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Topic: Really lossless? (Read 7391 times) previous topic - next topic
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Really lossless?

Hey,

I got this APE file on my computer, and wanted to check if it really was lossless. So I decoded it and made a graph in EAC, here's what i got:



Thanks in advance for your help
how much is the fish?

Really lossless?

Reply #1 –
It seems to be from a lossy source, especially looking towards the beginning and end of the file where the sound isn't as complex and the lowpass is higher. I'm not a programming or psychoacoustic expert or anything, but it really does look like a lossy source.
Acid8000 aka. PhilDEE

Really lossless?

Reply #2 –
Simple answer: Mokeys Audio is lossless!

Really lossless?

Reply #4 –
Quote
Simple answer: Mokeys Audio is lossless!
[a href="index.php?act=findpost&pid=300848"][{POST_SNAPBACK}][/a]


I think you misunderstood me.    Off course Monkey's Audio is lossless, but the source file which was encoded with Monkey's Audio could possibly not be the original CD, but a lossy file like an mp3.

Maybe the topic title wasn't totally adequate 
how much is the fish?

Really lossless?

Reply #5 –
The source was definately lossly: There are "holes" for a lack of a better term in the spectrum around ~8 kHz after the 10 second mark where the encoder left out some of the audio because it was relatively quiet and would have been masked by the rest of the sound present.

Really lossless?

Reply #6 –
Looks like a lossy source.  Here's my spectrum straight from the WavPack:

Really lossless?

Reply #7 –
Quote
It seems to be from a lossy source, especially looking towards the beginning and end of the file where the sound isn't as complex and the lowpass is higher. I'm not a programming or psychoacoustic expert or anything, but it really does look like a lossy source.
[a href="index.php?act=findpost&pid=300847"][{POST_SNAPBACK}][/a]



Quote
The source was definately lossly: There are "holes" for a lack of a better term in the spectrum around ~8 kHz after the 10 second mark where the encoder left out some of the audio because it was relatively quiet and would have been masked by the rest of the sound present.
[a href="index.php?act=findpost&pid=300854"][{POST_SNAPBACK}][/a]


Thanks, you both have convinced me.

Too bad though I transferred 300megs of decompressed mp3 or such 
how much is the fish?

Really lossless?

Reply #8 –
Quote
Looks like a lossy source.  Here's my spectrum straight from the WavPack:


[a href="index.php?act=findpost&pid=300856"][{POST_SNAPBACK}][/a]


Hmm, same track and same artist i presume...?
how much is the fish?

Really lossless?

Reply #9 –
I think. Norah Jones - Feels Like Home - 01 - Sunrise (my guess, at least, from the title of the EAC window)

Really lossless?

Reply #11 –
Also with the lowpass being higher in parts where the sound should be less complex (ie. the beginning and end of the file) I'd assume its from a CBR lossy source.
Acid8000 aka. PhilDEE

Really lossless?

Reply #12 –
Quote
I think you misunderstood me.    Off course Monkey's Audio is lossless, but the source file which was encoded with Monkey's Audio could possibly not be the original CD, but a lossy file like an mp3.

Sorry, I misunderstood this part of your post (which imo is very misunderstandable)!
Quote
I got this APE file on my computer, and wanted to check if it really was lossless.

Really lossless?

Reply #13 –
Don't trust P2P, buy the CD. 
daefeatures.co.uk

Really lossless?

Reply #14 –
...and hope that the CD doesn't suffer from other flaws such as low dynamic range and the like. But yes, CDs indeed do win.
Acid8000 aka. PhilDEE

Really lossless?

Reply #15 –
Quote
I use auCDtect.exe to detect if a file is from the original source:
ftp://tta.iszf.irk.ru/aucdtect-lastest.zip
[a href="index.php?act=findpost&pid=300866"][{POST_SNAPBACK}][/a]


It's a very unreliable program and I wouldn't trust it too much. I've read many posts elsewhere where people have tested it extensively and got a lot of false negatives or false positives.

Really lossless?

Reply #16 –
I think that identifying between a lossy and lossless source is an action the human brain will always be superior in comparison with any computer algorithm. Well, that is, providing there is some aid, such as a spectrum analysis.
Acid8000 aka. PhilDEE

Really lossless?

Reply #17 –
Quote
I think. Norah Jones - Feels Like Home - 01 - Sunrise (my guess, at least, from the title of the EAC window)
[a href="index.php?act=findpost&pid=300859"][{POST_SNAPBACK}][/a]

yup
Quote
Quote
I think you misunderstood me.    Off course Monkey's Audio is lossless, but the source file which was encoded with Monkey's Audio could possibly not be the original CD, but a lossy file like an mp3.

Sorry, I misunderstood this part of your post (which imo is very misunderstandable)!
Quote
I got this APE file on my computer, and wanted to check if it really was lossless.

[a href="index.php?act=findpost&pid=300875"][{POST_SNAPBACK}][/a]

i agree
Quote
Don't trust P2P, buy the CD. 
[a href="index.php?act=findpost&pid=300878"][{POST_SNAPBACK}][/a]

i should 
Quote
I think that identifying between a lossy and lossless source is an action the human brain will always be superior in comparison with any computer algorithm. Well, that is, providing there is some aid, such as a spectrum analysis.
[a href="index.php?act=findpost&pid=300885"][{POST_SNAPBACK}][/a]

i agree, although i needed some help
how much is the fish?

Really lossless?

Reply #18 –
Quote
Quote
I use auCDtect.exe to detect if a file is from the original source:
ftp://tta.iszf.irk.ru/aucdtect-lastest.zip
[a href="index.php?act=findpost&pid=300866"][{POST_SNAPBACK}][/a]


It's a very unreliable program and I wouldn't trust it too much. I've read many posts elsewhere where people have tested it extensively and got a lot of false negatives or false positives.
[a href="index.php?act=findpost&pid=300884"][{POST_SNAPBACK}][/a]


In my experience it is very reliable if you analyse a whole cd.
You can group a track by track rip using -d.

Really lossless?

Reply #19 –
Quote
Quote
Quote
I use auCDtect.exe to detect if a file is from the original source:
ftp://tta.iszf.irk.ru/aucdtect-lastest.zip
[a href="index.php?act=findpost&pid=300866"][{POST_SNAPBACK}][/a]


It's a very unreliable program and I wouldn't trust it too much. I've read many posts elsewhere where people have tested it extensively and got a lot of false negatives or false positives.
[a href="index.php?act=findpost&pid=300884"][{POST_SNAPBACK}][/a]


In my experience it is very reliable if you analyse a whole cd.
You can group a track by track rip using -d.
[a href="index.php?act=findpost&pid=300889"][{POST_SNAPBACK}][/a]

I disagree. I've posted some examples somewhere here in this forum...one problem I had was that the original wav file got a probability of 90% whether the lossly LAME encoded file got 95% 

So it is not just that it identified a lossy LAME file as "CD" but also that the original file got a lower rating than the lossy file...
--alt-presets are there for a reason! These other switches DO NOT work better than it, trust me on this.
LAME + Joint Stereo doesn't destroy 'Stereo'

Really lossless?

Reply #20 –
Cant that be from a MD recording?
Alguém pare o mundo que eu quero descer!!

Really lossless?

Reply #21 –
I'd say that's most definitely an MP3 encoding; the behavior of the spectrogram at and above 16kHz is a giveaway for MP3's so-called "sfb21 limitation." Look at the spectra around 16kHz - there's an obvious difference in the amount of information just above and below that frequency. Below, there is a lot of signal/noise present, and above, there is just a few spikes of what may be louder, more sudden attacks. This looks much like what happens when one uses the -Y switch on LAME, or feeds a signal to an MP3 encoder that doesn't lowpass at bitrates like 192kbps.

Just an educated guess, of course.
 

Really lossless?

Reply #22 –
Quote
Cant that be from a MD recording?
[a href="index.php?act=findpost&pid=301859"][{POST_SNAPBACK}][/a]


From my past experience with MD, no. Before I got rid of my last MD recorder last year, I remember studying some of the signals in a spectrogram. For one thing, the most recent version of ATRAC doesn't lowpass at all - some signals are present past 21kHz, in fact. Plus, ATRAC is much more "spikey" looking, with lots of holes going all the way to the lower frequencies. Again, the smooth lowpass at 16kHz with occasional spikes of HF material makes me think that we are looking at an MP3 encoding, but without the original file that was (probably) used to make the first poster's lossless file, it's just speculation.