Stereo Tool

yes, right
i have forgotten for rds section.

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control point2

Hi Hans,
I have tried to listen to various type of music using the new beta dsp version 3.54 at 50 us, I found the sound is a bit warmer than the ver.3.53 with better base. Moreover, the sound is still loud, clean and free of distortion as what we've seen in ver.3.53, but I still feel there is some trace of annoying high frequency; this makes me feel that the frequency response is still not as flat as ver.3.40. Please note that I cannot use my judgment by listening to sound at 75 us, as all my listening test is done using receivers meant for 50 us.
I really like the new look of stereo tool window, well done with the output graphs, it looks more professional with all the required tools and displays…Super!!!. The CPU Usage checked in my Intel-Pentium Dual-Core Processor 2.16 GHz Notebook is around 30%-40% for the beta ver.3.54 with the graphs, while it is around 20%-30% for ver.3.53.
I wish Hans if you could possibly try to replace the fixed frequency equalizer with a parametric equalizer so that the user has the option to adjust more selective frequencies to suite his taste.
The above was a quick listening test, I would be glad to give more comments when I do more comparison using variety of music.
Thank you and regards,
Abdul

Hi Abdulok,

The annoying highs are caused by the Loudness filter, not so much by the equalizer settings (that is, if we are talking about the same thing). Set "Loudness" to a lower value (below 2) and they should be gone.

I'm assuming you're listening at the FM Loud or Extreme preset, here the Loudness value is set to 3 or 4, where in version 3.40 it was set to 2.3 at most.

Here's what's happening: For 16 bit audio, sample values can be between -32768 and +32767. If I have a loud S sound which peaks up to 20000, and a bass that peaks at 10000, they can be combined perfectly within the range. But, if I set Loudness to 4.0, the values are multiplied by 4 - so the bass peaks at 40000 (doesn't fit) and the highs peak at a whopping 80000. Combined they would peak at 120000.

The Loudness filter then performs a lot of neat tricks to squeeze the sound back into the -32768..32767 range. This is not always possible, and if it's not, some or all of the sounds are made softer. What goes wrong here is that the high frequency sound which is extremely loud will push down the rest of the sound - often in short spikes - so much that it becomes annoying.

What I've done now is I've added an extra filter between the final limiter and the Loudness filter that reduces loud high frequencies. The thing is, if I reduce them too much the sound will lack highs. Too little means that the annoying effects are still present, and the bass/mid level (warmth) is reduced.

About the CPU usage: That's way too much. I think I have an idea to greatly reduce it, will look into it.

About the parametric eq: I could do that, BUT the current clippers in the multiband filter assume (and have to assume) that every band is exactly one octave. That's also the reason that there are 10 bands.... So for now it's not possible

Small update: The improved processing should now also work properly for 50 us. (FM Europe presets). Only if Loudness > 2.2 (High quality) or 3.0 (Normal quality).

And another small update: CPU load when the new wave/mpx displays are on should be a lot lower now.

tested standalone,

- in basic mode one new graph is on stange position. (shuld not be visible in basic mode?)
- when i turn on pre-emphasize, new output graph stops.
- new graphs working better now.

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control point
control point2

Hi Hans,
You are right about the effect of the loudness on the frequency response; yes I have managed to get the natural sound of what we used to get from ver.3.40 in this beta ver.3.54 by slightly reducing the loudness value. It seems also that the sound is improved with the latest update. I must admit that the sound of stereo tool is clean and it is much much louder than any of our local FM stations. I have also checked the CPU usage, it is seems to be lower now, fluctuating between 25% and 35%.
I have noticed a strange thing happening whenever I switch to main window and select one of the presets i.e. "FM Tx (Europe,Stereo)" and when I attempt to check the equalizer check box, I see the values of Multiband Compressor and its associated up speed, down speed and clipper all get changed, this can only happen after you first attempt to select a presets.
Thanks and kind regards,
Abdul

True

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control point
control point2

I know - this is a rounding error. (eg. the preset sets a value to 0.00004, then the slider position is read back as 0.0000399999 and that gets rounded off to 0.00003). This problem has actually been there since version 2.0 or so but I'll see if I can fix that in a later version.

Another small update:

1. Oops - solved
2. Solved - but sometimes the de-emphasized graph is shown. Will fix that later (probably tomorrow).
- The MPX spectrogram is now turned off when no high frequency FM output is generated.
- Performance of displaying bars and graphs should be slightly better (although I couldn't measure any difference - but it might be better on some systems).
- I have slightly increased the maximum high frequency sounds level for high Loudness values. In a future version (when I have the new interface with separate windows) I'll make it configurable (and probably some other Loudness settings as well) - but right now I just don't have any space to put it. (And on top of that, if I add it all to the current already crowded window it will only make things more difficult).

Remaining bugs:
- Sometimes de-emphasized output graph is shown instead of pre-emphasized graph.
- Sometimes both the output graph and the output volume display are shifted in time w.r.t. the input displays.

THERE IS NO CHANGE IN THE SOUND PROCESSING IN THIS VERSION.