Index of /atarilibrary/atari_cd06/UTILITY/AUDIO/M_ANLYZ5

      Name                    Last modified       Size  Description


[DIR] Parent Directory        11-May-2007 21:09      -  
[TXT] FILE_ID.DIZ             07-Aug-1995 13:28     1k  
[TXT] M_ANALYZ.PRG            22-Aug-1995 21:31   117k  
[DIR] SOURCE/                 11-May-2007 21:09      -  

                            Music Analyzer

                          Release 5 (August 1995)


Music Analyzer is a little (well, it was little some time ago) program for the
Atari Falcon. It takes the incoming data from the AD-Converter and uses the DSP
to analyze it. This means that it calculates a 14-band frequency spectrum for
both channels. On the screen you can also see two vu-meters, two oscilloscopes
and a small left vs. right scope.

The program should run on all VGA monitors and RGB monitors and TVs, but on
a VGA monitor it looks much better! (no interlace)

The average screen update frequency is about a little more than 20 Hz. The
speed depends a lot of the input level. The screen update frequency is about
25 Hz when there's no input signal at all. But then there's not much to see
either :-)

In the directory SOURCE you'll find all the (assembler and pascal) sources
necessary to compile the program. (The program itself is written in full
assembly, the little pascal programs are for calculating log tables etc.)
Also included is a small routine written in C which I used to calculate the
FIR-filter coefficients.

The assembler I use is the assembler in the Turbo C package. For the pascal
programs I use Pure Pascal. (Don't think I'm that rich that I can afford
these programs (I'm only a poor physics student), but my father does some
programming too...)

Some people asked me if I couldn't make a GEM version of Music Analyzer. But
I think that this will have the same effect as changing the Falcon clock
frequency from 16 to about 2 MHz. (And even 16 MHz is far too slow for REALLY
nice programs). But if you want to try yourself to make a GEM version, you
can; all source codes are included :-)

Running the program under MultiTOS gives no problems (as far as I know),
it even doesn't run any slower. But you won't be able to switch task.
NVDI and Screenblaster don't give any problems either.

Some history:

Release 1 is the version from 19/7/94 that appeared only in the public domain
serie by 'Stichting ST' in the Netherlands. It was a very limited version
(no mouse control, etc), but maybe therefore also the fastest version :-)

Release 2 is the version from 17/1/95 that had mouse control and didn't have
to be started in TT-medium anymore.

Release 3 is the version from 19/2/95 that had the left vs. right scope added.

Release 4 had no spectacular features added, but it handled video a little
better (the previous versions had some problems with four color modes). It
also had some small (but maybe nasty) bugs removed.

This release (release 5) has some major and a lot of small changes:
- New filter coefficients. When I tested the old coefficients using inverse
  FFT I found out that they hardly worked (I wonder why it still looked this
  good). The new coefficients were calculated with a routine by Frank Vitaljic
  (see FIRCOEF.C) which makes the spectrum analyzer look a lot better!
  The bandpass filter coefficients were calculated by substracting two low-pass
  filters with different numbers of coefficients so the Gauss curve in the
  frequency domain is steeper on the left side than on the right. This because
  of the log division of the frequencies in the spectrum analyzer (no equal
  frequency distances).
- The DSP program doesn't use a single sample buffer (per channel) anymore.
  It now uses 4 continuous buffers per channel for different frequencies. The
  original sample data (32780 Hz) is brought down to a sample frequency of
  8195 Hz using a low-pass filter. Then down to 2048 Hz and finally to a sample
  frequency of 512 Hz. This makes it possible to calculate the lower bands of
  the spectrum analyzer as accurate as the higher ones without using enormous
  numbers of filter coefficients.
- The color palette has been resorted. You won't notice that if you run the
  program, but this way only 1 (one) of the 4 bitplanes has to be changed when
  the scopes are drawn, which increases the speed.
- I changed the boring grey background into a 'grey shaded' surface.
- Grey shaded volume buttons.
- Redrawn help dialog.
- In TV/RGB mode the spectrum analyzer bars are in one color only to stop them
  from flickering (because of the interlaced video).
- Added overflow indicators. I intended to use the Falcon hardware overflow
  detection, but then found out that this can only be used to check for
  clipping at the same moment (that means: not if clipping has occured since
  last checking). To avoid not noticing any clipping I'd have to check for
  overflow 32780 times per second (by CPU).
  Instead the DSP program just checks for every sample data point if it is at
  the upper or lower border (using 16 bit data, so the chance that the data is
  really one of these values is very small).
- You can now set the left vs. right scope in two modes. In the first mode
  (default) the program just draws the data points as single dots. In mode 2
  the data points are connected with (dotted) lines. One problem with this mode
  is that not all data points can be drawn because this would make the program
  much too slow. Another problem is that the high frequencies have to be
  filtered out because else the corners in the lines would be too sharp.

Here's a new FILE_ID.DIZ:

Music Analyzer (release 5, August 95)
for the Atari Falcon. Music Analyzer is
a small (not very usefull) program that
takes the incoming sound from the ADC and
uses the DSP to convert it into graphics,
which means: two scopes, a 2*14-band
spectrum analyzer and a left vs. right
scope. With mouse control (no GEM). All
source codes are included. Written by
Roel van de Kraats (kraats@fys.ruu.nl)


Well, there's not much more to say. I think this is gonna be the final version,
because I don't know what I should add to the program without changing it into
a totally different kind of program. (Maybe you have a suggestion?)
You can use the sources for your own programs if you like (else I wouldn't give
them to you) and you may copy the program and give it to all Falcon owners you
know. Don't forget to give them the sources too!

Oh, and I'm not responsible for any dammage to your computer, stereo-set or
other primary necessities by using this program  :-)

For some more information start the program NOW and press HELP.

That's all,

       ____       ___       ____
       |   \     |   |     |         |
    bFbÿ  |___/ bAbÿ   | bLbÿ |   bCbÿ |__   bObÿ   |  bNbÿ
       |   |     |   |     |         |
       !   |     !___!     !____     !____
           '

For any questions, suggestions or (small) complaints:

Roel van de Kraats
Beekweg 10
3881 LH  Putten
The Netherlands
e-mail: rkraats@dds.nl or kraats@fys.ruu.nl (more reliable)