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aaronk
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| Posted: 17 May 2010 at 11:36am | IP Logged
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Brian, I used the spectral analysis on all of the tracks, and it was obvious on "Lovegame" and "You Belong With Me." What was interesting is that "Best I Ever Had" and "Whatcha Say" looked okay on the spectral view, showing frequencies all the way to 24kHz. My ears were telling me different, though.
To confirm they were lossy sources, I used the "vocal cut" and I could hear all kinds of compression artifacts. I compared them with versions I had on Promo Only and Prime Cuts discs, and I could not detect any compression artifacts on those copies.
The logical conclusion is that those two particular tracks were not from mp3s, but rather they were compressed using some other file type. As Nick stated above, AAC files still keep all of the frequencies. But as you are probably well aware, Brian, if the bitrate is 256k, yet all of the frequencies are in tact, something else has been thrown away to keep the file size that small.
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Brian W.
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| Posted: 17 May 2010 at 1:00pm | IP Logged
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I'm sure you're correct; however, I do own some old CDs that peak out at around 20,000hz. My 1988 import CD single of "Hands to Heaven" by Breathe, for example, just cuts off everyting above 21,000hz.
Hands to Heaven spectral view
Edited by Brian W. on 17 May 2010 at 1:06pm
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eric_a
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| Posted: 17 May 2010 at 1:35pm | IP Logged
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Brian W. wrote:
I'm sure you're correct; however, I do own some old CDs that peak out at around 20,000hz. My 1988 import CD single of "Hands to Heaven" by Breathe, for example, just cuts off everyting above 21,000hz.
Hands to Heaven spectral view |
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That doesn't surprise me -- digital audio is capped at half the sampling rate. In other words, audio from a CD (44.1 kHz) would be limited to ~22 kHz. In fact, if I rip a CD, Adobe Audition limits the spectral view to exactly 22050 Hz.
But I think it's slightly more complicated in practice. I seem to remember learning in school about the Nyquist principles, that the audio frequency limit is *slightly lower* than half of the sampling rate. So 44.1 kHz was chosen because it was slightly more than double 20 kHz, the maximum audio frequency, at least at the time. Maybe as technology has improved, audio has crept up from 20k.
This has a good, brief explanation:
http://www.cs.columbia.edu/~hgs/audio/44.1.html
Edited by eric_a on 17 May 2010 at 1:35pm
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aaronk
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| Posted: 18 May 2010 at 7:12am | IP Logged
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Brian, I've seen several cases that look exactly like the picture you've posted, and they are not lossy sources. Thanks for bringing up a good point!
I won't claim to be an all-knowing guru of how this stuff works. (Eric, it looks like you probably know more than I do.) My earlier demonstration was how to spot an mp3 source visually. I haven't tested this with every lossy file type, but obviously there are some that span the full spectrum of frequencies but are still lossy.
I do know that many songs on CD don't cut off at 22kHz, as can be seen with "Run This Town" in the earlier example.
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aaronk
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| Posted: 20 May 2010 at 7:09am | IP Logged
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Just when I thought it couldn't get any worse, I received my Now 31 disc in the mail.
"Boom Boom Pow" (lossy)
"Right Round" (lossy)
"I Know You Want Me" (lossy)
"Blame It" (lossy)
"Day 'N' Nite" (lossy)
"Kiss Me Through The Phone" (lossy)
"Mad" (lossy)
"My Life Would Suck Without You" (lossy)
"That's Not My Name" (lossy)
"You Found Me" (lossy)
"If Today Was Your Last Day" (lossy)
More than half of the disc was mastered from mp3s or other lossy sources! I'm ticked...
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Brian W.
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| Posted: 20 May 2010 at 9:44am | IP Logged
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Hmm, I wonder if the single edit of "Chicken Fried" on the Grammy Nominees 2010 comp is from a lossy source:
Chicken Fried Spectral
I did run the whole disc through the Tau Analyzer, freeware that analyzes whether a CD is from a lossy source, and it did find that every track was from a lossless soure. But it doesn't claim to be 100% accurate. I've found it to be maybe 50% accurate, track by track, though I don't think it's ever said that a track that I knew was lossless was from a lossy source.
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aaronk
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| Posted: 20 May 2010 at 1:11pm | IP Logged
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Brian, that is definitely a lossy source, although the quality is probably pretty good. Did you try doing a "Vocal Cut" preview? That will often confirm if what you see is also what you hear.
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Todd Ireland
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| Posted: 20 May 2010 at 9:41pm | IP Logged
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aaronk wrote:
Just when I thought it couldn't get any worse, I received my Now 31 disc in the mail.
[snip]
More than half of the disc was mastered from mp3s or other lossy sources! I'm ticked... |
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I bought both the Now 31 and Now 32 discs, so I'm really ticked off to learn this too, Aaron! The main reason I still buy CDs is to get music in the best available lossless sound quality.
Geez, the major record labels keep finding new ways to self-destruct that it's no wonder why they're completely going down the tubes! It's bad enough that the industry too often packages new CD releases in cheap, flimsy, "green-friendly", cardboard packaging, but if they're now resorting to issuing new audio CDs with inferior lossy sound quality, then I'm done with buying current music on disc. I'd be no worse off just purchasing mp3s of each individual track on I-Tunes (although the Now discs contain many radio edits that unfortunately are not readily available on commercial CD releases).
Edited by Todd Ireland on 20 May 2010 at 9:43pm
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Nick2341
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| Posted: 21 May 2010 at 12:24pm | IP Logged
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From my limited experience dealing with A&R people, a lot of them send songs to DJs as MP3 from 192 - 320 Kbps and WAV through sites like You Send It or their own E-cards. This might be what they send to the Now people as well. So the person downloading the tracks might choose MP3 to save download bandwidth or they just don't know what the difference really is.
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aaronk
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| Posted: 21 May 2010 at 2:54pm | IP Logged
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Nick, based on your educated guess, the process would go something like this:
A&R Guy: "Hey, I just downloaded all the new popular songs off LimeWire and burned them on CD. Wanna hear it?"
Mastering Engineer: "Naw, just write 'Now 31 - Master Copy' on it with a Sharpie and leave it at my work station. I'll send it out this afternoon to have copies made."
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Todd Ireland
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| Posted: 22 May 2010 at 9:09am | IP Logged
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LOL That's funny, Aaron, but sadly probably not far from the truth.
I sometimes wonder if in the future record labels (assuming any still even exist) will call upon a highly reputable audio engineer like Steve Hoffman or Dennis Drake to remaster hits from the past 15 years in audiophile quality with no compression or frequency loss and a normal dynamic range?
No, I'm not holding my breath.
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Nick2341
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| Posted: 22 May 2010 at 12:15pm | IP Logged
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aaronk wrote:
Nick, based on your educated guess, the process would
go something like this:
A&R Guy: "Hey, I just downloaded all the new popular songs off LimeWire
and burned them on CD. Wanna hear it?"
Mastering Engineer: "Naw, just write 'Now 31 - Master Copy' on it with a
Sharpie and leave it at my work station. I'll send it out this afternoon to
have copies made." |
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Back in 2008 I asked Island for a promo to Janet's "Rock With U" and they
sent a CD-R labeled with a Sharpie. I e-mailed back and said I want the
final pressed CD. Like they didn't have any laying around or something.
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Brian W.
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| Posted: 22 May 2010 at 2:17pm | IP Logged
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As disturbing as this is, I will somewhat defend the AAC format. I'm certainly not defending its use on factory-pressed CDs, but for a lossy format, it is very impressive.
The variable bitrate option in Quicktime AAC (which is what iTunes uses) is quite amazing. I recnetly ripped George Michael's song "Faith" in iTunes Plus format (which, as covered earlier in the thread, is Quicktime AAC Constrained Variable Bitrate with a target bitrate of 256kb, at Quicktime's "Highest Quality" setting).
I was very surprised to see that, though the average bitrate was in the mid-200s, Foobar shows the PEAK bitrate during the opening guitar notes to be in the UPPER 400s. It's a fast running counter of the current bitrate, so I couldn't quickly seek out the peak bitrate of the song, but by pausing I was able to catch the bitrate up to 486kb at one point. Those acoustic guitar strums must be very complex to encode, as the bitrate didn't go that high anywhere else in the song.
There is a free encoder you can use with both Foobar and Exact Audio Copy (both freeware as well) called Quicktime AAC Encoder. http://tmkk.hp.infoseek.co.jp/qtaacenc/ It allows you to use the full features of Quicktime's AAC encoder (WITHOUT upgrading to Quicktime Pro).
With it, you can use the "True Variable Bitrate" and "Average Bitrate" settings of Quicktime's encoder, something iTunes does not give you the option to use. (Also, you can specify any bitrate at "highest" quality. Itunes does everything except iTunes Plus at "medium" quality.)
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Todd Ireland
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| Posted: 22 May 2010 at 6:34pm | IP Logged
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Is there a way to tell if any of the lossy tracks on the recent Now CDs were AAC encoded?
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Brian W.
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| Posted: 22 May 2010 at 9:41pm | IP Logged
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Well, if the bitrate never goes above 19,000hz, then it wasn't MP3. But there are other lossy codecs besides AAC.
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EdisonLite
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| Posted: 23 May 2010 at 10:19am | IP Logged
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Todd Ireland wrote:
I sometimes wonder if in the future record labels (assuming any still even exist) will call upon a highly reputable audio engineer like Steve Hoffman or Dennis Drake to remaster hits from the past 15 years in audiophile quality with no compression or frequency loss and a normal dynamic range?
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Sadly, this seems nearly impossible. The labels would need to have a 2-track stereo master that is UNMASTERED, and therefore, not compressed to death, lying around somewhere. Without that, the only other real option (to have a file that was never compressed to death in the first place) would be to take the multi-track and mix it again and simply never compress. But the new mix will most likely not be exactly the same (unless they saved the automation and settings involved for that mix). And no one really wants a new mix that's not quite what we heard on the radio.
Luckily, when recordings are compressed so drastically that my ears would bleed, I use a function on Wavelab software called "Uncompress". This would be the best option to do if you wanted a normal sounding (less compressed) WAV file. And still, we'll never really know if the new result is exactly what the song would sound like if it was never compressed in the first place. But still, I think it's a better option than having someone go in and do a brand new mix that does not match up to the old mix in every exact way.
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EdisonLite
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| Posted: 23 May 2010 at 10:23am | IP Logged
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BTW, I've been meaning to add that the messages in this "Lossy Sources" post have been fascinating to read. Aaron, those graphs you included that showed the difference between mp3s and WAVs (and the close-ups of those difference) were very enlightening.
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aaronk
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| Posted: 23 May 2010 at 12:39pm | IP Logged
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Thanks, EdisonLite! That means it was worth my time to post the info and screen shots :)
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aaronk
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| Posted: 23 May 2010 at 12:41pm | IP Logged
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Todd Ireland wrote:
| Is there a way to tell if any of the lossy tracks on the recent Now CDs were AAC encoded? |
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If it helps, I can hear the compression artifacts on almost all of the tracks. I've not yet had time to test out the AAC encoder to see how much better it sounds.
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Todd Ireland
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| Posted: 23 May 2010 at 7:11pm | IP Logged
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EdisonLite wrote:
| BTW, I've been meaning to add that the messages in this "Lossy Sources" post have been fascinating to read. Aaron, those graphs you included that showed the difference between mp3s and WAVs (and the close-ups of those difference) were very enlightening. |
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I'll second that... Excellent work on your tutorial, Aaron!
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Top 40 Music on Compact Disc : Chat Board
Topic: Lossy sources on big 2009 hits
