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 Post subject: Re: Re-Broadcast Stream
PostPosted: Tue Apr 22, 2008 10:11 pm 
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Joined: Mon Mar 17, 2008 1:40 am
Posts: 9764
Couple quick questions -- what types of digital filter implementations are used in Stereo Tool (IIR Bandpass? What order? Are they phase linear, etc)? Also, how does the "loudness" control work internally? Of course if the answers are secret, I understand :)

Hi Hellmanc!

The digital filtering is done mostly using Fourier transforms (FFTs actually). That's the basis of the Stereo, Dualband and Multiband filters.

The Loudness filter is something that I haven't seen elsewhere so far, and it took me a few weeks to tweak it to sound ok, so I'ld like to keep that one secret for now ;)

 Post subject: Re: Re-Broadcast Stream
PostPosted: Tue Apr 22, 2008 10:48 pm 
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I first started using 2.10 a year ago and liked how clean it sounded, however the old version didn't level the volume as well or allow (direct) equalization. This new version has good volume levelling (with pre-limiter), equalization and much more! IMO -- the less aggressive settings sound the best. Of course, broadcast audio processing is all about trade-offs between loudness and other aspects of perceived quality.

Great Job with this program!
About the less aggressive settings: I have just uploaded a new version (3.03) with this simpler interface described above, I've also added a bugfix and (not in the beta mentioned in this thread): I have made most of the compression settings a bit less aggressive. (Actually, I have even made the "Very soft compression" setting less aggressive...)

 Post subject: Re: Re-Broadcast Stream
PostPosted: Sun May 04, 2008 11:21 pm 
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The "chipmunk" sounds have been completely removed in the new 3.10 beta version, which can be downloaded at

Other changes:
- Improved FM transmitter support
- Multiple output channels (eg. 1 for FM transmissions and 1 for streaming)
- RDS support: Added PI, PTY, RadioText, ClockTime, M/S, TA, TP, Stereo, Compression, Artificial Head.

The reason it's a beta release is that I'm not so certain that the FM transmitter support will work well on all systems (I think that it does, but I'm waiting to get some responses on the new version first).

 Post subject: Re: Re-Broadcast Stream
PostPosted: Mon May 05, 2008 11:57 am 

Joined: Wed Apr 16, 2008 6:21 am
Posts: 45
Thanks for the new version with it's fixes and additions :)

It' sounds good and I think the presets reflect that.

It might be awhile before you get some feedback on the FM part.
I doubt seriously that many have 192khz capabilities.

 Post subject: Re: Re-Broadcast Stream
PostPosted: Mon May 05, 2008 12:24 pm 
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Well, some people are already using it (and it's working there), I've also tested it on a lot of PCs by now, so I'm getting confident that I can release it.

I'm also going to add a bug fix: I noticed that in some cases the sound is very "shrill" instead of warm. Found the cause of that, will probably have a fix by tonight.

 Post subject: Re: Re-Broadcast Stream
PostPosted: Tue May 06, 2008 1:31 am 
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I have just uploaded a new beta with slightly improved sound quality. Certain types of sounds (lots of bass, little highs) could sound very shrill when the Pre Amp was set to a very high (20+) value. This is now reduced a bit.

 Post subject: Re: Re-Broadcast Stream
PostPosted: Tue May 06, 2008 6:52 pm 

Joined: Tue Apr 22, 2008 5:40 pm
Posts: 6
I've noticed that with alot of these types of plugins, the high frequencies can become shrill, possibly due to overenhancement and also possibly due to MP3 artifacts (if MP3s are used as an input source). I've noticed that if you reduce the high band too much, you lose 'clarity' / 'brightness', etc. One trick that I have had luck with, is to keep the high band boosted, but to apply a very fast limiter after the compression on the high band, to keep the high band in check. It could make for more consistent highs -- it will boost up the dull material nicely, and will keep the highs in check with material that already has extreme / loud highs. If this technique is overdone, it can smear the high frequencies (like high hats, etc).

 Post subject: Re: Re-Broadcast Stream
PostPosted: Wed May 07, 2008 12:20 am 
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I've noticed something similar - but doing so didn't solve it in all cases. Eventually I have now linked the pre-limiter high band to the low band: If the high band is amplified more than the low band, I'm using the average of the low and high amplification for the high band. Also, it helps to keep the Pre Amp slider lower (for Pre Amp values of 10 and lower, this effect did not occur at all - and especially at very high values, > 20, it became annoying). With the fix slightly higher Pre Amp values will still sound good.

 Post subject: Re: Re-Broadcast Stream
PostPosted: Fri May 09, 2008 8:57 am 

Joined: Tue Apr 29, 2008 8:32 am
Posts: 25
Location: Rogers AR
This high end shrillness from low bitrate mp3's is what i have been fighting for years. The agc setup in sound solution, many other plugins, and sam ver3+ have not allowed me to address this. I think I finally have an answer. look at it and maybe you can add a stage in front of the preamp. i am finally happy with the sound but will work to replace lowbitrate mp3 with 320k ones. even then different music styles and different recording labels make me want to change settings for each.

i will post my settings if i can. What i have done after several days of twiking/expermenting and listing to many hundreds of songs over air with several radios is this.

remember i use SAM 4 so I turned on the 5 band stage in sam-mixer-agc. everything is off but the 5 band and then only the expander and limiter , not the compressor. And only for the 3 top bands #'s 3, 4, and 5. band gain sliders should all be 0.

the problem is with different songs using the preamp and prelimiter as a form of AGC boost the artifacts created by the mp3 compression. any setting over about 2.18 on the slider will cause crackling and shrillness especally on the s and sh sounds. the agc in other dsp all suffered from the same issue.

using this setup gets me 3 things.
1) a very nice 3 band limiter on the high end only. this can be set to drop the edge off the highs and reduce the tininess.
2) an expander to bring out the quite between notes, a little more help for the quiter passages
3) band link sliders. linking 4 and 5 about 6% really helps drop the essss off.

this has allowed me to push the preamp slider in STool back up a bit and ease the compression in the multiband. this lets me bring up the highs and open up the sound. lower bitrate mp3 96k now sound much more like a 320k. not as rich since to much data is lost in the encode but at least the annoying tinness(sic) and esss is droppedway down with out dulling the sound.

maybe you can add a multiband stage before the preamp for highs only. if i can post my preset from sam i will. sts extensions still not allowed so here is my current on air preset.


Stereotool preset

Pre amplifier=3.139999866
Post amplifier=1
Extra loudness=1.090000033
Hard limit output=1
Downsample very high input sample rates to near 44.1 kHz=0
[Singleband Compressor]
Maximum volume=1.5
Maximum value=24576
Attack speed=0.00009
Decay speed=0.100000001
Above Top Limiter=0
[Pre Compressor]
Delay enabled=0
Maximum volume - Band 1=27970
Maximum volume - Band 2=10170
Attack speed - Band 1=0.000032212
Attack speed - Band 2=0.000032212
Decay speed - Band 1=0.001414664
Decay speed - Band 2=0.002081846
[Multiband Compressor]
Delay enabled=0
Very high quality enabled=1
Maximum volume - Band -1=5250
Maximum volume - Band 0=7120
Maximum volume - Band 1=7120
Maximum volume - Band 2=6940
Maximum volume - Band 3=6850
Maximum volume - Band 4=6610
Maximum volume - Band 5=5420
Maximum volume - Band 6=4410
Maximum volume - Band 7=3220
Maximum volume - Band 8=850
Attack speeds linked=0
Attack speed - Band -1=0.000090152
Attack speed - Band 0=0.000264443
Attack speed - Band 1=0.000264443
Attack speed - Band 2=0.000090152
Attack speed - Band 3=0.000072158
Attack speed - Band 4=0.000072158
Attack speed - Band 5=0.000055309
Attack speed - Band 6=0.000055309
Attack speed - Band 7=0.000034489
Attack speed - Band 8=0.000055309
Decay speeds linked=0
Decay speed - Band -1=0.001414664
Decay speed - Band 0=0.001828427
Decay speed - Band 1=0.00160793
Decay speed - Band 2=0.0010933
Decay speed - Band 3=0.0010933
Decay speed - Band 4=0.0010933
Decay speed - Band 5=0.0010933
Decay speed - Band 6=0.001244719
Decay speed - Band 7=0.001244719
Decay speed - Band 8=0.001244719
Above Top Limiter=0.699999988
Clipping enabled=1
Postprocessing enabled=1
Relative clip position - Band -1=1.777777672
Relative clip position - Band 0=1.985074759
Relative clip position - Band 1=1.985074759
Relative clip position - Band 2=1.985074759
Relative clip position - Band 3=1.985074759
Relative clip position - Band 4=1.985074759
Relative clip position - Band 5=1.985074759
Relative clip position - Band 6=1.985074759
Relative clip position - Band 7=1.985074759
Relative clip position - Band 8=1.985074759
Final limiter value=0.354799986
Final limiter decay speed=0.002506041
Final limiter clipping=1.56410265
Equalizer enabled=1
Equalize before multiband-compression=0
Equalizer position - Band -1=0.886792541
Equalizer position - Band 0=1.247190952
Equalizer position - Band 1=1.247190952
Equalizer position - Band 2=0.886792541
Equalizer position - Band 3=1
Equalizer position - Band 4=1.127659559
Equalizer position - Band 5=1.247190952
Equalizer position - Band 6=1.127659559
Equalizer position - Band 7=1
Equalizer position - Band 8=0.886792541
Delay enabled=0
Center bass=1
AZIMUTH limit=12.199999809
AZIMUTH change speed=1.370000005
Image phase amplifier=1.330000043
Image phase amplifier maximum angle=180
Image phase amplifier maximum separation strength=25.63999939
Image width amplifier=1.110000014
Extra phase shift=0
Mono or stereo only=0
[Channel Delay]
Left Delay=0
[Output Filter]
Lowpass filter=15000
[Final Pre-Limiter]
Response time=0.400000006
[Final Limiter]
Response time=0.100000001
[FM Transmitter]
Pre-emphasis time=50
Output is pre-emphasized=0
Stereo encoder enabled=0
RDS encoder enabled=0
RDS PS text=2s:STEREO/2s:TOOL/<1=1.5s,2..-2=2t,-1=1.5s:WWW.STEREOTOOL.COM

here is my sam 4 agc setting

<CONFIG application="SAM" version="4.3.6"><AGC><Enabled>-1</Enabled><GatedAGC><Enabled>0</Enabled><GateLevel>-25</GateLevel><MaxGain>0</MaxGain></GatedAGC><StereoExpander><Enabled>0</Enabled><Depth>8</Depth><Level>40</Level><Threshold>-21</Threshold></StereoExpander><BassEQ><Enabled>0</Enabled><Freq>72</Freq><Gain>3</Gain><BassEqType>1</BassEqType></BassEQ><PreEmphasis><Enabled>0</Enabled><PreEmpType>1</PreEmpType></PreEmphasis><MultiBand><Enabled>-1</Enabled><Link01>0</Link01><Link23>6</Link23><Link34>10</Link34><Drive>0</Drive><Gain0>0</Gain0><Gain1>0</Gain1><Gain2>0</Gain2><Gain3>0</Gain3><Gain4>0</Gain4><Bands><MBand0Proc0><Enabled>0</Enabled><Ratio>3</Ratio><Threshold>-16.7000007629395</Threshold><Attack>180</Attack><Attack2>138</Attack2><Release>65</Release><Release2>500</Release2><Hold>44</Hold></MBand0Proc0><MBand1Proc0><Enabled>0</Enabled><Ratio>2.59999990463257</Ratio><Threshold>-10</Threshold><Attack>214</Attack><Attack2>500</Attack2><Release>65</Release><Release2>2000</Release2><Hold>44</Hold></MBand1Proc0><MBand2Proc0><Enabled>0</Enabled><Ratio>2.59999990463257</Ratio><Threshold>-12.5</Threshold><Attack>167</Attack><Attack2>500</Attack2><Release>176</Release><Release2>2000</Release2><Hold>37</Hold></MBand2Proc0><MBand3Proc0><Enabled>0</Enabled><Ratio>2.5</Ratio><Threshold>-15.8000001907349</Threshold><Attack>221</Attack><Attack2>500</Attack2><Release>398</Release><Release2>2000</Release2><Hold>64</Hold></MBand3Proc0><MBand4Proc0><Enabled>0</Enabled><Ratio>2.5</Ratio><Threshold>-17.5</Threshold><Attack>180</Attack><Attack2>500</Attack2><Release>398</Release><Release2>2000</Release2><Hold>64</Hold></MBand4Proc0><MBand0Proc1><Enabled>0</Enabled><Ratio>2</Ratio><Threshold>-25</Threshold><Attack>10</Attack><Attack2>0</Attack2><Release>10</Release><Release2>0</Release2><Hold>24</Hold></MBand0Proc1><MBand1Proc1><Enabled>0</Enabled><Ratio>2</Ratio><Threshold>-24.2000007629395</Threshold><Attack>10</Attack><Attack2>0</Attack2><Release>10</Release><Release2>0</Release2><Hold>24</Hold></MBand1Proc1><MBand2Proc1><Enabled>1</Enabled><Ratio>2</Ratio><Threshold>-25.7999992370605</Threshold><Attack>10</Attack><Attack2>0</Attack2><Release>10</Release><Release2>0</Release2><Hold>24</Hold></MBand2Proc1><MBand3Proc1><Enabled>1</Enabled><Ratio>2</Ratio><Threshold>-25</Threshold><Attack>30</Attack><Attack2>0</Attack2><Release>121</Release><Release2>0</Release2><Hold>24</Hold></MBand3Proc1><MBand4Proc1><Enabled>1</Enabled><Ratio>2</Ratio><Threshold>-25.7999992370605</Threshold><Attack>37</Attack><Attack2>0</Attack2><Release>121</Release><Release2>0</Release2><Hold>24</Hold></MBand4Proc1><MBand0Proc2><Enabled>0</Enabled><Ratio>0</Ratio><Threshold>-14.1999998092651</Threshold><Attack>64</Attack><Attack2>0</Attack2><Release>65</Release><Release2>0</Release2><Hold>17</Hold></MBand0Proc2><MBand1Proc2><Enabled>0</Enabled><Ratio>0</Ratio><Threshold>-8.30000019073486</Threshold><Attack>112</Attack><Attack2>0</Attack2><Release>65</Release><Release2>0</Release2><Hold>17</Hold></MBand1Proc2><MBand2Proc2><Enabled>1</Enabled><Ratio>0</Ratio><Threshold>-16.7000007629395</Threshold><Attack>85</Attack><Attack2>0</Attack2><Release>121</Release><Release2>0</Release2><Hold>30</Hold></MBand2Proc2><MBand3Proc2><Enabled>1</Enabled><Ratio>0</Ratio><Threshold>-18.2999992370605</Threshold><Attack>85</Attack><Attack2>0</Attack2><Release>342</Release><Release2>0</Release2><Hold>64</Hold></MBand3Proc2><MBand4Proc2><Enabled>1</Enabled><Ratio>0</Ratio><Threshold>-20.7999992370605</Threshold><Attack>112</Attack><Attack2>0</Attack2><Release>232</Release><Release2>0</Release2><Hold>64</Hold></MBand4Proc2></Bands></MultiBand><DualBand><Enabled>0</Enabled><Drive>0</Drive><Bands><MBand0Proc0><Enabled>0</Enabled><Ratio>2</Ratio><Threshold>-20</Threshold><Attack>105</Attack><Attack2>425</Attack2><Release>65</Release><Release2>2000</Release2><Hold>24</Hold></MBand0Proc0><MBand1Proc0><Enabled>0</Enabled><Ratio>2</Ratio><Threshold>-10</Threshold><Attack>105</Attack><Attack2>500</Attack2><Release>65</Release><Release2>2000</Release2><Hold>24</Hold></MBand1Proc0><MBand0Proc1><Enabled>0</Enabled><Ratio>2.5</Ratio><Threshold>-19.2000007629395</Threshold><Attack>44</Attack><Attack2>0</Attack2><Release>65</Release><Release2>0</Release2><Hold>12</Hold></MBand0Proc1><MBand1Proc1><Enabled>0</Enabled><Ratio>2.5</Ratio><Threshold>-19.2000007629395</Threshold><Attack>51</Attack><Attack2>0</Attack2><Release>65</Release><Release2>0</Release2><Hold>12</Hold></MBand1Proc1><MBand0Proc2><Enabled>1</Enabled><Ratio>0</Ratio><Threshold>-18.2999992370605</Threshold><Attack>85</Attack><Attack2>0</Attack2><Release>232</Release><Release2>0</Release2><Hold>58</Hold></MBand0Proc2><MBand1Proc2><Enabled>0</Enabled><Ratio>0</Ratio><Threshold>-7.5</Threshold><Attack>105</Attack><Attack2>0</Attack2><Release>342</Release><Release2>0</Release2><Hold>51</Hold></MBand1Proc2></Bands></DualBand><Clipper><Enabled>0</Enabled><Level>0.100000001490116</Level></Clipper><OutputLevel><OutputLevel>100</OutputLevel></OutputLevel></AGC></CONFIG>

 Post subject: Re: Re-Broadcast Stream
PostPosted: Sun May 11, 2008 2:41 am 
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Joined: Mon Mar 17, 2008 1:40 am
Posts: 9764
khel973: I'll have to look into this... The type of shrillness that you are talking about is not the same that hellmanc and I were talking about - but it could also be very useful to be able to fix bad MP3s.

I'm currently working on a noise gate. I always thought that those would ruin the sound - but as it turns out, the result sounds much clearer than without it, and even brand new tracks (recorded this year) benefit from it. I hope to get it ready by tomorrow. I'm really curious about its effect on bad quality MP3s... At least for good quality recordings with some background noise it brings a major sound quality improvement.

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