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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Hello,<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'>I have a need to verify that mp3 files uploaded by our users
comply with certain minimum specs (bit and sample rates, etc.). To get to
the mp3 headers, I first have to check for an ID3 tag, and if found, use bytes
6-9 to calculate the location of the first mp3 frame. My routine seems to
work in most cases. However, I’ve got one mp3 files that doesn’t
seem to fit the specs, and fails my verification process, although all mp3
players play the file without a problem. Below are the first 13 bytes of
the file:<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'>49 44 33 03 00 00 00 01 79 76 57 4F 41 46<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'>If I am interpreting the ID3 specs correctly, the first mp3 frame
should be found at offset 7D00. However, I only find 00 there; the first
mp3 is really at 7EA1.<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'>Am I missing something? Or did the program that added
the ID3 tag miscalculate the ID3v2 size bytes? If the latter, do all
players allow for mistakes and just start hunting for the 11-bit frame sync?<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'>Thanks in advance,<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><strong><b><font size=2 face=Tahoma><span style='font-size:
10.0pt;font-family:Tahoma'>Robert Sewell</span></font></b></strong><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Trebuchet MS"><span style='font-size:
12.0pt'> </span><o:p></o:p></font></p>
<p class=MsoNormal><font size=3 face="Trebuchet MS"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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