PDA

View Full Version : TLH says track looks like MPEG with probability 95%?


jeeweewee
2007-06-27, 07:34 AM
Hi everybody,

I've downloaded some flacs (from another torrentsite) and when tested with TLH is says that all tracks looks like MPEG with probability 95% (or around). Does this mean that somebody down the line 'upgraded' mp3's to flacs?

peace, jeeweewee :wave:

U2Lynne
2007-06-27, 10:27 AM
Your best bet at this point it to do a Sprectral and Frequency analysis on a track - usually a two second part in the middle of the track. Take a look at our Lossy or Lossless (http://www.thetradersden.org/forums/forumdisplay.php?f=47) forum. There are some links on the top about how to do this and several threads where users posted their results and asked for opinions.

jeeweewee
2007-06-27, 11:27 AM
Thanks for the info. Will have a look at these.

Five
2007-06-27, 06:34 PM
don't only go by what TLH tells you it gives false results rather easily.

guygee
2007-06-28, 05:49 AM
jeeweewee - Lynn and Five's advice is right on.

If you are interested, here is my long answer :-)

I would add that TLH is using a little program called auCDtect (http://true-audio.com/Tau_Analyzer_-_Aucdtect_Algorithm_Details) to try and detect mp3's. The problem with auCDtect is it gives many false positives: it flags many files that are not mp3s as being possible mp3s. However, that is not necessarily a "bad thing" if you understand what it is doing, because the files that do get flagged usually have "something" wrong with them. The most common types of problems that get flagged by auCDtect besides mp3s are heavily NR'ed files, files that have been heavily low-pass filtered, and other kinds of lossy files like ATRAC and 32KHz dat. Every once in a while, though, auCDtect will flag a normal FM or TV recording, so just be aware of that too.

As Lynn says, if a file gets flagged as mp3 by auCDtect, take a look at the FAs and SAs and see what is wrong. Usually, you will see something undesirable, although it may not be an mp3.

False negatives are less of a problem with auCDtect: very few mp3s will not be detected (none so far for me). So for me it is worth using. Instead of using it through the TLH frontend I have it set up as a batch file so that I can just right click on any directory and it will check all of the lossless music files in that directory and all subdirectories. It is still something of a hassle to use (has to convert to wav, then crunches a lot of numbers), so I mostly use it if I do not know a seeder, for spot checks, and *always* if I am seeding a show myself (and if I am seeding, I still check the FAs and SAs anyways, lol).