home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Scene Storm
/
Scene Storm - Volume 1.iso
/
coding
/
c
/
fp_adpcm
/
readme first
< prev
next >
Wrap
Text File
|
1995-08-25
|
2KB
|
93 lines
-----------------------------------
*** Flowerpower's ADPCM package ***
-----------------------------------
This software package is in the public domain.
Do with it whatever you want.
The files in this package will enable you to
* rip CD tracks using a Toshiba Drive and store them in ADPCM format
* play these audio tracks using DeliTracker like ordinary sound modules
* play the files using a stand-alone player, requiring little memory
* convert any known sample format (DataTypes!) to ADPCM format
* an ADPCM datatype is included for use with e.g. MultiView
Why this Program was Created
----------------------------
At a computer meeting in Thanning, Germany, a friend of mine proposed me to
write a program for ripping songs off a CD and saving them as a kind of
"sound module" for use with DeliTracker, taking away as little space as
possible. I used my ADPCM compression routines that I had coded some years
ago. The bet was to code this in 2 and a half hours, but no chance ;-)
Some days later this program was finally finished.
What is ADPCM?
--------------
ADPCM is a lossy sample compression method allowing a very high compression
ratio. The drawback of this compression technique is an audible noise
level, but this is still acceptable.
Example
-------
You can store a 3 minute music track ("Cotton Eye Joe") in 982999 bytes.
This can be further reduced by about 10% using an ordinary packer. You can
listen to this audio track with DeliTracker just like an ordinary sound
module.
Quality Issues
--------------
The samples are stored in MONO.
The quality of ADPCM2 is like a poor tape recording. Ratio 1:4 (25%)
The quality of ADPCM3 is like a good tape recording. Ratio 3:8 (37%)
The Algorithm
-------------
The algorithm is taken from the ZyXel ADPCM compression methods for voice
files and was implemented as a fast assembly routine.
The Sample Format
-----------------
The sample format is highly primitive:
6 Bytes: identifier: "ADPCM2" or "ADPCM3"
4 Bytes: the replay frequency in Hz as ULONG
n Bytes: cruched sample data in ADPCM format
The Author
----------
Christian Buchner
Ganghoferstraße 2
82110 Germering
Germany
Tel.: +49-89-844872
EMAIL: flowerp@eikon.e-technik.tu-muenchen.de
<flowerp> on irc #amiga and #amigager
//
\X/ Flowerpower