Stereo Tool

Hi Bojcha,

The singleband compressor currently does NOT use the RMS volume. It doesn't work that badly, but it must be possible to let it work much better.

I've now (not yet uploaded!) added an RMS calculation step, so for each portion of sound I know the RMS volume. What remains is reducing the volume at spikes, such that I eventually reach the wanted (constant) RMS volume. It's a bit more difficult than I had expected (and hoped), but it should be possible.

My first attempt was to use the peak level and the RMS volume, which worked remarkably well - except that for some sounds (basically female voices / trumpet / strings like sounds) the peak level is very high because the signal is not symmetrical. And then the RMS/peak factor is too low (RMS volume compared to peak level seems to be very low), which in turn leads to a much higher output level So 95% of the sounds are within a 1 dB range (even if I compare your very badly mixed song with 1980s tracks which have almost no compression, which is pretty good), but some are a few dB louder, which is far too much.

I hope to get something working tomorrow...

heh .. exactly i get when i turn on Singleband Limiter/comrpessor..
Things are better .. but voices have higher RMS power ..

Strange... I would have expected the opposite there

Anyway, I have a method to measure the RMS volume, so I can control the output volume to follow it. So it should be possible to make the volume very constant.

Here is current preset i set for FM with singleband compressor/limiter...

little pumped ?

Edit:
After day of listen i realized that this preset with this SingleBand comrpessor/limiter is wrong. Preset is good without it.
This sometimes "level Down" seems is because Final Limiter, like Limiter is working by RMS and peek combined but more by RMS.
Let's see what will Hans do with single compressor/limiter and PreLimiter.

I have something RMS-based that seems to work ok. But only if the response (volume up/down) is set very slowly (compared to the defaults in the old pre limiter). If you set the speed much faster, the volume starts to drop BEFORE a loud sound kicks in, which is very annoying (the same thing happens if you do set it very slowly, but then it's not noticeable.)

Also, for the female voice that reduces other sounds too much: I noticed that lowering "Pre Amp" to values below 10 (around 6) greatly reduces it. So that's probably (at least part of) the solution. (I can probably improve - but not completely fix - this a bit later).

New version will be posted in about an hour.


Note: The 'singleband' filter is broken again in this version - if you turn it on you'll only hear silence!
Note 2: To configure the response speed and output volume of the new RMS-based pre limiter, only use the sliders of the first band - the sliders for the 2nd band are ignored. And the output bars don't show anything useful.
Note 3: Keep Pre Limiter 'remove remaining peaks' off, or you'll get distortion. Will look into that later.

For some reason the build was hanging. I've just restarted it, so it will take another hour from now.

Updated pre limiter available, as BETA3 again.

As mentioned earlier, keep the up/down speeds low (the default values should be fine). And make sure that "Remove remaining peaks" is off (also, don't turn the singleband compressor/limiter on, or you'll only hear silence).

Please let me know how well this works.


Changes w.r.t. the original Pre Limiter:
- It's now a single band
- For each block of sound, it measures the RMS volume and calculates the 'wanted' volume. (If I would just use that, the output volume would be constant +/- 0.1 dB). If the 'wanted' volume is lower, the volume is dropped. If the difference is small, there's almost no drop, if it's really big, the 'wanted' volume is reached in just a few steps.

Note that the new volume is used on the entire block, which means that volume drops can start BEFORE a loud spike occurs. I'm going to try to fix that later. With low 'up speed'/'down delay' values, this shouldn't be an issue.

When I disable the multiband compressor by unchecking 'ON' in the multiband compressor window, the sound stutters and is all weird.

Here's a recording:
Example (mp3, 240 kB)

At 0:10 second I turned off the multiband compressor.

@Kakoon
Here is all ok !? no stuttering.

@Hans
Seems that definitely is better Singleband PreLimiter. BUT! Multiband need to be re-tweaked
New RMS Prelimiter.. sounds now like he's now knows what is doing.

In the same time i was thinking about bass sounds and i tweaked them always from EQ (after multiband) but that was wrong.
The output level like this is only BASS based so Limiter after that will mostly limit by bass sounds.
And when is "before multiband" things are better for limiter, but there is no bass sounds that much when was with EQ after multiband.
So when i look at eg. Omnia processing they have something like Bass boost or deep bass enhance (bass compressor limiter or whatever) between AGC and multiband, so i gues like that they preserve peek level of bass sounds but again is boosted.
i Have new preset now for latest beta, it's "constant" but i don't like the fact i must push bass EQ to +5 to +7dB.

I tried your preset, and indeed no stuttering when disabling the multiband compressor.

But try this preset:
stutter.sts

Turn off the stereo enhancer and you even only have a hissing sound...