper. If i look at scope, things looks better and i think sounds better.
But, again this is maybe only good for this track.. multiple clipping levels in original.. etc...

@Bojcha: Ok, clear. It makes sense that it looks better, however you should not be able to hear any difference (neither here nor with normal not-clipped audio).

@eldoradofm: Hm, will check... Given the description I think this problem must also be present in all previous versions...

@Bojcha: Will add your 'FM Calibration' remark to todo list.