Stereo Tool

Bojcha: The AGC behavior has been fixed now (not yet available online).

I have 2 questions:
1. The 44.1 kHz behavior was the correct behavior, at 192 kHz the AGC was responding at only 1/4th of the intended speed. I think you determined your preferred values at 192 kHz? Then I should divide the up and down speeds by 4...
2. How well is the non-FM pre-emphasis doing? When I release a new version (5.03? Or 5.10...) I could immediately add that.


By the way: The Windows Media Player plugin seems to work, but not on all systems - so it's not yet ready to be released...

Hi Hans, you'r back

1. AGC: Put whatever speed you think is ok, yes i made all on 192kHz but no problem for me to recalibrate that.

2. I am not sure what do you think? 25us normal output ?

Ok, clear. I noticed when playing some CD's that at least the up speed was too high, so I think I need to lower at least that.
I've never done any tests with it (with an MP3 encoder attached to it), but you have, so that's why I'm asking if it does indeed help to increase the output level without getting clipping. If it does, I'll add something for this (maybe even a slider so it can be configured precisely )

Ah ok..

Well .. i am still using 25us at stream!
The point of this should be to allow more 'louder' output without clipping and distortiong, especially highs.
But as you know i must use EQ or 'soft limit' to drastically reduce highs!
What is needed is to internaly set EQ (or whatever) to be same spectrum as without pre-emphasized output.
Slider is not good idea. I think that is enough 15 and 25us for normal out and separate internal settings for both modes.

Updated version.

Changes:
- AGC behavior is now identical for all sampling frequencies
- Added 'MP3/AAC spike protection' (pre-emphasis) option in Limiting&Loudness window. Warning: Values are not yet saved; web radio presets still need to be updated.

Bojcha: I read that you have to lower the highs to get the same sound as without the 25us change. I guess there's a bug in that version (which I created very quickly), in this new version that shouldn't be necessary anymore - I've checked that set at 50 us the sound is identical to that of FM pre-emphasis + de-emphasis.

Winamp DSP plugin: http://www.stereotool.com/download/dsp_ ... A510-1.exe
Stand alone version: http://www.stereotool.com/download/ster ... A510-1.exe
VST version: http://www.stereotool.com/download/vst_ ... A510-1.dll
VST version (No SSE2): http://www.stereotool.com/download/vst_ ... A510-1.dll
Command line version: http://www.stereotool.com/download/ster ... A510-1.exe

hmm ..
All seems ok
Well .. i was navigated by that "private version" ...
This is different. All levels are OK and pre-emphasis works as should.
Found 15us as nice position.

It's placed before "Final Limiter" and before "phase rotator" ?
If yes 'maybe' it's better to be after "Loudness" before Hard Limit" or atleast After :Final Limiter"
There more pikes @ Final limiter. So maybe Loudness will better handle that. (?)

Hm... I can imagine that this is a bit confusing. Actually it's placed before Multiband (!); Multiband and everything after that is processed using this pre-emphasis setting. I placed the slider where I had some space left.

yay something new I can play with..

mp3 /wma spike protection cool.


still using the stand along version with virtual l audio cable ( on out put ) and so far so good.
it does have a very small delay to it when you watching TV / you tune. but you get used to it.

It's only useful if you encode your output into a lossy audio format. For listening, it would only (very very slightly) reduce the audio quality...

What MP3 encoder and which settings are you using? I've tried the CoolEdit default MP3 encoder (unfortunately I don't know which one that is) - and for me the spikes start to really disappear between 30 and 40 us. (I'll try some other MP3 encoders to confirm this).

Screen shot (same 30 seconds of sound processed 6 times, before MP3 encoding the peak level is +/- 16383):


Also, while the waveform looks more constant, if I boost it to the same level as the one with spikes the total RMS level is nearly identical - so I'm not really sure how useful this is...