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[To: sebastian@trueg.de, mad-dev@lists.mars.org]
On Thu, 7 Nov 2002, Sebastian Trueg wrote:
Hy list, is there a good and fast way to test if a file actually is a mp3 file or not? My attempts with decoding some bytes at the beginning of the file do not work...
I was thinking about this problem recently. I was planning on implementing the following.
Read the first 4 bytes A B C D
if ABC = ID3, then it's MP3 (It might be better to skip the ID3 header and then ensure the following holds)
or if ABCD form a valid MP3 header, then it's MP3. Otherwise not MP3.
To check if it's a valid header, I'd ensure
A = FF B & 0xE0 = E0 B & 0x18 != 0x08 B & 0x06 != 0 C & 0xF0 != 0xF0 C & 0x0C != 0x0C D & 0x03 != 0x02
I'd be interested in other's opinions of this detection algorithm.
- -- Russell O'Connor http://www.math.berkeley.edu/~roconnor/ ``[Law enforcement officials] suggested that the activists were stopped not because their names are on the list, but because their names resemble those of suspected criminals or terrorists.'' -- SFGate.com