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Topic: is this a lossless file? (Read 9889 times) previous topic - next topic
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is this a lossless file?

hi, i recently purchased a few tracks from a website in wav format. i noticed when playing one of the files in foobar2000 that there was a black bar in the spectral display. i then inserted a combination of 'center cut' and 'cut sides' dsp filter in foobar and could blatantly hear artifacts of either mp3 compression or noise reduction --- that glassy high pitched compression/reduction sound. i opened the file in adobe audition and took a snapshot of it's spectral display. i'm not very experienced in interpreting spectral displays, so i thought i would post it and see if anyone here has an opinion. additionally, auCDtect reports the file as mpeg with a probability of %95.

the musical source itself is pretty lo-fi, likely produced on vintage digital gear.

purchased wav:


interestingly, below is a 192 mp3 file i downloaded elsewhere of the same track.

downloaded mp3:

is this a lossless file?

Reply #2 –
Quote from: greynol on
You'll need to zoom in on a transient event to be more certain, though it does appear to be lossy-sourced.


thanx, i zoomed in a bit on a section. below is a display of a distorted cymbal followed by a guy speaking. im not sure what to be looking for though... perhaps it is beyond the scope of this post.

zoomed in:


from looking at the above i thought maybe the limitations of the source possibly cut everything above ~15khz, so i decided to apply a 12k cut and record the signal in another audio card (digidesign > echo mia).

zoomed in w/ 12k cut:


its really not a huge deal... but i'd like to know if this website is sourcing some of their lossless from lossy.

is this a lossless file?

Reply #3 –
I'm looking for obvious holes in the spectrum near a transient event.  You'll need to zoom in more, but not just in time, but frequency as well.

By transient event I mean something like a drum hit.  Whether it is an area with obvious audible distortion does not matter. 

Recording the signal with another card is not a good idea.

is this a lossless file?

Reply #4 –
Quote from: systmcrsh on
purchased wav:

This spectrum is typical for encoding into “Mp3 CBR 96 kbit/s” (abrupt cut-off at 15 kHz).
You may try it by encoding a full-range (22 kHz or not less than 20 kHz bandwidth) file into “Mp3 CBR 96 kbit/s” and viewing its spectrum in Audition spectrum analyzer.
Quote from: systmcrsh on
interestingly, below is a 192 mp3 file i downloaded elsewhere of the same track.
downloaded mp3:

Such a spectrum is typical for encoding into “Mp3 CBR 192 kbit/s” (abrupt cut-off at 18,7 kHz).
You may also verify it by encoding a full-range (22 kHz or not less than 20 kHz bandwidth) file into “Mp3 CBR 192 kbit/s” and viewing its spectrum in Audition spectrum analyzer.

is this a lossless file?

Reply #5 –
Quote from: systmcrsh on
the musical source itself is pretty lo-fi, likely produced on vintage digital gear.

It is possible that we're seeing limitations of the original recording equipment. There were some early digital audio systems with 32 kHz sample rate and/or trick anti-aliasing filters and that could explain the 16 kHz cutoff. The content above 16 kHz during the louder sections may be distortion due to dynamic range compression introduced when the material was remastered.

I'm curious. What exactly are you listening to?

is this a lossless file?

Reply #6 –
Quote from: Notat on
Quote from: systmcrsh on
the musical source itself is pretty lo-fi, likely produced on vintage digital gear.

It is possible that we're seeing limitations of the original recording equipment. There were some early digital audio systems with 32 kHz sample rate and/or trick anti-aliasing filters and that could explain the 16 kHz cutoff. The content above 16 kHz during the louder sections may be distortion due to dynamic range compression introduced when the material was remastered.

But where, in case of probable such original recording, the 18,7 kHz in the “Mp3-192” file come from?

is this a lossless file?

Reply #7 –
Good point. The story I made up does not offer an explanation for that. That's a lot of very high frequency content in the MP3. Doesn't look Lo-fi to me.

is this a lossless file?

Reply #8 –
hi, thanx for the response. it may be impossible to tell because the original music source is so lofi. i decided to attach some examples if you are interested:

an excerpt of the lossless file purchased, track1: https://download.yousendit.com/MVNmRE9wbWdYSHlGa1E9PQ

an excerpt of the lossless file purchased, track2: https://download.yousendit.com/MVNmRE9xa0RwaFRIRGc9PQ

an excerpt of a 192k mp3 i downloaded from p2p, decoded with lame, track1-mp3: https://download.yousendit.com/MVNmRE9xa0Q3bUJMWEE9PQ

an excerpt of a 192k mp3 i downloaded from p2p, decoded with lame, track2-mp3: https://download.yousendit.com/MVNmRE9saTE1aVlLSkE9PQ

it definitely isnt audiophile material... but i was amused by how much better the 192k mp3 sounded. i should also point out that the mp3s and the lossless files are not sourced from the same material... both are likely sourced from different vinyls, or in the case of the lossless file, a master (but i doubt it).

like i said above... initially i became curious because of the sharp cutoff in the spectrometer in foobar2000. i then applied a "Center Cut - Cut Sides" dsp to the file in foobar using this plugin during playback: http://www.moitah.net/download/latest/foo_dsp_centercut.zip

and that's when i could blatantly hear all kinds of glassy artifacts... whether those artifacts are from noise reducing the source, or from mp3 compression, i don't know.

is this a lossless file?

Reply #10 –
Quote from: systmcrsh on
but i was amused by how much better the 192k mp3 sounded. i should also point out that the mp3s and the lossless files are not sourced from the same material... both are likely sourced from different vinyls, or in the case of the lossless file, a master (but i doubt it).

The mp3 is louder, that's why it sounds better to you. I speculate that everything from 16 to 20K is distortion (clipping). The mp3 has more distortion because it is cranked higher and clipped harder.

None of this has much to do with whether the material was originally coded or not.

Listening to differences between left and right channels is one technique used to highlight coding artifacts. That's what the center-cut plugin does. The fact that you're hearing funny stuff there is good evidence that there has been coding.

is this a lossless file?

Reply #11 –
It is clear to me from the two samples you uploaded that both of these purchased tracks had undergone a lossy process.

I determined this by doing exactly what I suggested you do in my previous post (zoom in both time and frequency and look for obvious holes in the spectrum).