Universal MG embed an audible watermark in downloads (article@post#30), Was: FLAC file with artefacts not present on original CD? Options

[mannheim]

This is my first post in these forums.

Can anyone help me guess the source of some audible artefacts in some downloaded music?

I have two FLAC files for the same classical track (Tchaikovsky's 5th Symphony, Markevitch, on a Philips label). One was purchased from Passionato, the other was purchased from UMG's web site. Although both are supposed to be lossless copies of the data on the original CD, the FLAC file from Passionato actually has a clearly audible sort of "flutter" in some quiet, sustained passages. It is not the same as the UMG file. The difference isn't subtle. (Having read the TOS, I did do an ABX test. But it hardly seemed necessary in this case: I got 10/10 without difficulty. I will upload the short samples that I used.)

My guess was that the Passionato download was actually derived from a compressed audio file, converted to FLAC. But I'm puzzled. Compressing the UMG file and then converting back to FLAC did not give me a result that was in any way comparable, whatever compression I tried. The UMG and the Passionato file have exactly the same number of samples, and the difference of the two wave forms has a spectrum which is mostly in the range of about 1000 Hz - 2500 Hz, with very little above that.

Another possibility is that both FLAC files were obtained from some (fairly high quality) compressed source -- say MP3 -- but that the Passionato file was decompressed using software with a bug. I have quite a few FLAC files from Passionato. All the files from UMG labels exhibit this "flutter", with the exception of the most recent one I purchased.

I will edit this post when I have a link to the samples. I'll upload 7 seconds of each of the two FLAC files, and also the difference of the two wave forms (amplified). The difference sounds like fragments of the original tones together with higher "chirps". (I read the TOS concerning differences of wave forms, but I think the difference is interesting in this case.)

Edit: The uploaded FLAC samples are here.

This post has been edited by mannheim: Jul 21 2011, 18:56

[Wombat]

I guess I am leaning to the explanation suggested by greynol: some sort of watermarking. Reading around, it seems that Universal Music do add watermarks to the files they provide to online music stores. And perhaps heavy-handed watermarking might lead to these artefacts

If this comes thru to be true i´d say this is scandalous!! Why to pay for a lossless version that adds much more noise as any modern lossy encoding does?
Time to write an Email and complain directly at them asking for clarification. Will be interesting how they explain it to you.

[mannheim]

If this comes thru to be true i´d say this is scandalous!! Why to pay for a lossless version that adds much more noise as any modern lossy encoding does?
Time to write an Email and complain directly at them asking for clarification. Will be interesting how they explain it to you.

Well I don't want to rush to judgement. I did send three emails to Passionato, without any reply. If there is a watermarking problem, then I think it is more Universal's fault. But perhaps it's just me and I've inadvertently done something stupid? [Edit: Okay, I just read mixminus1's post, above; so I'm probably not crazy.] The only other thing I've found on the web that says someone else has had this problem is this thread on computeraudiophile.com. The orignal poster over there found the problem present in files from passionato but also from iTunes. All the tracks that are mentioned in that thread are on labels belonging to Universal.

This post has been edited by mannheim: Jul 22 2011, 19:44