withmorten / spek-alternative

Acoustic spectrum analyser
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metadata/headers are affecting the look of the spectrograms #17

Open alexjcode opened 1 year ago

alexjcode commented 1 year ago

bug was produced using mac version 0.8.2.3

putting 2 identical mp3s with different metadata into spek produces 2 slightly different looking spectrograms, even when the underlying audio data is identical. (i stripped away the metadata of both files and they had matching md5 hashes. the spectrograms also matched perfectly when their metadata was removed)

File A

original mp3 (metadata mistakenly showed a duration of 74:33:55 when it was really 2:40)

original file  169FBB88 mp3

File B

original mp3 -> metadata modified by mpTrim to show the correct duration which is 2:40 (underlying audio data of B is still identical to A)

header fixed w mpTrim  A76C57E3 mp3

File C

original mp3 -> metadata cleared with TagStripper or original mp3 -> metadata modified by mpTrim -> metadata cleared with TagStripper

the spectrograms i got from spek for A and B were different, yet the filesizes were very similar, so i cleared the metadata of both files using TagStripper. the 2 resulting files with cleared metadata had identical md5 hashes, so basically they were the same file. thus, the underlying audio data of A and B must also have been the same

metadata cleared  2D5B0B31 mp3

also curious was that neither A nor B's spectrogram matched up with C's. this feels like a pretty widespread bug that should be easy to duplicate