1. !/usr/bin/perl
2. ------------------------------------------------------------------------------
3. Create ringtone file for Grandstream BT100 phone, using uLaw input.
5. Author: Tony Mountifield <tony@softins.co.uk>
6. Date: 28 May 2004
7. File: makering.pl
8. History:
9. 28/05/2004 Initial version.
10. 29/05/2004 Added checks for input file size being even and not too large.
11. 30/05/2004 Phone will not accept files larger than 65536 bytes.
12. 06/06/2004 Modified for the 1.05.00 firmware, probably doesn't support
13. older firmware any longer
14. ------------------------------------------------------------------------------
16. Usage:
17. Use sox to convert any audio input file to uLaw and pipe to this prog, e.g.
19. sox inputfile -r 8000 -c 1 -t ul - rate | makering.pl ring1.bin
21. (try using /usr/share/sounds/phone.wav for the inputfile)
23. Check the output file by using the following command:
25. tail +513c ring1.bin | play -t ul -
27. Finally, put the ring file in /tftpboot on the phone's TFTP server,
28. and reboot the phone.
30. ------------------------------------------------------------------------------
32. Credits:
33. Based on analysis by Stephen R. Besch <sbesch@acsu.buffalo.edu>
35. Copyright: placed into the public domain by the author
37. Warranty: none!
39. ------------------------------------------------------------------------------

$filename = shift or die "need output filename\n";

undef $/; # slurp whole file at once...

$audio = <>; # ... like this

$filesize = 512 + length $audio;

if ($filesize & 1) {

1. length odd, add a zero byte (should never happen)

$audio .= chr(0);
}


if ($filesize >= (2 * 65536)) {
print STDERR "Warning: $filesize is bigger than 2 bytes, trouble may be ahead."
}

1. this is the format for the header

$headerfmt = "N n C4 n C C C C a16 C C x4 n n x214 n n N x72 a176";

1. get the current date and time

($min, $hour, $day, $month, $year) = (localtime)[1..5];
$year += 1900;
$month += 1;

1. create the header, with zero for the checksum

$header = pack $headerfmt,
$filesize/2, # 00 - filesize/2

1. FIXME: I'm guessing that the 0000 we
2. always see at the beginning of
3. the files are an extended file size

0, # 04 - put checksum in later
1,0,0,1, # 06 - version
$year, # 0a - year
$month, # 0c - month
$day, # 0d - day
$hour, # 0e - hour
$min, # 0f - min
"ring.bin", # 10 - name, seems to always be ring.bin

1. FIXME: Assumption 1: always ring.bin
2. FIXME: Assumption 2: name field is 16 chars

0, # 20 - ?
0, # 21 - ? 0 (ring1.bin) or 9 (ring2.bin) - Codec?

1. 22 - 4 NULL bytes, unknown

0xc8, # 26 - ? 00C8 (0 sometimes seen before)
0, # 28 - 0000 (ring2.bin) or 0001 (ring1.bin) - why?

1. 2a - 214 null bytes

0, # 100 - ? 0
256, # 102 - ? 0x0100
$filesize/2, # 104 -

1. Next comes an array of positions, which seems
2. to be a sort of 'play until' set of instructions
3. 150 - Description

"Grandstream standard music ring";

1. sanity check

$headerlen = length $header;
die "header length wrong ($headerlen)\n" unless $headerlen == 512;

1. add the audio

$header .= $audio;

1. compute the checksum

$checksum = unpack "%16n*", $header;
printf "checksum before = %04x\n", $checksum;

1. insert it in the correct place

substr($header,4,2) = pack "n",-$checksum;

1. ensure the new checksum is zero

$checksum = unpack "%16n*", $header;
printf "checksum after = %04x\n", $checksum;
die "checksum failed\n" unless $checksum == 0;

1. write the file

open F, ">$filename" or die "can't open output file $filename: $!\n";
print F $header;
close F;

1. end