🚀 go-pugleaf

In article <91071.103504SCST86@LIVERPOOL.AC.UK> SCST86@LIVERPOOL.AC.UK writes:
>Hi There,
>I'm experimenting with sample compaction and decompation. I've
>developed an  algorithm of my own but the quality it gives is not very
>good (pretty aweful    actually B-))
>
>I was wondering if anyone in
>NetLand had any articles or advice that they   could mail me.
>
>I'm
>dealing with 8 bit samples at any rate you care to mention. The idea is
>that I take data from a slow stream (like a floppy) and play it back in
>real time.
>
>Thanks in advance.
>
>Mail to.....
>Jason Timmins                My Card.... +-------------------------+
>Dept. Of Computer Science,               |                         |
>University Of Liverpool.                 |      Jason Timmins      |
>JANET: SCST86@UK.AC.LIV.IBM              |  (I can waggle my ears) |
>   OR: SCST86@UK.AC.LIV.UXA              |                         |
> TELE: (UK) 0860 600 758                 +-------------------------+

  I don't know whether this would help or not, but there are several
programs on the Amiga that play back samples in real time from floppy
up to speeds of about 14khz. Any faster and it starts falling behind while
the floppy catches up. On the Amiga, sound samples are encoded in the
standard IFF FORM 8SVX using fibonacci delta compression. I think this
method compresses samples by 50% by encoding 8 bit samples as 4 bit
changes from the last sample. The way the player program works is by
double or quadruple buffering samples read from the disk. The Amiga's
Audio and Disk are driven by DMA, so you can load and play sounds
with little processor intervention. The major overhead is the seek delays
on the disk. Try ftping from abcfd20.larc.nasa.gov in directory
/incoming/amiga. Look file a file called 'AGMSPlaysound'. It contains
C source code for the player. You may find some help on encoding methods
and buffering techniques in the source.

Hope it helps...

BTW, I know the techniques use in the source work. I've used it to play
an entire disk long sample of the theme to 2001, and a long sample of
Madonna's VOGUE. (about 45 seconds worth.)