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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>If all you want to do is find the first audio frame, you don’t
necessarily need to know the ID3v2 tag length. (If you do need the
length, it’s clearly spelled out in the spec.) Do a search on MPEG
header and you’ll find the byte pattern which identifies the start of an
audio frame. One location for this information is at http://www.mp3-tech.org/
in the Programmer’s Corner section. (In writing my .NET tag editor
library, I decided to add support for MPEG data like bit rate and frequency,
and this is the page I used as a reference.)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Mitchell S. Honnert<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>www.UltraID3Lib.com<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> Silas Pradetto
[mailto:silas@sonoroussound.com] <br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, January 25, 2006
2:22 PM<br>
<b><span style='font-weight:bold'>To:</span></b> <st1:PersonName w:st="on">id3v2@id3.org</st1:PersonName><br>
<b><span style='font-weight:bold'>Subject:</span></b> [ID3 Dev] First byte of
the first frame: the inevitable byte (revised)</span></font><o:p></o:p></p>
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<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>thanks, the files
encoded by different encoders I would consider to be different, i only want
to detect files that i may have downloaded twice and are in different dirs,
and someone may have changed the tag on one not the other, but the file is
the same otherwise. thanks for the suggestion on the already-done dup
remover, as i have no real time for writing this stuff anymore, the other
question is how to find the length of the ID3v2 tag???<br>
<br>
thanks again,<br>
<br>
silas<o:p></o:p></span></font></p>
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<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>If you really want to
reinvent the wheel you can -- you have to determine how long the ID3v2 tag
is, skip that, then read the rest of the file (excepting the last 256 bytes
if it has an ID3V1 tag). How you do this depends entirely on the library (if
any) you use. Note that if all you do is a byte-by-byte comparison then you
still won't detect dupes if the files were encoded by different encoders, or
at different bitrates, or various other issues. <br>
<br>
If you don't want to reinvent the wheel, then go take a look at <a
href="http://musicbrainz.org">musicbrainz.org</a> -- they've already done
this. And taken care of the various issues I listed above.<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'>On 1/25/06, <b><span style='font-weight:bold'>Silas
Pradetto</span></b> <<a href="mailto:silas@sonoroussound.com">silas@sonoroussound.com</a>>
wrote:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'>I recently became added to this system of emails,
and I am trying to write a program to find duplicates in MP3's. I wish to
only take into consideration the actual song data, not bytes of any tags.
Therefore, how do I find the first byte in the file of actual song data, ie
the first byte of the first frame? I want to be able to detect duplicates
that have different tags but are the exact same audio information. Also, to
make the program faster, I would like to know where to find certain info such
as bitrate, length in seconds, etc, so when I am scanning my 100000 song
library I don't have to check bytes if the songs are obviously dissimilar.
Thanks very much. Oh, and I mostly do VB 6, though I do know some C++, so if
you are going to talk about file I/O stuff please refer to VB if you can. <br>
<br>
Silas<br>
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