The Traders' Den  

  The Traders' Den > Where we go to learn ..... > Technobabble > Lossy or Lossless?
 

Notices

Lossy or Lossless? Please use this forum to post spectral and frequency analysis posts about shows you have your doubts about.

Reply
 
Thread Tools
  #1  
Old 2005-03-16, 10:20 AM
KingBongo
0.00 KB/0.00 KB/---
 
Strange (for me) frequency analysis

Hi,
I have recently acquired a very nice Cohen show, for which unfortunately it came with no lineage whatsoever . Of course this means I cannot post it here, but I was wondering if someone could help me understand the strange frequency analysis results I get and let me know if there is lossy ancestry. There is definitely a drop, but then it looks fine at higher frequencies .

Here is the frequency analysis and the spectral view from EAC (let me know if you need anything else). To me it looks like somebody hacked away a range of frequencies, but would anyone know how that could happen?

Any help would be much appreciated and I thank you in advance.
Attached Images
File Type: gif freq.GIF
( 21.4 KB, 98 views)
 
File Type: gif spec.GIF
( 149.9 KB, 97 views)
 

Last edited by KingBongo; 2005-03-16 at 10:29 AM.
Edit/Delete Message Reply With Quote Reply with Nested Quotes
  #2  
Old 2005-03-16, 11:37 AM
wazoo2u wazoo2u is offline
923.61 MB/96.22 MB/0.10
 
Join Date: Nov 2004
Re: Strange (for me) frequency analysis

I would agree with you.

It's a totally FUBAR'ed audio signal. Not a product of a Codec. Why would someone do this ?? Only through ignorance or incompetence, not knowledge or skill.
Reply With Quote Reply with Nested Quotes
  #3  
Old 2005-03-16, 12:27 PM
uhclem
0.00 KB/0.00 KB/---
 
Re: Strange (for me) frequency analysis

Looks like a botched de-hiss/NR job. But RainDawg is the guy to ask about this.
Reply With Quote Reply with Nested Quotes
  #4  
Old 2005-03-16, 01:44 PM
RainDawg's Avatar
RainDawg RainDawg is offline
Renegade Geek
10.20 GB/20.72 GB/2.03
 
Join Date: Oct 2004
Location: Passing swiftly through The Moor
Re: Strange (for me) frequency analysis

Uh-huh, that was my first impression upon looking at it too. Someone noticed some hiss or noise (likely someone who aslo doesn't know the difference between the two) and tried to remove it. To this person, I am sure this was a fantastic result...

This appears to be a prime example of why layman should not tinker with NR, and if they do, why they shouldn't seed their results.
__________________
Through the clouds,
Throught the lies,
We'll never see,
What's never been,
At the ending of life and the coming of death,
Pass not through its gates but into the dark.
Reply With Quote Reply with Nested Quotes
  #5  
Old 2005-03-16, 02:22 PM
paddington's Avatar
paddington paddington is offline
please look after this bear
TTD Staff
83.17 GB/882.10 GB/10.61
 
Join Date: Jan 2005
Location: UK
Re: Strange (for me) frequency analysis

it looks like a friggin notch filter to me. I wonder of there was some terrible 11khz squeal on the tape or something. Or something sweeping between 10k and 12k, where he notched it.

I take it you have no idea how it was recorded, right?
__________________
"There are some of these recordings where it is just a whirring, and you cannot hear the music. " - Jimmy Page, 2007 / JUL / 26
Reply With Quote Reply with Nested Quotes
  #6  
Old 2005-03-16, 06:30 PM
Five's Avatar
Five Five is offline
TTD Staff
186.65 GB/588.32 GB/3.15
 
Join Date: Oct 2004
Location: Canada
Re: Strange (for me) frequency analysis

I've seen this twice, one was a cdr transferred MiniDisc a client gave me recently, the other was a transfer from a VHS tape I made myself. I'm stumped as to how this "death star groove" happens, but on the bright side this doesn't look like a lossy source to me.

Thanks KingBongo for all the rare Cohen you continually unearth.
__________________
Checksums Demystified EAC Config MakeTorrent WinAmp Config

Modern social theory casts a highly skeptical eye on any declaration that a group of persons is without conflict, and insists, on the contrary, that conflict is natural to groups, and even more, is essential to them. -Patrick Henry
Reply With Quote Reply with Nested Quotes
  #7  
Old 2005-03-16, 07:03 PM
ssamadhi97's Avatar
ssamadhi97 ssamadhi97 is offline
meow.
87.81 GB/69.41 GB/0.79
 
Join Date: Nov 2004
Location: Old Europe
Re: Strange (for me) frequency analysis

Err? What's with all this Noise Reduction talk here? I see NO evidence whatsoever for NR here.

Actually it's blatant aliasing introduced by bad resampling from 22.05kHz to 44.1kHz (check how the content above 11.025kHz is more or less just a flipped image of what's below). The "dropout" is there because the signal was lowpassed at 10kHz before this resampling process for some reason. Maybe a lossy audio encoder operating at a rather low bitrate. Who knows.

"If it sounds like ass, it's probably sourced from a 56kbps 22050Hz mp3" >_>
Reply With Quote Reply with Nested Quotes
  #8  
Old 2005-03-16, 08:59 PM
uhclem
0.00 KB/0.00 KB/---
 
Re: Strange (for me) frequency analysis

Quote:
Originally Posted by ssamadhi97
... (check how the content above 11.025kHz is more or less just a flipped image of what's below) ...
I had noticed this but couldn't account for it. Well I'll be damned.
Reply With Quote Reply with Nested Quotes
  #9  
Old 2005-03-16, 10:01 PM
wazoo2u wazoo2u is offline
923.61 MB/96.22 MB/0.10
 
Join Date: Nov 2004
Re: Strange (for me) frequency analysis

Quote:
Originally Posted by ssamadhi97
Actually it's blatant aliasing introduced by bad resampling from 22.05kHz to 44.1kHz (check how the content above 11.025kHz is more or less just a flipped image of what's below). The "dropout" is there because the signal was lowpassed at 10kHz before this resampling process for some reason. Maybe a lossy audio encoder operating at a rather low bitrate. Who knows.

"If it sounds like ass, it's probably sourced from a 56kbps 22050Hz mp3" >_>
Nice lesson ssamadhi. Thanks. I didn't notice the duplication in the freq graph, but to be honest, I was just transfixed by the huge notch

Good to always be learning the fine points.... Thanks for sharing an excellent observation.
Reply With Quote Reply with Nested Quotes
  #10  
Old 2005-03-17, 03:50 AM
KingBongo
0.00 KB/0.00 KB/---
 
Re: Strange (for me) frequency analysis

Thanks for all the info... it went a little bit beyond what I can understand (ssamadhi97's answer seems to find consensus, but I >think< I managed to spot it as it flew really high above my head ).

The original source is supposed to be SBD, but from what you say someone did a conversion somewhere and/or resampled the signal and totally botched it... sad, really, it's a magnificent show. I guess I can consider it as NOT MP3-sourced but lossy in other ways, right?
Reply With Quote Reply with Nested Quotes
  #11  
Old 2005-03-17, 11:18 AM
paddington's Avatar
paddington paddington is offline
please look after this bear
TTD Staff
83.17 GB/882.10 GB/10.61
 
Join Date: Jan 2005
Location: UK
Re: Strange (for me) frequency analysis

it could be labeled

"FUBARed by junior's mastering studio"
__________________
"There are some of these recordings where it is just a whirring, and you cannot hear the music. " - Jimmy Page, 2007 / JUL / 26
Reply With Quote Reply with Nested Quotes
  #12  
Old 2005-03-17, 08:00 PM
ssamadhi97's Avatar
ssamadhi97 ssamadhi97 is offline
meow.
87.81 GB/69.41 GB/0.79
 
Join Date: Nov 2004
Location: Old Europe
Re: Strange (for me) frequency analysis

Quote:
Originally Posted by KingBongo
I guess I can consider it as NOT MP3-sourced but lossy in other ways, right?
Oh I definitely would not rule out mp3 compression before the bad resampling step.. just can't seem to come up with a n00b-friendly way of figuring out wtf is going on right now.
Reply With Quote Reply with Nested Quotes
  #13  
Old 2005-03-17, 10:12 PM
Five's Avatar
Five Five is offline
TTD Staff
186.65 GB/588.32 GB/3.15
 
Join Date: Oct 2004
Location: Canada
Re: Strange (for me) frequency analysis

Quote:
Originally Posted by ssamadhi97
Oh I definitely would not rule out mp3 compression before the bad resampling step.. just can't seem to come up with a n00b-friendly way of figuring out wtf is going on right now.
How can I reproduce this groove in a controlled environment?

thanks for the lessons.
__________________
Checksums Demystified EAC Config MakeTorrent WinAmp Config

Modern social theory casts a highly skeptical eye on any declaration that a group of persons is without conflict, and insists, on the contrary, that conflict is natural to groups, and even more, is essential to them. -Patrick Henry
Reply With Quote Reply with Nested Quotes
Reply

The Traders' Den > Where we go to learn ..... > Technobabble > Lossy or Lossless?

Similar Threads
Thread Forum Replies Last Post
Strange frequency - cobain72 Technobabble 6 2008-04-13 03:42 PM
Spectral and Frequency analyses - reese Technobabble 3 2008-02-25 08:11 PM
FM or TV Spectrum/Frequency? - NoddingTurdFAN Lossy or Lossless? 3 2005-05-01 08:36 PM
frequency analysis - uah21 Lossy or Lossless? 2 2005-01-05 02:54 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forums


All times are GMT -5. The time now is 05:12 PM.


Powered by: vBulletin, Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright ©2004 - , TheTradersDen.org - All Rights Reserved - Hosted at QuickPacket
no new posts