See near the bottom for the interesting bit :-)
In article [EMAIL PROTECTED],
Stephen R. Besch [EMAIL PROTECTED] wrote:
I did a little detective work and here is a summary of what I found out.
In version .63 of the firmware, the ringtone files are all nearly
identical (at least they contain the same audio data stream). From this,
and from the format of the hex data in the header, I was able to
discover the location and format of the checksum. The idea is that the
only differences in the files were the file name field, the checksum
word and one other value (the 00C8 at offset 26). From this it was
possible to compute the difference in checksum expected and show that
the only value in the file that changed appropriately was at offset 2.
It also revealed the means of calculating the checksum.
I've just been playing with these files too. You can play the audio using:
tail +513c ring1.bin | play -t ul -
Here is a partially decoded header:
Hex Offset Typical Value Function
00 ? Always zero (6 sample files)
027F90 File length in 16-bit words (bigendian)
043450 Checksum (see below)
060100 Version number
0A07D4 Always this value (6 samples)
This is the year (2004)
0C0419 or 0505 ?
The month and day (Apr 25 or May 5)
0E82A, 140B, 142C ?
I assume the time in hh:mm (08:42, 20:11 or 20:44)
10Text filename (eg ring1.bin)
19-25 0's?
260 or 00C8 ?
28-FF 0 ?
100 0100 **See below
102 7F90 repeat of length
104-127 0's?
128 Text String describing file
147-1FF 0's?
200-end Audio Data
The checksum is the value that must be put into location 2 so that a
16-bit sum of the entire file, ignoring overflow, is exactly 0. It is
essentially the negative of the sum of the file computed with a zero
value in the checksum.
Useful information. I think there's enough there to recreate these files
now (don't know about the or 00C8 at offset 26 though).
OK, while composing this post I decided to write a perl program to read
a uLaw stream on standard input and create a suitable header, writing
the result to an output file.
It can be found at http://www.softins.co.uk/makering.pl.txt
Save and rename to makering.pl. Usage is described in the file, but here
is an example:
sox inputfile -r 8000 -c 1 -t ul - rate | makering.pl ring1.bin
(try using /usr/share/sounds/phone.wav for the inputfile)
After putting the ringN.bin file into /tftpboot and rebooting my phone,
amazingly enough it works! I now have a new ringtone.
Time for bed
Cheers,
Tony
--
Tony Mountifield
Work: [EMAIL PROTECTED] - http://www.softins.co.uk
Play: [EMAIL PROTECTED] - http://tony.mountifield.org
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