Not sure if its lossy...

[Tate]

I need some help on this, I'm not sure if a bootleg I own is lossy or not? I'm always stumped when I think lossy from viewing the spectral view and then I'm not so sure anymore after looking at a frequency analysis.

Info: concert from 1982, soundboard recording. Looking at the spectral, the way it's all black on top and those blocks after close-up, could this be lossy?

Thanks for the help!

[Ted]

I'm still learning this stuff so it's fun to guess and then see what the experts say.

I'm GUESSING that it's lossless because there is no definite cut-off all the way up to 20k, looking at SA1.

The blocks in SA2 are due to you "zooming in" on the file. That's what digital looks like - no wavey lines, only blocks - again, only a guess.

Now, a question from me, for the experts:

Refer to the VERY faint spikes on either side of each "block" in SA2. Is that due to the noise made by the "switches" in the electronics (A/D converter, or whatever) of the computer itself? (or whatever electronic device recorded that file)

[AAR.oner]

i would venture to say lossy...yer dropping off around 18-19kHZ...in the SA, yer getting *black* above this freq. range, and the blocks seem too *blocky* for lossless...i'd wait for Five or one of the other experts before ruling, but that'd be my analysis

do you know what the source is [other than just SBD]? was it from an FM broadcast per chance?

[Ted]

Originally Posted by AAR.oner

...the blocks seem too *blocky* for lossless...

Even though it's only ~2sec sample? I don't recall exactly at what resolution the "Wave" becomes blocky, so I coudl be wrong (I was once before, I think)

Where's Five, when ya need him?

[Five]

here I am

yes, this is lossy. it is high-quality lossy of some sort, I've seen this "signature" several times before. You can even see it zoomed out, but when you zoom in you can really see the unmistakable "lego skyline" effect. You can also see the unnatural "staircase" effect in the FA.

Try ripping a couple tracks off one of your favorite commercial cd releases and zoom in to your heart's content using SA and you will not see the lego skyline.

[ffooky]

The "staircase" thing is obviously a specific characteristic of some process as it turns up so frequently and in my experience it's always been on the slightly older recordings.

[Five]

can you post a couple screenshots?

[Ted]

Maybe the staircasing has something to do with sampling rate - lower rate, bigger blocks? I remember zooming in on a .wav before and seeing it - it must have been a .wav from an mp3.

Another lesson for Ted

[Tate]

Thanks for the help guys!!

[ffooky]

Originally Posted by Five

can you post a couple screenshots?

Here you go. These are from a Peter Laughner tape from 1975. The same poster (on STG) seeded a whole load of Laughner material and all of it had the same characteristics.

[ffooky]

And here's another couple. The lineage for these is:

Radio Broadcast-18th March 1967 Master reels > Cassette >CDR >iTunes >Shorten >shtn(Soundboard recording)

This was part of jonsatticuk's Experience in Germany/Sweden etc series and I'd be extremely surprised if there was any digital compression here but you can still see the stairstep/skyscraper effect.

[Tate]

Hmmm, so stairstep/skyscraper doesn't always equal lossy??

[Ted]

Originally Posted by Tate

Hmmm, so stairstep/skyscraper doesn't always equal lossy??

If you're refering to my comments, they're only guesses (sorry for any confusion)

[Five]

Originally Posted by ffooky

And here's another couple. The lineage for these is:

Radio Broadcast-18th March 1967 Master reels > Cassette >CDR >iTunes >Shorten >shtn(Soundboard recording)

This was part of jonsatticuk's Experience in Germany/Sweden etc series and I'd be extremely surprised if there was any digital compression here but you can still see the stairstep/skyscraper effect.

This one looks almost identical to the '82 show in question. There was a Hendrix source in question a ways back that looked exactly like this and we all agreed that it was lossy, perhaps it is even this same one. I'll have to try to dig up the thread. Somebody even posted that they knew what group distributed it and gave the codec & bitrate info. I also saw one Yes show that also has this pattern. So looking at these Hendrix screenshots I conclude that this is also lossy. Yes, I know jon's stuff and it is some of the highest quality Hendrix ever heard but I'm sorry to say IMO this one is lossy like the other we are looking at. When I get a chance I'll dig for that old thread and get the exact encoder settings.

[Five]

there's some very similar looking SAs posted here:
http://www.thetradersden.org/forums/...ead.php?t=4332

I still can't find the thread with the Hendrix show I keep talking about. Maybe we talked about it at TOTM or something. But there's some FA and SA for a Blind Melon show that I got pulled from EZT where it had this lego skyscraper pattern pretty much identical to the SA we're seeing posted in this thread. I have the original legoless version of that melon show and the SA doesn't have that!