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Low latency secondary input (microphone)
https://www.forums.stereotool.com/viewtopic.php?t=853		 Page 9 of 75
Author:  Bojcha [ Thu Dec 10, 2009 1:59 am ]
Post subject:  Re: Low latency secondary input (microphone)
Hi Hans,

question,
Is it bad idea to create separate version of ST which will be LowLatency only and use only Asio ?
Author:  hvz [ Thu Dec 10, 2009 8:16 pm ]
Post subject:  Re: Low latency secondary input (microphone)
Well, I'm trying to combine the two. Which will eventually have benefits for both versions - even if you're not interested in very low latency playback, 68 ms is still better than the current more than 500 ms in version 4.22 (with THE SAME sound quality, at least that's the goal).

Basically I made a mistake in my initial implementation that has been there since version 1.0 - every processing step causes latency, even if it does not need to look ahead. For many filtering steps that can be fixed with NO effect on the sound, there are only a few (for example pre-limiter "remove remaining peaks") that currently look ahead a bit further and may need to be changed slightly. The noise gate, pre limiter and multiband compressor do NOT look ahead - which means that removing the extra latency should have NO effect at all. And for Loudness I've already checked (also using measurements instead of just relying on my ears) that there's almost no difference.

On top of this, I expect to be able to reduce the CPU load a lot with little effect on the sound quality - the Quality setting can be controlled far more accurately than is currently the case.
Author:  hvz [ Fri Dec 11, 2009 1:29 am ]
Post subject:  Re: Low latency secondary input (microphone)
Good news and bad news:

Good: Pre Limiter, Multiband (including clipping etc.), Stereo Boost, Noise Gate and Pre-Emphasis are now nearly identical in the new lower latency version. (There are differences, but not in quality).

Bad: The CPU load of Noise Gate + Pre Limiter + Multiband + Stereo Boost + Pre-Emphasis is 24% (!) higher than in version 4.22. Eek!

Lowpass/Highpass filter is not working for some reason (I'll need to check why).

Remaining issue: The "remove remaining peaks" filter, which requires a bigger look-ahead.

I hope to be able to have something usable (that I can post here) by tomorrow.
Author:  hvz [ Sat Dec 12, 2009 2:40 am ]
Post subject:  Re: Low latency secondary input (microphone)
I will post a more-or-less useful version in about an hour.

It's still buggy, but most filters are working (Pre Limiter "remove remaining peaks" and Singleband compressor are not yet working at all, and the de-emphasis, used when listening to FM sounds on "normal output", sounds weird and swaps the channels).

Processing latency in normal latency mode: 68 ms + MPX processing latency
Processing latency in low latency mode: 17 ms + MPX processing latency

The 17 ms setting might be a bit too aggressive - but I've set it so aggressive to get some feedback... (Eventually it will be configurable).

There's some more good news: I mentioned earlier that the output of the Multiband compressor was slightly different than before - well that turns out to be a good thing: In the past, clipping and "post filter" caused some artifacts, especially in low latency mode. They are gone now!
Author:  hvz [ Sat Dec 12, 2009 4:23 am ]
Post subject:  Re: Low latency secondary input (microphone)
Winamp DSP plugin: http://www.stereotool.com/download/dsp_ ... _BETA2.exe
Stand alone version: http://www.stereotool.com/download/ster ... _BETA2.exe
Command line: http://www.stereotool.com/download/ster ... _BETA2.exe CRASHES
VST version: http://www.stereotool.com/download/vst_ ... _BETA2.dll

Notes (known bugs, there may be more):
- Pre Limiter: "Remove remaining peaks" does NOT work at all
- Singleband compressor: Make sure it's turned OFF, otherwise you might get very strange results (it's executed as the first processing step right now, so before anything else).
- When switching between normal and Low Latency mode, always restart Stereo Tool, otherwise you'll get a cracking sound.


"Low Quality" currently only has an effect on the Loudness filter, everything else currently ignores this setting.



The following filters are working:
- Noise Gate
- Pre Limiter except "remove remaining peaks"
- AZIMUTH corrector
- Stereo Boost, including "excessive reverb protection"
- Pre-emphasis
- Multiband compressor, including clipping. "HQ" has no effect anymore (and that will stay that way).
- Bandpass filter
- Final Limiter, except the "Reduced CPU usage" and "Avoid Distortion" switches. ("Reduced CPU Usage" DOES work when Loudness is also turned on).
- Loudness, including all bass protection filters (they probably don't work properly in Low Latency mode)
- Hard Limit

Partially working:
- Stereo Image. It does something, but the sound that comes out is very bad when the "phase" and "width" slider are not set to 1.00. ■ FIXED
- De-emphasis. It swaps the channels, it causes a time shift between the channels, and it seems to remove too much of the high frequencies. (This only affects listening to FM presets with non-preemphasized output. The actual FM output is not affected by this). ■ FIXED

Not working (my "TODO" list):
- "Channel delay" ■ FIXED
- Singleband compressor ■ FIXED
- Pre Limiter "remove remaining peaks" ■ FIXED
- Final Limiter "Reduced CPU usage" and "Avoid Distortion" switches ■ FIXED
- Bass protection on very low latency settings. (although it's not really bad either)
Author:  Bojcha [ Sun Dec 13, 2009 2:38 am ]
Post subject:  Re: Low latency secondary input (microphone)
Hi Hans,
How now all sounds better in "Low latency mode" then without "LowLatency mode" :mrgreen:

Overall This sounds much better now with LowLatency.
- I think Clipping in Multiband is better with lowlatency now, if i compare it with org.v4.22 without lowlatency. 8-)
- Final Limiter is good as always!
- StereoBoost is good too!
- BandPass much much better
- Loudness .. i can say good but sometimes is better to not use it if ILDP is not ON
- Pre limiter, for that i must listen more...

big big good progress ... !
Author:  hvz [ Sun Dec 13, 2009 3:58 am ]
Post subject:  Re: Low latency secondary input (microphone)
Update: Channel Delay, Singleband compression and De-emphasis are working now!


Some questions for Bojcha:
Quote:
How now all sounds better in "Low latency mode" then without "LowLatency mode"
Ehm, do you mean when you compare it with version 4.22, or when you turn Low Latency on and off in this new version? (Remember: ALWAYS restart the Stereo Tool beta after changing this setting, switching isn't working properly yet!)
Quote:
- Loudness .. i can say good but sometimes is better to not use it if ILDP is not ON
What do you mean exactly? Does it sound bad (worse than in version 4.22) when Improved Loudness Distortion Protection is turned off? And is that - in the new Beta - with Low Latency turned on or off?
Quote:
- Pre limiter, for that i must listen more...
It's identical to the normal latency Pre Limiter in version 4.22. Except that "remove remaining loud peaks" doesn't work.


The goal that I'm trying to reach is:
- Normal latency version of this new BETA2 must be AT LEAST as good as version 4.22, but with a much lower latency.
- Low Latency version of the new BETA2 must be AS CLOSE AS POSSIBLE to the Normal Latency version.
Author:  hvz [ Sun Dec 13, 2009 4:11 am ]
Post subject:  Re: Low latency secondary input (microphone)
Note: Just found another bug.

In the Final Limiter, if "Avoid distortion: ..." is enabled, a cracking sound is present. So make sure it's turned off...
Author:  Bojcha [ Sun Dec 13, 2009 8:59 pm ]
Post subject:  Re: Low latency secondary input (microphone)
Quote:
- Normal latency version of this new BETA2 must be AT LEAST as good as version 4.22, but with a much lower latency
First i did't know that you wont to make this too. I was think that Normal Latency will stay same and only LowLatency mode will be optimized.

Ofcourse i do restart after switching LL mode.

- Normal Latency in v4.22 compared to beta2 is better exept Clipping in multiband.
- Loudness in beta2 is good but Improved Loudness Distortion Protection must be always ON. if not strange bass distortion occures. it's not that
- PreLimiter is good, LL or non-LL.

- yes, Final Limiter's "Avoid distortion" makes crackle on right channel.
Author:  hvz [ Sun Dec 13, 2009 10:30 pm ]
Post subject:  Re: Low latency secondary input (microphone)
Hi Bojcha,
Quote:
- Normal Latency in v4.22 compared to beta2 is better exept Clipping in multiband.
Can you say what is worse in the beta2 than in v4.22? I have the feeling that the new beta2 sounds a bit "harsher", is that what you mean?

And if so, can you confirm that the difference is only in the Loudness filter? (If so, I can make a small part of the Loudness filter not Low Latency, that still greatly reduces the total latency and should restore the quality of v4.22)
Quote:
- Loudness in beta2 is good but Improved Loudness Distortion Protection must be always ON. if not strange bass distortion occures. it's not that
Odd, I don't hear any difference when I turn it on or off... Are you using one of the presets so I can compare it here?


Note: A new version is coming in about an hour, where "stereo image" and "remove remaining peaks" is fixed (and, "remove remaining peaks" seems to work much better than in version 4.22).
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