Stereo Tool

I suspect the reason you are seeing slightly different numbers relates to the accuracy of the β values ('modulation' index) being used for the calculations.

For instance, the test frequency required for the first null of the carrier at +- 75 kHz deviation would work out slightly differently depending on which value you used. I have come accross values including 2.4, 2.405, 2.40466 etc.

i.e. If Deviation = β X Test frequency then

Deviation = 2.40466 X 31189.4 Hz = 74999.902604 Hz ?

BBP seems to use a 31187.6 Hz tone for this purpose. I imagine this might be splitting hairs and so maybe for the sake of consistency it might be a good idea to use the same Bessel null frequencies as available in BBP. (Check under Calibration: Test Tone)

Please feel free to point out if I'm totally wrong here...

I know that every single frequency with amplitude 0db makes a deviation of 100% or +-75 khz in the receiver side. Let`s say we put a frequency of 100hz with 0db in the air , we must measure after receiver deviation of +-75khz.
Yeah all of this must be calibrated , so our 0db in the transmitter must equal 0 db in the receiver output.

@DJ-DOGGY we are talking about calibration with spectrum analyzer and bessel null tones.

Stand alone: http://www.stereotool.com/download/ster ... 33-048.exe
Winamp DSP: http://www.stereotool.com/download/dsp_ ... 33-048.exe
VST: http://www.stereotool.com/download/vst_ ... 33-048.dll

Done:
- Sound broken after declipper beep. Big drops.
- Turbo mode on synchronization upon start
- GUI redraw issue
- Mouse placed outside screen during slow dragging

TODO:
- VMware mouse detection based on iteration of identical numbers (x=0, y=different from expected and constant), say 50 times in a row.
- Fixed behavior where clicking on a panel at the bottom could cause sliders to move.
- Improve resampling algorithm and add quality setting
- Move some settings to more logical positions.
- Hide settings such as sound cards in plugin versions

Less urgent for usability:
- Design (several people are working on something)

For later:
- Add 'purpose based' view on settings (for example all settings that affect bass combined).
- Multi-language support
- Add basic/advanced modes
- Add '-6' '-12' etc. beside output bars where possible.
- Context sensitive Help (help button should be next to the preset buttons)
- Drag (resize window parts) lines, also between to/bottom part (scopes/meters).
- Confirm on close (stand alone version)

Stand alone: http://www.stereotool.com/download/ster ... 33-049.exe
Winamp DSP: http://www.stereotool.com/download/dsp_ ... 33-049.exe
VST: http://www.stereotool.com/download/vst_ ... 33-049.dll
Command line: http://www.stereotool.com/download/ster ... 33-049.exe

Done:
- VMware mouse detection based on iteration of identical numbers (x=0, y=different from expected and constant), say 50 times in a row.
- Fixed behavior where clicking on a panel at the bottom could cause sliders to move.
- Improve resampling algorithm and add quality setting

TODO:
- Check report that audio in latest beta is less good than version 6.32. -> Checked, but doesn't seem to be true. Biggest difference is different bass clipping which MAY cause some extra distortion but also gives a warmer more natural sound. If it does cause more IMD, solution would be to slightly lower dynamic bass clipping level.
- I also just found a bug somewhere (turned FM sound card output on and off a few times in the debug version and got an assert - would not be noticeable in the release version - but might still cause issues).
- Fixed a bunch of crashes in the GUI (no idea why they didn't show up earlier...)
- Add FM synchronization offset handling (needed because when the CPU load on different pc's is different the synchronization is not perfect). Best solution: Check diff with previous offset and just insert 0's or remove samples.
- Fix or disable web interface.
- Add warning when someone enabled FM sync.
- Move some settings to more logical positions.
- Hide settings such as sound cards in plugin versions

Less urgent for usability:
- Design (several people are working on something)

For later:
- Add 'purpose based' view on settings (for example all settings that affect bass combined).
- Multi-language support
- Add basic/advanced modes
- Add '-6' '-12' etc. beside output bars where possible.
- Context sensitive Help (help button should be next to the preset buttons)
- Drag (resize window parts) lines, also between to/bottom part (scopes/meters).
- Confirm on close (stand alone version)

I notice that in DSP version the output buffer is full when operate , but in Stand alone the buffer is half filled ?
Why and is this normal ?

And also Normal output in DSP not working , no buffer fill and no sound from there ?

@DJ_DOGGY: Have you enabled FM synchronization?

In the DSP version, if you send 'nothing' to Winamp, Winamp will just keep pushing data into Stereo Tool until Stereo Tool stops processing it. Which happens when the buffer is full - and for jitter I allow the buffer to get twice as big as configured.

Btw - with FM synchronization enabled the buffer will eventually be half-full if you connect to a stream.

Hans, can you explain how the FM synchronization works and how it needs to be set up?

Yeah that would probably be useful.

Say, you have a server that sends out a stream and you want to feed multiple transmitter with that signal. On the transmitter site you open some player (let's say Winamp, because that's easy) to connect to the stream.

Then you have two problems.
- The signals will be out of sync (multiple seconds in many cases)
- Due to minimal differences between sound card frequencies, even if they are in sync at startup they will start to get out of sync over time; in some cases the buffer will fill up until data gets lost because it cannot be played anymore, in other cases the sound card runs slightly too fast and will 'starve' at some point, causing a few seconds of silence before picking up again.

The solution:
- Stereo Tool will keep the buffer filling at a constant position, by slightly increasing or decreasing playback speed. If the buffer filling is identical on multiple systems, the audio will also be in sync (potentially slightly out-of-sync due to OS, CPU load and sound card differences).

Since there will be hiccups and jitter in the reception of audio packets, the synchronization mechanism needs to tune the speed based on long term average delays, and to avoid audible effects it needs to tune with very minimal adjustments. Due to this it can take very very long before signals are in sync, if they start very far out of sync.

To speed up the synchronization at startup there's Turbo mode, in Turbo mode we allow more audible effects to occur. There's also another slider, 'Max adjust', which sets the maximum allowed speed adjustment. By default this is set to 0.5%.

My experience so far is that with the default settings it typically takes about 1-2 hours for streams to get in sync. If you increase 'Max adjust' to 10% it takes about 30 minutes - but you'll clearly hear the effect.

Note that "Send to Winamp" must be set to "Nothing" for synchronization to work. Or you must ditch the output that gets sent to Winamp - if it's sent to a sound card that will automatically lock the FM sound card buffer filling to 50% so no adjustments will be done.


Note: If you use Winamp to play files instead of streams, synchronization will continue to play things faster because data keeps arriving at a too high speed. So only use it for streaming, and ONLY if you really need to synchronize things!

@eldoradofm
Here is more info on the subject:
A Video on Single Frequency Networks http://www.youtube.com/watch?v=q4dJ8S9- ... r_embedded (49 minutes)
A PDF, Technical Overview of Single Frequency Network http://www.enensys.com/resources/suppor ... NENSYS.pdf