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cda   music   tracks   file   format

by   wojtek   kaniewski   1997

note:   everything   in   this   file   is   based   on   my   own   investigations.
all   information   that   you'll   find   in   this   text   file   do   not
come   from   microsoft   corp.

cda   files   are   generally   riff   resources.   the   riff   id   of   .cda   file   is
"cdda"   (43h,   44h,   44h,   41h).   they   contain   only   one   data   block
called   "fmt   "   (66h,   6dh,   74h,   20h).   in   current   version   of   .cda   file,
this   block   is   24   bytes   long.   here's   structure   of   it:

offset   length   description
00h      02h       cda   file   version.   currently   equals   1.   if   it   has other   value,   following   data   may   be   out   of   date.
02h      02h       number   of   track.
04h      04h       cd   disc   serial   number   (the   one   stored   in   cdplayer.ini)
08h      04h       beginning   of   the   track   in   hsg   format.
0ch      04h       length   of   the   track   in   hsg   format.
10h      04h       beginning   of   the   track   in   red-book   format.
14h      04h       length   of   the   track   in   red-book   format.

as   you   see,   time   is   represented   in   two   formats:   hsg   and   red-book.
hsg   can   be   calculated   as   following:

time   =   minute   *   4500   +   second   *   75   +   frame

red-book   is   much   easier   to   use,   because   it   contains   minutes,
seconds   and   frames   in   unmodified   form,   byte-packed:

offset   length   description
00h      01h       frame
01h      01h       second
02h      01h       minute
03h      01h       not   used

now,   i'll   show   you   an   example   file.   first   part   is   a   hex   dump
of   the   file,   the   second   is   the   explanation   of   the   fields.

52   49   46   46   24   00   00   00   43   44   44   41   66   6d   74   20   riff$...cddafmt
18   00   00   00   01   00   04   00   b8   24   f6    00    f7    11   01   00   .........$......
b4   5c   00   00   0a   25   0f    00   20   10   05   00                                    ./...%..   ...

01   00   -   first   version   of   cda   file   :)
04   00   -   fourth   track
b8   24   f6   00   -   serial   number   of   cd   in   cdplayer.ini   is   [f623b8]

f7   11   01   00   -   begining   of   track   in   hsg   format
b4   5c   00   00   -   length   of   track   in   hsg   format

0a   25   0f   00   -   begining   of   track   in   red-book   format   (15:37)
20   10   05   00   -   length   of   track   in   red-book   format   (05:16)

that's   all.   it   should   be   enough   to   write   cda   viewer   :)   if   you   need   more
info   or   something   isn't   clear,   feel   free   to   write.

本文标签： 音乐的秘 探索与 密武器

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