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Gear / Technical Help => Post-Processing, Computer / Streaming / Internet Devices & Related Activity => Topic started by: ~sin213~ on August 26, 2006, 03:26:05 AM

Title: Is there a way to verify a lossless source?
Post by: ~sin213~ on August 26, 2006, 03:26:05 AM

I am pretty sure there is a way to do it, but I don't know how.

If I wanted to know whether a source was truely lossless, is that possible and what program would you use to do it?

I have Audition 1.5 and EAC (of course).  Can either of these programs do it?

Title: Re: Is there a way to verify a lossless source?
Post by: macacopowa on August 26, 2006, 05:28:04 AM

here a link HOw To Detetct an MP3 source http://www.audiohub.org/get/fa/fa.htm
The key are the Frequency and Spectral Analysis

Title: Re: Is there a way to verify a lossless source?
Post by: Ryan Sims on August 26, 2006, 04:19:14 PM

Audition is the best way, IMO.  Check this thread (http://www.thetradersden.org/forums/showthread.php?t=4288) over at The Trader's Den also.  That place is a good resource for this sort of information.

Title: Re: Is there a way to verify a lossless source?
Post by: JasonR on August 26, 2006, 09:20:58 PM

I would argue that, for the most part, you can't tell except with a combination of the supposed source information, and the frequency response, and even then it's rarely certain.  If the source is a 12-bit (ie: LP) DAT recording, or was captured from a radio broadcast, the HF loss above 16kHz that folks identify as MP3 could have nothing to do with MP3 compression at all.

- Jason

Title: Re: Is there a way to verify a lossless source?
Post by: Ryan Sims on August 26, 2006, 11:56:23 PM

Radio is certainly identifiable with the easily visible carrier tone at 19 khz.  The low frequency DAT tapes also have a significantly different appearance from lossy compression when checking the spectrum.  The frequency analysis is not at all the only way to do things.  Spectral analysis reveals much more.

Title: Re: Is there a way to verify a lossless source?
Post by: it-goes-to-eleven on August 27, 2006, 09:06:08 AM

Baudline is one of the better forensic audio tools I know of... It is free but I think linux only.

Title: Re: Is there a way to verify a lossless source?
Post by: pigiron on August 27, 2006, 12:49:06 PM

Quote from: Freelunch on August 27, 2006, 09:06:08 AM

Baudline is one of the better forensic audio tools I know of... It is free but I think linux only.

oh man... this thing's beautiful!  I missed this bugger when I went hunting and ended up using snd. Thanks!

Only wish it was open source.

Title: Re: Is there a way to verify a lossless source?
Post by: ~sin213~ on August 27, 2006, 01:51:49 PM

This is all great info!  I have always wondered how to read those spectral and frequency graphs.  The provided links helped immensly!

Thanx everyone!

Title: Re: Is there a way to verify a lossless source?
Post by: BobW on August 31, 2006, 10:45:13 PM

Don't doubt your ears.

Make 128 bitrate MP3s and compare them to the source wavs.
You will hear the difference on a good system.

Now try it with 192 bitrate MP3s.
Once you know what to listen for from the lower speed samples, the higher speed ones become more discernable.

Spectrum, punch and attack, clarity and accuracy of HF, and that damnable phasiness is what I hear as big differences.

Verify ?  Not 100% without knowing the processing chain. There is no header that passes on a file which shows that it is decoded from an MP3 to my knowledge.

 It's all about the sound.

(http://img.photobucket.com/albums/v114/bobw1/MP3_Sucks.gif)