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

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  #1  
Old 2006-05-10, 03:01 PM
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Are these lossy?

Hi.

Without noticing there was a whole section devoted to "lossy or not" I sent a private message to Five on Dimeadozen.org yesterday. So I thought I would post my question here too. Below is the message I sent Five :


I was checking some of the shows I have just recieved and I've got some suspicious spectral and freq graphs. And remembering you were experienced in detecting the source of audio files, I thought maybe you could take a look at them and let me know what you think about their possible sources...

If memory serves, I recall you don't support EAC for analysing audio but this is the only program I'm familiar with and till next month I won't have time to get used to another one and I thought maybe these graphs will also serve the purpose, so graphs from EAC are what I have.

In the frequency graphs of many shows, you'll notice, there's a drop off around 12-13 khz which is the main thing that made me suspicious. Because according to the audiohub page explaining how to detect mp3 audio (http://www.audiohub.org/get/fa/fa.htm) a drop-off caused by a mp3 source happens around 17-19 khz while on a mini-disc sourced audio this happens around 13-14 khz. The drop-offs however are not really so sudden drop-offs; they just tend to descend quickly after that point, that's all.

A line slicing the view on almost each spectral graph makes me think this is due to some remastering etc.. Because again according to audihub-mp3-detection-guide the spectral analysis shouldn't look so unnaturally tidy and linear. But I see this horizontal line in spectral analysis of many shows; do you know what casuses this? Is it really due to some remastering etc.?

Now I know that Leonard Cohen - 1993-05-27 - Frankfurt and Leonard Cohen - 1993-05-28 - Munich are DAT recordings. Also, Liveman (you know him, don't you?) told me his own copies of these shows produce the same graphs, and that he thinks the results are due to (maybe) the OKM mics used to tape the show, or some mastering process; so at least for those shows I am a bit relieved. Liveman also told me the same taper taped also the Leonard Cohen - 1988-06-01 - Royal Albert Hall, London show but with different equipment.

Anyway, I have included spectral+freq analysis for 2-3 tracks from each show that I am suspicious about. If you can take a look at these graphs I'd really appreciate it and be forever thankful.

You can download the graphs from :

http://rapidshare.de/files/20011763/Are_these_lossy.rar.html

I hope I'm not putting too much weight on you... I am, I guess. So please forgive me.

Thanks in advance.

Regards to all.
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  #2  
Old 2006-05-10, 04:40 PM
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Re: Are these lossy?



I wasn't on DIME yesterday so I saw it here first

noticing a steep dropoff in the fa is certainly cause for suspicion but it is not conclusive. also, mp3s and MDs can drop off at different frequencies, depening on the encoder & settings.

I'll get a chance to look at the samples you've provided tonight or tomorrow.
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  #3  
Old 2006-05-10, 04:42 PM
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Re: Are these lossy?

Quote:
Originally Posted by Five


I wasn't on DIME yesterday so I saw it here first

noticing a steep dropoff in the fa is certainly cause for suspicion but it is not conclusive. also, mp3s and MDs can drop off at different frequencies, depening on the encoder & settings.

I'll get a chance to look at the samples you've provided tonight or tomorrow.

Thanks Five.

I'm looking forward to hearing (good news) from you.

Regards.

Kagan.
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Old 2006-05-14, 06:09 AM
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Re: Are these lossy?

Quote:
Originally Posted by Five


I wasn't on DIME yesterday so I saw it here first

noticing a steep dropoff in the fa is certainly cause for suspicion but it is not conclusive. also, mp3s and MDs can drop off at different frequencies, depening on the encoder & settings.

I'll get a chance to look at the samples you've provided tonight or tomorrow.

Sorry to bother you Five, but could it be you have forgotten about my request from your kindness to take a look at my samples?
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  #5  
Old 2006-05-14, 05:27 PM
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Re: Are these lossy?

tha't okay, man. you are right this one kind of slipped my mind.

hard to really see what's going on using EAC for analysis... could you provide some flac samples via yousendit.com / rapidshare.de perhaps?

also check here for some info on better tools that are available online.
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  #6  
Old 2006-05-14, 05:36 PM
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Re: Are these lossy?

Quote:
Originally Posted by Five
tha't okay, man. you are right this one kind of slipped my mind.

hard to really see what's going on using EAC for analysis... could you provide some flac samples via yousendit.com / rapidshare.de perhaps?

also check here for some info on better tools that are available online.
Thanks.

My uploading capabilities are limited but I can cut 10-20 seconds of audio from each track and upload them. Would 20 seconds be enough to analyze the source?
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  #7  
Old 2006-05-14, 08:12 PM
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Re: Are these lossy?

Quote:
Originally Posted by Five
tha't okay, man. you are right this one kind of slipped my mind.

hard to really see what's going on using EAC for analysis... could you provide some flac samples via yousendit.com / rapidshare.de perhaps?

also check here for some info on better tools that are available online.
Here are 20 second samples from each show in question.

http://rapidshare.de/files/20479406/Segments.rar.html

Thanks a lot for your effort to help me.

Looking forward to hear from you soon.

Regards.

Kagan.
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Old 2006-05-15, 12:51 AM
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Re: Are these lossy?

1974-09-18

I'd say this one is lossy
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File Type: gif lc1974-09-18sa1.gif
( 137.0 KB, 66 views)
 
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Old 2006-05-15, 12:54 AM
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Re: Are these lossy?

1974-09-24

also lossy... looks like the exact same encoder settings as the previous
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  #10  
Old 2006-05-15, 01:03 AM
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Re: Are these lossy?

1985-03-06

I'm not sure what to say about this one... the cutoff is very straight in the sa, but fa looks normal. sounds brittle and somewhat distorted but not really like an mp3. so I'd call this less than ideal, but lossless so far as I can ascertain (other opinions?)

sa:
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( 145.9 KB, 63 views)
 
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  #11  
Old 2006-05-15, 01:04 AM
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Re: Are these lossy?

1985-03-06 (same show)

fa:
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  #12  
Old 2006-05-15, 01:10 AM
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Re: Are these lossy?

1988-06-01

lossy... looks like the same encoder settings used on the 1974 shows above.
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( 138.3 KB, 62 views)
 
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  #13  
Old 2006-05-15, 01:13 AM
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Re: Are these lossy?

1993-05-04

lossy

again, looks like it was encoded by the same person who did the '74 shows. also, very audible artifacts on all these as well.
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  #14  
Old 2006-05-15, 01:16 AM
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Re: Are these lossy?

1993-05-10

lossy again

again, looks & sounds like the '74 shows
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  #15  
Old 2006-05-15, 01:20 AM
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Re: Are these lossy?

1993-05-11

lossy

again like the '74 shows
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