Stereo Tool
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Low latency secondary input (microphone)
https://forums.stereotool.com/viewtopic.php?t=853
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Author:  Boris [ Tue Mar 23, 2010 12:43 pm ]
Post subject:  Re: Low latency secondary input (microphone)

I put 44100 restart my comp, and now Edcast work without VAC and Repeater..... only Directwire

Author:  hvz [ Tue Mar 23, 2010 8:14 pm ]
Post subject:  Re: Low latency secondary input (microphone)

I finally, finally, finally found out why the performance was different on different systems and depending on whether the display was enabled or not.

In my Intel FFT calls, I accidentally wrote '!=' instead of '==' somewhere... Due to that, no memory was allocated for it in advance, and EVERY SINGLE FFT CALL had to allocate its own memory.

This is fixed now. The performance is now constant (regardless of how Stereo Tool is started), and 6% better than the best performance to date.


I'll post an updated version later tonight. In this updated version, I have also fixed the 'deemphasis does not work correctly in latency < 4096 mode' issue, and if you're using de-emphasis for normal output in latency 4096 mode, the latency is a bit lower.

Author:  Bojcha [ Tue Mar 23, 2010 9:23 pm ]
Post subject:  Re: Low latency secondary input (microphone)

Quote:
I have also fixed the 'deemphasis does not work correctly in latency < 4096 mode' issue, and if you're using de-emphasis for normal output in latency 4096 mode, the latency is a bit lower.
dumb me! .. but what de-emphasis ?

Author:  hvz [ Tue Mar 23, 2010 10:20 pm ]
Post subject:  Re: Low latency secondary input (microphone)

Quote:
dumb me! .. but what de-emphasis ?
If you turn on "normal output" when FM processing is enabled, a lot of processing steps (multiband, final limiter, loudness, singleband compressor, hard limit) are done on a pre-emphasized signal.

If I would just output that you would get very loud highs in the _normal_ output. So, exactly like what would happen in an FM receiver, the sound is de-emphasized there.


Before I hadn't put the deemphasis filter in the latency-optimized chain, it was still causing a lot of extra latency.


Note: Update is building now.

Author:  Bojcha [ Tue Mar 23, 2010 11:20 pm ]
Post subject:  Re: Low latency secondary input (microphone)

ahh :)
ok, de-emphasis will come later for normal output? adjustable ?

Author:  hvz [ Tue Mar 23, 2010 11:31 pm ]
Post subject:  Re: Low latency secondary input (microphone)

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

Note: I just discovered that there's a memory error in FM Calibration (probably also in previous versions). So if you're getting problems, please turn it off... Will check what's wrong later.

Author:  hvz [ Tue Mar 23, 2010 11:31 pm ]
Post subject:  Re: Low latency secondary input (microphone)

Quote:
ahh :)
ok, de-emphasis will come later for normal output? adjustable ?
It has always been there, and always been adjustable. See "Pre-emphasize output" - if that's turned off, the output is NOT pre-emphasized (which in fact means that it's deemphasized, if pre-emphasis is enabled).

The change that I made does make it easier to add what you requested, a mild pre-emphasis (and de-emphasis) to protect MP3s against overshoots.

Author:  hvz [ Wed Mar 24, 2010 1:43 am ]
Post subject:  Re: Low latency secondary input (microphone)

I just noticed that Hard Limit is broken in the last version if Final Limiter or Loudness is used.

Author:  hvz [ Wed Mar 24, 2010 2:30 am ]
Post subject:  Re: Low latency secondary input (microphone)

1. Hard Limit broken for FM output: Fixed (uploaded stand alone and Winamp fixes BETA3, VST not yet uploaded)
2. Hard Limit broken if Loudness or Final Limiter enabled: Still there, but was also present in previous versions. Will check it later.

I've just checked the output against the previous BETA2 version, and the output of this version is identical (except that when de-emphasis is used the latency is a bit lower).

Author:  hvz [ Wed Mar 24, 2010 7:16 pm ]
Post subject:  Re: Low latency secondary input (microphone)

Issue with broken hard limit in certain modes is fixed. (Upload will follow later tonight).

I noticed something that really surprised me, so I'm wondering if others hear the same thing.

I was doing some experiments with the new Bass Boost filter (next to the volume sliders on the main window), and I noticed that I'm actually getting a very good sound with lots of bass if I choose the following settings:

Bass Boost filter
ON: On (duh)
Boost strength: 100%
Maximum boost from 0 upto: 300 Hz (!)
Then dropping to no boost at: 900 Hz (!!!)
Allow harmonics from 0 upto: 900 Hz (!)
Then drop to no harmonics at: 900 Hz
Maximum bass peak level: 150%
Relative to automatically determined peak level: ON
Preserve louder peaks if needed to preserve bass volume: ON

In some cases this results in 'vibrating voices', solution for that is to make the following changes in the Loudness filter settings:
- Deep bass boost: 100%
- Very deep bass distortion protection: Lower (to the right!) the setting to around 70%


Bass Boost does introduce pre-ringing (just like previously Loudness, Multiband etc.) - I'll fix that later.

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