2 thoughts on “Rainbow 1981-06-13 Rotterdam 1981 (Black Box)”

1. It was this bootleg you were wondering about regarding its losslessness or lossiness, right?
   First of all, Trader’s Little Helper’s lossiness test frequently produces false negatives as well as false positives, which is why I don’t use it anymore.
   Here’s how this recording’s spectrum zoomed to 2 seconds looks with Cool Edit Pro 2.1:
   https://i.imgur.com/M8b90KR.png
   I don’t see anything there that would suggest lossy lineage. It looks like any lossless recording to me. The horizontal line you mentioned is probably just due to some kind of static noise in the recording. It is quite common for recordings to show that kind of line, I have seen it a lot. It has nothing to do with lossy lineage. A frequency ‘haircut’ and/or ‘lego bricks’ are what you have to look for. Lines like this one, in contrast, aren’t problematic.

   A few more general words about lossiness testing: There is no secure method. There just isn’t, and I guess there can’t be. Audio recordings have certain characteristics that we can identify. They don’t tell us how those characteristics came to be. Thus, lego blocks can be produced by MP3 compression – or by denoising/dehissing procedures. Technically, both MP3 compression and denoising are ‘lossy’ because they can never be reversed without a loss (compared to the original signal). But the same is true for many other processes that we usually don’t mind (at least not as such), like EQing. (EQing does not usually produce the artifacts that we tend to interpret as symptoms of lossiness though.)

   Even in the case of this Rainbow bootleg, my statement that I don’t see anything there that would suggest lossy lineage doesn’t imply it’s impossible that this recording has lossy lineage. Instead, what I am saying is merely that I don’t see any REASON to assume this was lossy. It is still possible though, because any lossy recording can, intentionally or by accident, be tampered with in such a way as to conceal the lossiness artifacts. Thus, if you have an MP3 file, and play it and record it to analog cassette tape and then record it back to a WAV file on your computer, chances are that it will appear perfectly lossless because the tape noise concealed the frequency haircut and/or lego bricks that were originally induced by the MP3 compression. Alternatively, you could use sound-processing software to create white noise, to the same effect. It’s not common, but it has been done, e.g. with some allegedly lossless copies of Black Sabbath 1970 Montreux that turned out to be lossy and manipulated with white noise in order to conceal the lossiness artifacts. And again, when a recording does show the typical lossiness artifacts, it it still possible that it was never compressed using a lossy codec; maybe it has just been denoised.

   Anyway, why so many other commercial (especially, but not exclusively, CDR bootlegs) bootlegs do show those artifacts, remains a mystery to me, given that about 97 % of those recordings have been widely circulated in lossless quality for many years. Denoising seems to be the most plausible explanation. Of course there’s softer, less crude ways of denoising that don’t produce lego blocks or haircuts; on the other hand, most consumers don’t seem to know or care about lineage anyway, so maybe the bootleg companies simply don’t feel the need to be careful with the quality of their recordings. I don’t know.

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   1. Thanks for the detailed explanation—and for taking the time to look at this bootleg!

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