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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 2006-08-13, 10:10 PM
alfienoakes101
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Are these tracks lossy?

Could one of you kind experts please have a look at the following Tau analyses? The top two analyses are track 1 and the bottom are track 2.

Tau has determined that they are MPEG, but the friend who acquired them is convinced that they were WAVE-sourced. Is it possible that Tau got it wrong, and is there anything in the frequency and spectrum analyses that suggests this might be the case?

Thanks,

Tim

[IMG]LOSSY?[/IMG]
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  #2  
Old 2006-08-14, 04:50 AM
Explosivo Explosivo is offline
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Re: Are these tracks lossy?

Looks lossy to me but it might be MD sourced, I dont think Ive seen the cutoff that high before. What show is this? Can you zoom the spectral to about 2 sec? Someone else whos a little more experienced might know.
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  #3  
Old 2006-08-14, 06:54 AM
alfienoakes101
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Re: Are these tracks lossy?

I'll do that shortly, when I work out how to manipulate the photo. It's not from a live show; it's ripped from an official, unreleased record, that's on a CD I have.

The CD is called The La's - Demos, Live & Rarities, and these two tracks are "Timeless Melody" and "Clean Prophet". These versions are found on GOLAS 3. In theory, this should have gone straight from vinyl to WAV.
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  #4  
Old 2006-08-14, 07:05 AM
alfienoakes101
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Re: Are these tracks lossy?

Here's about two seconds. It will probably come out a bit small to view here, but hopefully the resolution is high enough that you'll be able to zoom in if you download it.

Thanks!
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  #5  
Old 2006-08-14, 11:42 AM
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Re: Are these tracks lossy?

the cutoff on MD often goes up to 18kHz (see here).

I'm having trouble fully making sense of the shots you've posted, is it possible for you to upload a 10-20 second sample to yousendit.com / rapidshare.de / megaupload.com or similar and link it here, please?
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  #6  
Old 2006-08-15, 06:50 AM
alfienoakes101
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Re: Are these tracks lossy?

Hi.

I've uploaded a snippet here:

http://www.yousendit.com/transfer.ph...AA808A79976629

Cheers.
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  #7  
Old 2006-08-15, 02:12 PM
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range_hood range_hood is offline
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Re: Are these tracks lossy?

Do you have info about the recording equipment/source? Doesn't look lossless.

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  #8  
Old 2006-08-15, 03:35 PM
alfienoakes101
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Re: Are these tracks lossy?

I don't have any info, except that my source was convinced that it was, and initially received it as a .wav file. What is there to suggest that it is or isn't lossless?
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  #9  
Old 2006-08-15, 04:34 PM
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Re: Are these tracks lossy?

The weak frequency response above ~18kHz. Even if there's just silence there has to be more noise. This can only be done in a digital way.
Here's a sample of a studio cd.



What show is this?
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  #10  
Old 2006-08-16, 10:36 AM
alfienoakes101
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Re: Are these tracks lossy?

Quote:
Originally Posted by range_hood
The weak frequency response above ~18kHz. Even if there's just silence there has to be more noise. This can only be done in a digital way.
It's not from a show, but is a vinyl rip from an unreleased promo, as mentioned above.

I don't understand what your comment means: "...there has to be more noise." Do you mean an MP3 would have more noise or less noise than the sample I uploaded? Or do you mean that an analogue source should display more noise, even in a quiet section?

I'm confused.
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  #11  
Old 2006-08-16, 03:52 PM
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range_hood range_hood is offline
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Re: Are these tracks lossy?

I'm sorry, I should've read the thread more careful.

In your sample the area above 18kHz looks almost white. An unaltered analogue source should show more grey and not that steep drop in frequency response.
How could this happen?
A lossy codec (f.e. atrac 3+),
a digital low pass filter/noise reduction,
by altering the tone pitch of the recording in a digital way. Maybe the one who transferred it, ran the vinyl too fast and someone corrected it afterwards on the computer.
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  #12  
Old 2006-08-16, 04:40 PM
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Re: Are these tracks lossy?

Quote:
Originally Posted by range_hood
by altering the tone pitch of the recording in a digital way. Maybe the one who transferred it, ran the vinyl too fast and someone corrected it afterwards on the computer.
that's what I was thinking

I can't see any blocky shapes in it, just the sudden dropoff at 18kHz, so imo it is lossless.
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  #13  
Old 2006-08-23, 06:44 PM
alfienoakes101
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Re: Are these tracks lossy?

Thank you!
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