Dagy

29th July 2002 23:08 UTC

Beat detection from linein://
Hi,

We are using avs on parties as a VJ software, we like
the tons of good presets, good framerate and other avs stuff, but beat detection from line-in is very poor.

Can anyone help ?

UnConeD

30th July 2002 07:53 UTC

Turn off advanced beat detection because it will think the linein:// is only one song and never re-adapt the BPM when needed.

Dagy

30th July 2002 09:28 UTC

Yes, but
Yes, but ( of course with respect to NullSoft developers )
may be the bpm decetion needs little bit downgrade, from
sophysticated detection algorithms to at first try
detect bpm simply from level of signal. In many cases this
is the right value and is available with second beat comming.

Of course I don't know detailed problems inside buffers and other
stuff, may be it is complicated to compute medium value of signal level in some time period , may be not...

UnConeD

30th July 2002 10:01 UTC

Well actually this *is* what standard detection does.

I don't think you realise just how advanced the human ear and brain are for sound-processing though. Songs that we perceive to have a clear beat or rhythm that 'should be easy to detect' can still be very homogenous in terms of signal strength. In fact the only kind of 'music' where this approach works well is your basic boom-boom-boom-boom-boom techno. Anything more complicated is hard to do.

Remember that our ear has an incredibly advanced and accurate processing tool: the Cochlea (spiral-shape) which does a natural splitting of a sound into its frequency components, combined with our brain: an advanced neural network that has been trained for years.

I read a great example of this a while ago, where a mathematician had a certain problem that was hard to solve numerically because he wanted to isolate a small fraction of a signal or series of values. However when he converted the obtained values/signal into sound, he could easily locate the correct solution by listening carefully.

If you don't believe me you should study the little spectrum in Winamp or AVS and see if you can give me a clear description of what a beat's sound looks like on there :).

Rovastar

30th July 2002 10:30 UTC

Goto Jaspers here http://home.hccnet.nl/th.v.d.gronde/

and download the input and output plugins. This are a must for all live VJ sets.

The low latency output is probably the most important for live sets.

AS winamp Gets input THEN outputs (of which there is a large (for live set standards) buffer) THEN uses the visual plug-in.

This will improve the beat detection and reduced the latency a bit.

It is immpossible for any computer in the world to detect a beat the best we can do is guess.

Dagy

30th July 2002 18:32 UTC

Jaspers
I've tryed linein from jaspers but it has big latency
about 1 second.

Is it new version out there ?

Rovastar

31st July 2002 10:06 UTC

You can configure the buffer size etc to get the best size for you should not be 1 second.:confused:

But as I said the most important one is the output plug-in being the low latency one. That will save you about a tenth of a second. You can use the normal Nullsoft linein with this if you are having problems.