[MPlayer-cvslog] CVS: main/libmpdemux demux_audio.c,1.32,1.33
moritz at bunkus.org
Mon Apr 18 16:25:56 CEST 2005
> An acceptable alternative would be brute force scanning, but only
> considering header _chains_ in deciding what type the file is
> (sequences of headers each pointing to the next one, or at least to a
> point before the next one).
Agree. My experience with AC3 and MP3 detection in ogmtools/mkvtoolnix
- garbage is only present at the start of the file (e.g. extracted from
AVIs created with NanDub or other f'cked up software)
- once you find n (e.g. five) consecutive headers you can be pretty sure
that it's a raw MP3/AC3 file. Consecutive means that the next packet
starts exactly at first_pos + first_length
- if you find garbage in the middle then you probably have another file:
MPEG PS/SS, AVI etc. File type detection for such files has to be done
before audio file type detection because both the MP3 and the AC3
headers are not unique enough in their patterns. "RIFF" at file
position 0 ( = AVI) is.
- never underestimate the problem with ID3 tags. Those may appear at the
start of the file. And very, very few files even contain a complete
image in them...
- probing 3000 bytes is definitely not enough. Neither for AC3 nor for
If Darl McBride was in charge, he'd probably make marriage
unconstitutional too, since clearly it de-emphasizes the commercial
nature of normal human interaction, and probably is a major impediment
to the commercial growth of prostitution. - Linus Torvalds
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