Not sure if its lossy... [Archive]

Tate

2005-07-01, 09:49 AM

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

2005-07-01, 11:06 AM

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

2005-07-01, 11:25 AM

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

2005-07-01, 11:29 AM

...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) :p

Where's Five, when ya need him?

Five

2005-07-01, 03:15 PM

here I am :D

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

2005-07-01, 03:28 PM

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

2005-07-01, 04:25 PM

can you post a couple screenshots?

Ted

2005-07-01, 04:46 PM

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

2005-07-01, 11:13 PM

Thanks for the help guys!!

ffooky

2005-07-02, 02:40 AM

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

2005-07-02, 03:09 AM

Tate

2005-07-02, 06:44 AM

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

Ted

2005-07-02, 07:51 AM

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

2005-07-02, 08:41 AM

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

2005-07-02, 08:50 AM

ffooky

2005-07-02, 09:44 AM

there's some very similar looking SAs posted here:
http://www.thetradersden.org/forums/showthread.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!

Dead right about the Blind Melon being the same as this.

So is the consensus that stairs in the FA/Skyscrapers in the SA=Minidisc ? Sounds feasible to me but what I'd really like is for someone to take a 100% kosher file and replicate those features with minidisc.

Five

2005-07-02, 08:59 PM

well I don't think it's MD I think it's high bitrate cbr mp3. but we all agree that it is lossy as f*ck.

ssamadhi97

2005-07-02, 09:59 PM

Hmmm, so stairstep/skyscraper doesn't always equal lossy??
As of yet I am quite confident that it's safe to say that stairstep/skyscraper implies lossy. However the reverse (lossy implies stairstep) is not always the case.

So is the consensus that stairs in the FA/Skyscrapers in the SA=Minidisc ?
The exact kind of skyscrapers presented in this thread seems to imply MD source. However, MD sources do not always look like this.

well I don't think it's MD I think it's high bitrate cbr mp3.
Well I don't think it's high bitrate cbr mp3, I'm pretty sure it's MiniDisc. (I'm referring to pics posted in this thread. If you're referring to something else, sorry, I'm way too tired to read properly now -_-)

Five

2005-07-02, 11:19 PM

oops I meant high bitrate vbr. I know you hate hearing that but it's my opinion. I'm gonna try to figure out how to get that lossy signature and post it up.

ffooky

2005-07-03, 04:14 AM

Does anyone know how Shorten's lossy coding affects things (the second type described here <http://mi.eng.cam.ac.uk/reports/ajr/TR156/node7.html#SECTION00040000000000000000>) ?

I've never managed to get anything approaching the twin characteristics here from any MP3 encoder or AAC and I must say I've never seen them in anything with MD stated in the lineage.

Just an idea.

ssamadhi97

2005-07-03, 03:29 PM

oops I meant high bitrate vbr. I know you hate hearing that but it's my opinion.
Same difference. I'm going to say it over and over again and again, it's generally not possible to tell vbr from cbr just by looking at the spectrum of an mp3 file.

Anyway, the pics presented here are neither vbr nor cbr mp3, they're MD.

Five

2005-07-03, 04:49 PM

doesn't look like any MD signature I've ever seen. if you can up a sample that looks anything like this (or the bmelon) that is sourced from MD I would be shocked to see it. where can I get this sample? nowhere.

Tate

2005-07-03, 08:46 PM

This is very interesting reading all your comments. Whenever you think you got no more to learn about detecting lossy sources, there's always something to discover. Thanks for the help. Keep on discussing.... ;)

range_hood

2005-07-05, 03:27 PM

Looks like Atrac Type R.
Sample is from Hydrogen Audios Listening Test Forum (http://www.hydrogenaudio.org/forums/index.php?showtopic=27321).

http://img68.imageshack.us/img68/2808/atractypersp3dj.th.png (http://img68.imageshack.us/my.php?image=atractypersp3dj.png)

Five

2005-07-05, 04:12 PM

well, there it is I was wrong.

I just couldn't accept the fact that somebody out there is archiving to MD and then converting back to FLAC. it just seemed too far-fetched but it is true.

range_hood, is it okay if we make Minidisc atrac3 LP2/LP4 spectrals into a more generic MiniDisc SA and FA and add this pic?

ffooky

2005-07-05, 06:33 PM

Where are the steps in the FA and the corresponding bands in the SA ?

ffooky

2005-07-05, 06:58 PM

OK, here they are :lol:

Tate

2005-07-05, 07:54 PM

OK, now I'm a bit confused :confused: Since I've never heard of Atrac Type R..... is this a legit format? Have shows been recorded often under that format? (cause I haven't come across these stairsteps/skyscrapers very often..)

Is it an acceptable "lossy" format like MD?

Five

2005-07-06, 03:01 AM

Atrac Type R is one possible codec used by MD (right?). MD is "acceptable" when it is the master source, meaning that a minidisc was recorded at a live show either from mics or sbd not from radio and most certainly not after a CDR/DAT/FLAC/whatever.

e.g.

Mics > MD > EMU0404 > Audacity > FLAC = okay

Mics > DAT(m) > MD(0) > CDR(2) > EAC > FLAC = not okay!

so unless your show was actually recorded using minidisc (highly highly doubtful) it is not a good source for trading.

Tate

2005-07-06, 04:13 AM

OK OK, now I get it. So the bootleg I have was most likely archived on MD... that sucks, the way I see it, that's pretty much the same as converting to MP3 :mad:

Thanks for the explination.

range_hood

2005-07-06, 04:59 AM

I heard that some CD and flashplayers could play Atrac (3 and 3+ only). But mostly Minidisk players use the atrac codec. There is a big faq at minidisc.org (http://www.minidisc.org/minidisc_faq.html).

ATRAC-Version (release year) - [bitrate] - {frequency respose}

ATRAC1-version 1.0 (1992) - [292 kbit/s] - {15kHz}
ATRAC1-version 2 (1994) - [292 kbit/s] - {18kHz}
ATRAC1-version 3 (1995) - [292 kbit/s] - {18kHz}
ATRAC1-version 3.5 (1996) - [292 kbit/s] - {18kHz}
ATRAC1-version 4 (1996) - [292 kbit/s] - {20kHz}
ATRAC1-version 4.5 (MD-Decks; 1996) - [292 kbit/s] - {20kHz}
ATRAC3-version 1.0 (MDLP) (2000) - [132/105/66 kbit/s]
ATRAC1- DSP Type-R (2001) - [292 kbit/s]
ATRAC1- DSP Type-S (2002) - [292 kbit/s]
ATRAC3plus (2003) - [256/64/48 kbit/s]

range_hood, is it okay if we make Minidisc atrac3 LP2/LP4 spectrals into a more generic MiniDisc SA and FA and add this pic?Sure. Would be nice if we could gather samples of all the different versions. Should we keep that at imageshack? the maximum filesize of png files is 100kb here. I would say png are slightly better than gifs.

ssamadhi97

2005-07-06, 08:42 AM

I would say png are slightly better than gifs.
That's kinda like saying "I would say flacs are slightly better than mp3s" :D

(actually it's more like saying "I would say flac is slightly better than adpcm", but what the heck)