USRobotics -> .au (.wav, etc.)

• Messages sorted by:[ date ][ thread ][ subject ][ author ]

Just wanna let everyone interested know that using info from 
http://149.112.36.201:28800/ae-pcd/index.htm
I was able to write a couple lines converter from
USRobotics Sportsters voice files to .au files.
All I did - stripped header and frames and used mentioned "untoast" to
decompress the file. It works !

http://149.112.36.201:28800/ae-pcd/voiceprogram.htm:
...
The modem will begin presenting GSM encoded voice data across the serial
port. The format
of the data is in 38 byte frames as follows: 

0xB6 0xB6 [1 ..{GSM FRAME}.. 34] 0xA5 0xA5
0xFE 0xFE [1 ..{GSM FRAME}.. 34] 0xA5 0xA5

Frames beginning with 0xB6B6 denote a GSM frame that constitutes voice
data that is below
an arbitrary silence threshold set by the DSP. 0xB6B6 is only a marker
for what the modem
considers silence. Frames that begin with 0xB6B6 still contain valid GSM
encoded voice data
and may be played back using either the 0xB6B6 or 0xFEFE frame header. 

These frame headers and footers should be kept if only the modem is
being used for record
and playback. They should be stripped if GSM decoding is to take place
by a process in the
DTE. 

The 34th byte of GSM frame data is always 0 and is LSB resulting in a
standard 33 byte GSM
data format. 
...