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Low latency secondary input (microphone)
https://forums.stereotool.com/viewtopic.php?t=853		 Page 60 of 75
Author:  Kakoon [ Wed Mar 24, 2010 11:40 pm ]
Post subject:  Re: Low latency secondary input (microphone)
The extra low latency output mode is broken, stereo tool crashes when i turn it on.
Author:  hvz [ Wed Mar 24, 2010 11:43 pm ]
Post subject:  Re: Low latency secondary input (microphone)
Quote:
The extra low latency output mode is broken, stereo tool crashes when i turn it on.
I know, it's on my todo list. (And I posted it a while ago, but I understand that you're not reading every single post :-) )

I still need to transform the low latency mode to the new low latency style processing (so it will sound a lot better than it did before). It got broken when I reduced the memory usage. Non-SSE2 versions are also broken by the way, that's also on my todo list.
Author:  hvz [ Wed Mar 24, 2010 11:44 pm ]
Post subject:  Re: Low latency secondary input (microphone)
Here's another copy of the todo list (from page 51 :shock: )

TODO:
- Remove (small) remaining peaks in Final Limiter - they are a bit higher now due to the improved bass handling ■ OK
- Fix very bad Final Limiter quality in low latency settings. ■ OK, fixed. Equal to v4.22 now, but I think I have some more improvements that I can try...
- Beep sounds are not completely constant in volume when they come out - check why and try to solve it. ■ OK, was caused by Pre Limiter, also Highpass filter
- Fix Stereo Boost - I found that it's behaving very differently from what I expected, but I don't know why. ■ OK
- Fix Singleband compressor. ■ OK
- Fix Stereo Boost meter (shows wrong levels, too low - sound is ok though) ■ OK
- Theoretically the CPU load of BETA3 should be clearly LOWER than v4.22 (a lot of optimizations should reduce the CPU load) - but it's only 2% lower. Check why. (Answer: FM: Oversampling in BETA3A, on 2nd CPU in v4.22. Todo: But what about non-FM? - Answer: Multiband is processed twice in Overlap=0 mode! Impossible to fix. ■ DONE
- Improve Deep Bass Boost for higher frequencies (upto ~ > 100 Hz? Probably with a sliding scale?) See post Bojcha on page 40. ■ DONE
- Fix broken sound when FM filter is turned on without Multiband ■ DONE
- Loudness: Deep bass protection in Overlap=0 mode is less good than in Overlap>0 mode. ■ DONE; checkbox added to enable removing DC component (worse quality!)
- Figure out what the difference is between AGC and what I'm doing now, see viewtopic.php?f=18&t=720&start=20 (among others). ■ DONE
- Add separate processing for high frequencies in AGC filter to fix drop in highs when loud bass kicks in. Simple solution: Lows: Process same as now (total signal, then filter); highs: process same as now, but add a constant value for the lows (first filter, then add constant, then process, then remove constant). Make this configurable: For pumping this should be turned off (single channel should be used.) ■ DONE
- AGC: Add code to limit volume rise for high freqs too much above low freqs -> sounds really annoying and 'thin'. ■ DONE
- Attempt to improve the highpass filter in Overlap=0 mode. ■ DONE, choise between phase linear and non-phase linear.
- Fix highpass filter: Tests show that bass quality in Overlap=0 mode is better than in Overlap>0 mode. If that's the case, then the highpass filter should also be better. But right now it's not. ■ WAITING FOR FEEDBACK
- Fix Hard Limit in Overlap>0 mode (completely destroys the sound at lower latencies at the moment). Noise gate OK, Stereo OK, AGC OK, Multiband OK, Bandpass OK, Singleband OK, Limiting OK, Loudness OK, FM OK
- Make CPU load configurable in Overlap=0 mode: Noise Gate, Stereo, AGC, Multiband, Bandpass, Singleband, Limiting, Loudness, Hard Limit, FM ■ DONE
- Multiband: Highest band max volume must be 77.5% of that in v4.22 for the same sound, why? ■ DONE, was a bug
- Multiband/Output filter: Check order (compare with v4.22 after fixing the other Trumpet related issues). ■ DONE, moved lowpass filter at 400 Hz above lowpass frequency to before Multiband.
- Restore quality/latency display based on the new settings. ■ Mostly done, todo: check if Overlap>0 should still be supported. ■ NO, bass in Overlap=0 is better. This sometimes hurts mid-highs a bit (vibrating female voices). That should probably be solved by lowering the bass level (or clean/punch slider) a bit. But the difference is not big, and except for this Overlap=0 only has benefits (much lower CPU load and much better bass)
- Move benefits of Overlap>0 mode into Overlap=0 mode by changing the window shapes. ■ DONE, didn't really help (introduced either bass rumbling or higher frequency harmonics).
- Fix problem with ILDP (Loudness) if bass phases are different.
- Hard Limit high CPU load for low J_STEP values. ■ DONE, turned out to be a more generic problem. Current settings seem to give the best performance for all different latency settings.
- AGC causes pre-echos ■ FIXED, less steep filter used
- Improve AGC behavior: Lock high frequency channel to low frequency channel and make sure that its volume never gets lower.
- Improve AGC channel separation at lower latencies.
- Fix Multiband high frequencies cause all-frequency drop.
- Fix dual core IPP FFT
- Create memory manager for better performance ■ NO, bug in Intel FFT calls solved, now seems to be no longer needed
- Fix low latency de-emphasis (differs too much from normal de-emphasis) ■ DONE
- Check the interface for settings that are no longer used (for example "Multiband HQ").
- Disable output displays of filters that are disabled due to too low latency.
- Fix Hard Limit filter for Loudness/Final Limiter ■ DONE
- Check pre-ringing filter effect on Bass Boost (might cause distortion) ■ DONE
- Fix non-SSE2 version ■ DONE, must be tested on a Pentium 3
- Check if alternative pre-ringing filter gives a better sound (because it should also fix post-ringing) ■ DONE, works great so replaced the original pre-ringing filter
- Fix FM Calibration memory error (and if possible, reduce the latency) ■ DONE, apparently IPP writes 4 values ahead instead of the 2 that are specified, due to SSE2/3/4 optimizations. Latency not yet reduced, I'm saving that for a future version.
- Create new Low Latency output (original one isn't working anymore).
- Trumpet filter and distortion in female voices: Create a new Trumpet filter without distortion. ■ DONE
- Pre-ringing volume calculation is still wrong: It does not take Pre Emphasis (do before copying, or also on copied signal) and Multiband Equalizer (use maximum) into account! ■ DONE, sound changed though (2 dB more highs!). Fix to get roughly the same sound: Lower last band equalizer setting by ~ 20% (-2 dB)
- Add "Phase Rotator" usefull for microphone processing ■ DONE!
- Small performance jump (-7%) still present - try to reorganize new's. ■ DONE, most of it is solved by doing the IPP allocations in a large block. A small difference (~ 2-3%) remains.
- Fix ugly font by increasing the size in 2 steps: 1: Draw at maximum size (12x16); 2. Enlarge THAT to the wanted size. ■ DONE
- Load and save all the new settings to/from disk. ■ Winamp/Stand Alone DONE, VST DONE
- There's a bug report that no 2 Stereo Tool instances can be loaded in a VST engine, test that too. ■ DONE, not reproducable in VstHost. For now I treat this as a single report on 1 PC, won't solve it for version 5.00.
- Fix VST bug: List of presets is duplicated. ■ DONE, preventing loading multiple instances based on a single DLL now
- Bass Boost display in main window. ■ DONE
- Fix presets. (Phase Rotation on etc; use Bass Boost in FM Bass presets) ■ DONE (although more changes might be useful at a later stage)
- Bass Boost default values. ■ DONE, a bit lower than before, but sounds clearly better.
- Optimize drawing of WAVE (in FULL SCREEN mode now more expensive than the entire processing!) ■ DONE, still relatively expensive (1/3rd of earlier usage)
- Arrow in Presets menu must be wider and in full screen mode must not contain unfilled bars. ■ DONE
- Attempt to reduce CPU load by simplifying processing: Dualband simpler implementation (4%) ■ DONE, replaced by AGC, Stereo Boost simpler implementation (7%) ■ OK, no longer relevant with faster FFT, noisegate with less bands? (8%), combine Final Limiter with Loudness? (8%) - percentages is what these filters use NOW of the total CPU load in FM Loud Bass Europe mode, replace OvershootBands filter - possible performance gain is a lot lower.
- Different Normal Output sound when FM + Stereo is enabled. ■
- AM presets: Use Loudness instead of Final Limiter; add BASS BOOST presets.
- FM presets: Reduce highs clipping to increase clarity of sound.
- Fix Stereo Boost meter (stops after few/many minutes/hours of work)
- About box: Thanks to Bojcha, donate -> buy ("most is free software") etc.
- Increase copyright rate?
- Add Bojcha's new preset

Later:
- Add GATING to compressors (stop increasing volume when the input volume gets below a threshold, reduces pumping and very loud volumes after a period of silence).
- Add Pre-Emphasize for Normal Output (10,15,20,25us), useful for web streaming (?)
- "Do you really want to close ..." message in stand alone version :-)
- Add "LINK" checkbox for "phase differences" in "Calibrate FM transmitter..." (20Hz-10240Hz), [someone call it TILT] :) ■ NO, doesn't seem useful as different frequencies need different phase offsets.
- Enable separate loading and saving of FM calibration settings. ( viewtopic.php?f=16&t=1370 )
Author:  Kakoon [ Wed Mar 24, 2010 11:59 pm ]
Post subject:  Re: Low latency secondary input (microphone)
Quote:
Quote:
The extra low latency output mode is broken, stereo tool crashes when i turn it on.
I know, it's on my todo list. (And I posted it a while ago, but I understand that you're not reading every single post :-) )
Haha okay, i gave up after browsing back a couple of pages to see if it was included. Good to see you've got everything covered. :)
Author:  hvz [ Thu Mar 25, 2010 12:28 am ]
Post subject:  Re: Low latency secondary input (microphone)
Tonight's update:
- Fixed Hard Limit problem in all situations now
- Fixed a bug in Bass Boost that could cause both bass distortion and pre-ringing. (*)
- Fixed some minor issues in the interface

Uploaded as BETA3:
Winamp DSP plugin: http://www.stereotool.com/download/dsp_ ... _BETA3.exe
Stand alone version: http://www.stereotool.com/download/ster ... _BETA3.exe
VST version: http://www.stereotool.com/download/vst_ ... _BETA3.dll (*)

(*) Only fixed in Stand Alone and Winamp plugin versions, not in VST versions. Will post a complete fix tomorrow.
Author:  Bojcha [ Thu Mar 25, 2010 3:23 am ]
Post subject:  Re: Low latency secondary input (microphone)
Something is wrong with Normal Output (standalone).
FM Output is OK!
Author:  hvz [ Thu Mar 25, 2010 9:04 am ]
Post subject:  Re: Low latency secondary input (microphone)
Quote:
Something is wrong with Normal Output (standalone).
FM Output is OK!
Will check tonight. In Winamp Normal output is fine... What should I hear? (I'll probably hear it tonight, but just in case I cannot reproduce it so I know what to look for).

I did notice that one of the volume output bars indicates the wrong output level for the pre-emphasized signal (apparently it displays the output level after multiplication by the FM output level?!) if I enable both FM output and normal output in the Winamp version.


Edit: I haven't checked yet, but I'm guessing here... Way too little highs? I just realized that you're probably using 176.4 or 192 kHz input sample rate, and that de-emphasis was previously done on the input sample rate. Now it's done on a downsampled version. I think I didn't change that, so de-emphasis is treating for example 5 kHz as if it's 20 kHz and de-emphasizing is very strongly.
Author:  Bojcha [ Thu Mar 25, 2010 12:29 pm ]
Post subject:  Re: Low latency secondary input (microphone)
no,
Output audio is just doubled, like two signals...
Quote:
Way too little highs? I just realized that you're probably using 176.4 or 192 kHz input sample rate, and that de-emphasis was previously done on the input sample rate. Now it's done on a downsampled version. I think I didn't change that, so de-emphasis is treating for example 5 kHz as if it's 20 kHz and de-emphasizing is very strongly.
Hmm, now you say something interesting...
At Stream PC i am usig 192kHz input (soundcard) with VAC set to fixed 192kHz for output. Reason is that i did not have such good highs as at transmitter PC .. so i switched from 48kHz to 192kHz (soundcard+vac). So, all the time was that internal de-emphasis ??

48kHz nand 192khz, whether it should be the same?
Author:  hvz [ Thu Mar 25, 2010 12:34 pm ]
Post subject:  Re: Low latency secondary input (microphone)
Quote:
Hmm, now you say something interesting...
At Stream PC i am usig 192kHz input (soundcard) with VAC set to fixed 192kHz for output. Reason is that i did not have such good highs as at transmitter PC .. so i switched from 48kHz to 192kHz (soundcard+vac). So, all the time was that internal de-emphasis ??

48kHz nand 192khz, whether it should be the same?
That's odd. When you're streaming(no FM signal, so no FM pre-emphasis and de-emphasis used!) I would expect much better highs. 48 or 192 kHz _should_ be identical; 192 might have a slightly higher (!) latency.

Will check the double output tonight.
Author:  Bojcha [ Thu Mar 25, 2010 12:41 pm ]
Post subject:  Re: Low latency secondary input (microphone)
Quote:
That's odd. When you're streaming(no FM signal, so no FM pre-emphasis and de-emphasis used!) I would expect much better highs. 48 or 192 kHz _should_ be identical; 192 might have a slightly higher (!) latency.
FM is OFF as should .. and i agree 48 and 192 must be indentical audo (in this case) but it's not, long time ago.
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