On Wed, 1 Oct 2014 10:54:33 +0200 Egor Sanin <egor.sanin@xxxxxxxxx> wrote: > Dear community, > > While not directly a linux related question, > I am wondering about ultimately using linux > tools for the possible solution, so: > > I get the feeling at times, when getting music > from torrents and such, that not all files > claiming to be flac are actually lossless. > It seems that sometimes folks will take an > mp3, reencode it in flac and distribute the > result. > > Now the question is whether it is possible to analyze an > audio file encoded in a lossless format and > determine if it existed as a lossy file in a > previous life? > > Any insight is appreciated. > > Thanks. Hi Egor, once upon a time I read a lot about audio codecs on http://www.hydrogenaud.io/forums/. Note that this is a codec focused forum, not a free software focused one, but people like the lame and ogg developers do (or used to) read and write at those forums AFAIK. I also remember that there was some windows tool for the purpose you describe but I can't recall the name. Anyway, AFAIR it used the techniques already described, spectral analysis to detect lowpass filtering. There are some artifacts of the mp3 codec that allow for rather reliable detection, pre-echos come to mind. You are likely able to train yourself to listen for these artifacts, but you may not be able to un-train yourself ;) Regards, Philipp _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
