Posted by
Hemos
on from the learn-more-about-it dept.
bullitB writes "For fans of the world wide patent conspiracy's latest audio format, the latest double blind AAC encoder comparison test results are in. If nothing else, this suggests much of the complaints regarding the iTunes Music Store's lossyness might be unfounded."
Glad to see development on AAC's sound quality...especially on the free side with the vast improvement of the previously terrible quality of FAAC.
More 'useful' (although it would stir the pot a bit more) would be a comparison with the latest MP3 encoders. To stay within the AAC bubble in comparisons won't encourage people to convert (or to stay away).
Is anybody else in this subthread plagued by associations with the sound of a duck squawking "AFLAC!"?
-- Shop as usual. And avoid panic buying.
Lossy is lossy
by
Anonymous Coward
·
· Score: 5, Interesting
When will people realise that half the trouble with a lossy format is transcoding? Sure, AAC may sound high-quality when it's in its original format, but when you transcode it to MP3 for your MP3 player, the quality turns to shit. This is inevitably the case when dealing with lossy formats, and why I'd rather buy CDs and rip them to FLAC.
Re:iTMS music does NOT sound lossy
by
misterpies
·
· Score: 5, Informative
I can tell you're a medical student and not a doctor, because most doctors are much more realistic about the limits of their knowledge. "Scientific" limits on the capabilities of biological systems are often wrong because of some overlooked or unknown factor.
A famous example of this is that for many years scientists could not work out how bees could fly. Their wings were too small, muscles too weak and bodies too heavy. It turned out that bees were able to use previously unknown aerodynamic effects to generate more lift than our previous "knowledge" allowed. Another example is that many birds of prey have visual acuity better than the laws of optics, applied to their eyes, would seem to permit. It turned out that the visual signal processing in their brains is so advanced that birds can actually 'see' features that are below the resolution limit of their eyes.
Similarly, we shouldn't be too dogmatic about what humans can and cannot hear. MP3s (and presumably AACs) compress music by suppressing parts you "can't" hear, not because they're outside your range of hearing but because the brain, assuming those parts should be there, fills in for them even when they're absent.
But it may be that you can't hear something consciously but still tell that it's not there. For example, there was a news story a week or so back showing that people could somehow tell when a picture had changed by the removal of an item in it, even though consciously they could not explain what the difference was - it just 'felt different'.
So, if someone claims to be able to tell the difference between 1 128Kb AAC and a CD, test that claim in a double-blind experiment. Only when he fails the test can you say he was imagining things.
-- The author of this post asserts his moral rights.
Unfortunately...
by
lotsofno
·
· Score: 5, Informative
Winamp 5.02's encoder (which got a lot of help from hydrogenaudio's own Menno, a FAAD AAC-decoder developer/Ahead MPEG4 developer) wasn't included in the listening test because of a bug they found before testing.
Too bad, too. I would've loved to have seen how it compared.
As a physicist, I'd just like to draw everyone's attention to the error bars on these charts. For the majority of the tests, it's possible to draw a horizontal line through the 95% confidence intervals of nearly all the points.
Hence, the conclusions declaring clear winners/losers in these cases are invalid. If 99% confidence intervals were used (which gives a better statistical test), I feel that no clear winners or losers would be drawn.
Be careful with these sort of studies - even though the author has used confidence intervals, he has failed to use them to infer the proper conclusions.
That said, it's awfully nice to see error bars on this sort of website. Simple data points give such a false sense of precision, I find...
Re:Error bars
by
patman600
·
· Score: 5, Informative
As a high school senior in a Statistics AP class currently studying confidence intervals and hypothesis testing, I think you are missing something. At the beginning, he clearly states your point: "One codec can be said to rated better than another codec with 95% confidence if the bottom of its line segment is at or above the top of the competing codec's line segment." The author gives which one is in first place, but announces at the beginning the requirements for a clear winner. And the author seems to me to be requiring at least half an interval of difference to even say that, much of the time he says they are tied.
Re:I'm not a doctor, but I play one on television
by
Golias
·
· Score: 5, Informative
The parent to this post was modded down for being rude to the grandparent, I suppose... but the point was correct. "The Digital Sound," as we used to call it back in the 80s, turned out to be the result of poor D/A conversion, poor error correction, and amplification hardware that was tweaked to compensate the shortcomings of LPs. Like I mentioned on another audio-related thread last week, a $300 Rotel CD player connected to a modern high-end stereo will sound as good or better when compared to a $3000 air-suspended, laser-guided turntable. (Especially after the LP has been played a few dozen times.)
--
Information wants to be anthropomorphized.
Re:I'm not a doctor, but I play one on television
by
Golias
·
· Score: 5, Insightful
I used to think the same way as your friend, because in the 80s and early 90s there did not seem to be any chance that digital sources could sound as good as my favorite LPs.
Then I heard what good CD players can sound like, and realized that the harshness of CD audio had nothing to do with resolution, and everything to do with component makers cutting corners. Your friend might make the same discovery, if he goes to a good listening room with an open mind.
--
Information wants to be anthropomorphized.
Re:Audiophile opinion
by
Amiga+Lover
·
· Score: 5, Insightful
Oh there's definitely a difference in pure analogue vs cd quality vs lossy compression codecs. Just taking a compression ratio down to 96kbit will make most listeners wince when their favourite tracks are played
I think that's part of it for many people. We might not hear parts of the music just like we may not "see" parts of a video clip on the first run round, but after 3 years listening to Louis Armstrong direct from CD, hearing him on 128kbit MP3 can be harsh. Humans learn and learn well, and the repitition of that playing guarantees we'll hear things that we're not meant to! or rather, things that we don't need to in order to identify a particular artist and recording. But we don't just listen to something to identify it, we listen to enjoy. That's different.
Most of the time 128kbit is fine for me. 192kbit for the things I'm familiar with.
As soon as you find someone who starts talking to you about directional audio cables, you must do two things: discount anything else they have ever said to you, and laugh in their faces. While it may seem, to the uninformed, that music 'flows' from the CD / record player out to the speakers, we must always remember that speakers are AC. Alternating current is required to make the speaker cones move in and out.
The real problem is that with all that back and forth motion, the electrons can get very very tired. I recommend that everyone with directional cables should only play their scratchy old LPs for a few minutes each day, lest the electrons in their very expensive cables succumb to extreme fatigue. Come to think of it, the Golden Ear crowd better buy replacements for all their cables once a month -- just in case!
--
Mike van Lammeren It will challenge your head, your brain, and your mind.
Re:iTMS music does NOT sound lossy
by
mhoward736
·
· Score: 5, Insightful
Bollocks! BUT...
If I listen to an MP3 or AAC file on my computer with its sound card and speakers (SB Audigy, Boston Accoustics) I can tell the difference between the same (160kbs) MP3 file and a (128k) AAC - the AAC sounds better. I can't tell the difference between the AAC and a WAV file however.
If I move up to my ($$$$) home stereo then I can easily tell the difference between the compressed and non-compressed versions of the same song. AAC still sounds better to me than MP3 however.
The difference here is money and environment, my office is a noisy place with all the computers etc running. My listening room is quiet and I spent a lot of time setting the stereo up so that its at its best.
I have not looked at OOG or any of the other formats so I can't comment on the relative merits of them.
Perspective
by
UnknowingFool
·
· Score: 5, Insightful
Not to quash anybody's personal opinion of AAC, there are a few things that we should note.
1) Most people can't tell the difference between formats that are similiar in performance.
2) Some people actually can tell the difference.
3) Some people are just posers who can't tell the difference but say they can.
4) Lastly, most people don't really care as long as it is convenient to use either format.
-- Well, there's spam egg sausage and spam, that's not got much spam in it.
Do you ask a car mechanic...
by
SnowDog74
·
· Score: 5, Insightful
For the chemical formula for internal combustion? No.
Likewise, I wouldn't go to the local audiophile shop to ask them about audio engineering-related issues.
After being accosted by about ten salespeople in ten minutes at a local audio store that sells everything from Sony ES, to Krell, Wadia, Sunfire and the like... I caught a sales rep in a bold-faced lie.
I was looking for a receiver without many bells and whistles, and he tried steering me towards Denon.
When I asked why Denon is "better", he replied, "Because they focus solely on making audio components unlike Sony."
I chuckled and asked him to explain to me the funadamental difference between the sample & hold buffers on a Sony DAC vs. a Denon DAC... Naturally, he had no clue what I was talking about.
The "double-blind" survey is somewhat misleading... but that being said, it's clearly not measuring which format is superlative... it's only measuring people's perceptions. And people were pretty much even on those various formats.
The study in question just shows that people cannot consistently tell the difference between AAC formats.
Now, I've read articles in audiophile magazines that insisted that SACD (Super Audio CD) was brilliant in comparison to CD. And every one of those articles was a load of crap.
Fundamentally, even the most "discriminating" audiophiles cannot tell the difference between 16-bit, 44.1kHz PCM (Pulse Code Modulation - e.g. AIFF, WAV, in the computer world) and the 1-bit, 2.7GHz DSD bitstream of SACD... nevermind the minute differences betweeen various AAC-enabled codecs.
Hell, I would challenge anyone to be able to tell the difference between 16-bit PCM and MPEG-4 AAC.
The AES (Audio Engineering Society) has stated that MPEG-4 AAC is perceptibly indistinguishable from uncompressed 16-bit, dual channel PCM (e.g. CD-DA spec audio).and I would wager any experienced audio engineer's pair of ears (my own included) against any consumer "audiophile" any day of the week.
My advice to the idle rich? Don't buy the $45,000 pair of speakers... instead buy yourself better hearing and some common sense.
My personal preference? MPEG-4 AAC. As a content creator intensely familiar with a variety of media standards including AES, NTSC, ISO, ITU-R/CCIR, etc. I believe MPEG-4 w/AAC (not Quicktime MPEG-4, mind you, but straight MPEG-4) is the superlative format for compressed audiovisual media.
However, for critical listening, only uncompressed audio is the way to go. The general rule of thumb is that higher bitrates are preferable over higher sampling frequencies. Frequency response roll-off is what you want to avoid. But in order to support the higher bitrates, you need a D/A Converter (DAC, Digital-to-Analog Converter) with an effective sample-hold buffer that can crunch the necessary data to make an accurate conversion of the digital source.
That being said, I'm going to begin digitally remastering my own compositions soon... and go straight from the 24-bit master to a 24-bit multichannel DVD-Audio format. Why? Even an audiophile deafened by the sound of their money burning a hole in their wallet can actually tell the difference between my 24-bit master recordings and the dithered 16-bit CD audio.
Re:You may have a point
by
BorgCopyeditor
·
· Score: 5, Informative
They may be pricks (or trolls), but they have some good points. If you can get past the annoying exterior, you might find some good information on these issues by googling for "audiophile" in rec.audio.pro, a group populated primarily by very good recording engineers. These are guys (mostly) who got where they are through both excellent (and aesthetically attuned) hearing and scientific knowledge of how audio works at every point in the signal chain. To watch them dismiss, with unimpeachable arguments and long experience, the claims of "sensitive" audiophiles can be instructive. I speak as one who has been schooled.
Slashdot Mirror
You can discuss this test with the author and others at http://www.hydrogenaudio.org
Glad to see development on AAC's sound quality...especially on the free side with the vast improvement of the previously terrible quality of FAAC. More 'useful' (although it would stir the pot a bit more) would be a comparison with the latest MP3 encoders. To stay within the AAC bubble in comparisons won't encourage people to convert (or to stay away).
I am Jack's witty signature line
When will people realise that half the trouble with a lossy format is transcoding? Sure, AAC may sound high-quality when it's in its original format, but when you transcode it to MP3 for your MP3 player, the quality turns to shit. This is inevitably the case when dealing with lossy formats, and why I'd rather buy CDs and rip them to FLAC.
I can tell you're a medical student and not a doctor, because most doctors are much more realistic about the limits of their knowledge. "Scientific" limits on the capabilities of biological systems are often wrong because of some overlooked or unknown factor.
A famous example of this is that for many years scientists could not work out how bees could fly. Their wings were too small, muscles too weak and bodies too heavy. It turned out that bees were able to use previously unknown aerodynamic effects to generate more lift than our previous "knowledge" allowed. Another example is that many birds of prey have visual acuity better than the laws of optics, applied to their eyes, would seem to permit. It turned out that the visual signal processing in their brains is so advanced that birds can actually 'see' features that are below the resolution limit of their eyes.
Similarly, we shouldn't be too dogmatic about what humans can and cannot hear. MP3s (and presumably AACs) compress music by suppressing parts you "can't" hear, not because they're outside your range of hearing but because the brain, assuming those parts should be there, fills in for them even when they're absent.
But it may be that you can't hear something consciously but still tell that it's not there.
For example, there was a news story a week or so back showing that people could somehow tell when a picture had changed by the removal of an item in it, even though consciously they could not explain what the difference was - it just 'felt different'.
So, if someone claims to be able to tell the difference between 1 128Kb AAC and a CD, test that claim in a double-blind experiment. Only when he fails the test can you say he was imagining things.
The author of this post asserts his moral rights.
Winamp 5.02's encoder (which got a lot of help from hydrogenaudio's own Menno, a FAAD AAC-decoder developer/Ahead MPEG4 developer) wasn't included in the listening test because of a bug they found before testing.
Too bad, too. I would've loved to have seen how it compared.
As a physicist, I'd just like to draw everyone's attention to the error bars on these charts. For the majority of the tests, it's possible to draw a horizontal line through the 95% confidence intervals of nearly all the points.
Hence, the conclusions declaring clear winners/losers in these cases are invalid. If 99% confidence intervals were used (which gives a better statistical test), I feel that no clear winners or losers would be drawn.
Be careful with these sort of studies - even though the author has used confidence intervals, he has failed to use them to infer the proper conclusions.
That said, it's awfully nice to see error bars on this sort of website. Simple data points give such a false sense of precision, I find...
The parent to this post was modded down for being rude to the grandparent, I suppose... but the point was correct. "The Digital Sound," as we used to call it back in the 80s, turned out to be the result of poor D/A conversion, poor error correction, and amplification hardware that was tweaked to compensate the shortcomings of LPs. Like I mentioned on another audio-related thread last week, a $300 Rotel CD player connected to a modern high-end stereo will sound as good or better when compared to a $3000 air-suspended, laser-guided turntable. (Especially after the LP has been played a few dozen times.)
Information wants to be anthropomorphized.
Then I heard what good CD players can sound like, and realized that the harshness of CD audio had nothing to do with resolution, and everything to do with component makers cutting corners. Your friend might make the same discovery, if he goes to a good listening room with an open mind.
Information wants to be anthropomorphized.
Oh there's definitely a difference in pure analogue vs cd quality vs lossy compression codecs. Just taking a compression ratio down to 96kbit will make most listeners wince when their favourite tracks are played
I think that's part of it for many people. We might not hear parts of the music just like we may not "see" parts of a video clip on the first run round, but after 3 years listening to Louis Armstrong direct from CD, hearing him on 128kbit MP3 can be harsh. Humans learn and learn well, and the repitition of that playing guarantees we'll hear things that we're not meant to! or rather, things that we don't need to in order to identify a particular artist and recording. But we don't just listen to something to identify it, we listen to enjoy. That's different.
Most of the time 128kbit is fine for me. 192kbit for the things I'm familiar with.
pay out the nose for single directional cable
Ha ha ha! I love the directional cable talk!
As soon as you find someone who starts talking to you about directional audio cables, you must do two things: discount anything else they have ever said to you, and laugh in their faces. While it may seem, to the uninformed, that music 'flows' from the CD / record player out to the speakers, we must always remember that speakers are AC. Alternating current is required to make the speaker cones move in and out.
The real problem is that with all that back and forth motion, the electrons can get very very tired. I recommend that everyone with directional cables should only play their scratchy old LPs for a few minutes each day, lest the electrons in their very expensive cables succumb to extreme fatigue. Come to think of it, the Golden Ear crowd better buy replacements for all their cables once a month -- just in case!
Mike van Lammeren
It will challenge your head, your brain, and your mind.
Bollocks! BUT...
If I listen to an MP3 or AAC file on my computer with its sound card and speakers (SB Audigy, Boston Accoustics) I can tell the difference between the same (160kbs) MP3 file and a (128k) AAC - the AAC sounds better. I can't tell the difference between the AAC and a WAV file however.
If I move up to my ($$$$) home stereo then I can easily tell the difference between the compressed and non-compressed versions of the same song. AAC still sounds better to me than MP3 however.
The difference here is money and environment, my office is a noisy place with all the computers etc running. My listening room is quiet and I spent a lot of time setting the stereo up so that its at its best.
I have not looked at OOG or any of the other formats so I can't comment on the relative merits of them.
1) Most people can't tell the difference between formats that are similiar in performance.
2) Some people actually can tell the difference.
3) Some people are just posers who can't tell the difference but say they can.
4) Lastly, most people don't really care as long as it is convenient to use either format.
Well, there's spam egg sausage and spam, that's not got much spam in it.
For the chemical formula for internal combustion? No. Likewise, I wouldn't go to the local audiophile shop to ask them about audio engineering-related issues. After being accosted by about ten salespeople in ten minutes at a local audio store that sells everything from Sony ES, to Krell, Wadia, Sunfire and the like... I caught a sales rep in a bold-faced lie. I was looking for a receiver without many bells and whistles, and he tried steering me towards Denon. When I asked why Denon is "better", he replied, "Because they focus solely on making audio components unlike Sony." I chuckled and asked him to explain to me the funadamental difference between the sample & hold buffers on a Sony DAC vs. a Denon DAC... Naturally, he had no clue what I was talking about. The "double-blind" survey is somewhat misleading... but that being said, it's clearly not measuring which format is superlative... it's only measuring people's perceptions. And people were pretty much even on those various formats. The study in question just shows that people cannot consistently tell the difference between AAC formats. Now, I've read articles in audiophile magazines that insisted that SACD (Super Audio CD) was brilliant in comparison to CD. And every one of those articles was a load of crap. Fundamentally, even the most "discriminating" audiophiles cannot tell the difference between 16-bit, 44.1kHz PCM (Pulse Code Modulation - e.g. AIFF, WAV, in the computer world) and the 1-bit, 2.7GHz DSD bitstream of SACD... nevermind the minute differences betweeen various AAC-enabled codecs. Hell, I would challenge anyone to be able to tell the difference between 16-bit PCM and MPEG-4 AAC. The AES (Audio Engineering Society) has stated that MPEG-4 AAC is perceptibly indistinguishable from uncompressed 16-bit, dual channel PCM (e.g. CD-DA spec audio).and I would wager any experienced audio engineer's pair of ears (my own included) against any consumer "audiophile" any day of the week. My advice to the idle rich? Don't buy the $45,000 pair of speakers... instead buy yourself better hearing and some common sense. My personal preference? MPEG-4 AAC. As a content creator intensely familiar with a variety of media standards including AES, NTSC, ISO, ITU-R/CCIR, etc. I believe MPEG-4 w/AAC (not Quicktime MPEG-4, mind you, but straight MPEG-4) is the superlative format for compressed audiovisual media. However, for critical listening, only uncompressed audio is the way to go. The general rule of thumb is that higher bitrates are preferable over higher sampling frequencies. Frequency response roll-off is what you want to avoid. But in order to support the higher bitrates, you need a D/A Converter (DAC, Digital-to-Analog Converter) with an effective sample-hold buffer that can crunch the necessary data to make an accurate conversion of the digital source. That being said, I'm going to begin digitally remastering my own compositions soon... and go straight from the 24-bit master to a 24-bit multichannel DVD-Audio format. Why? Even an audiophile deafened by the sound of their money burning a hole in their wallet can actually tell the difference between my 24-bit master recordings and the dithered 16-bit CD audio.
They may be pricks (or trolls), but they have some good points. If you can get past the annoying exterior, you might find some good information on these issues by googling for "audiophile" in rec.audio.pro, a group populated primarily by very good recording engineers. These are guys (mostly) who got where they are through both excellent (and aesthetically attuned) hearing and scientific knowledge of how audio works at every point in the signal chain. To watch them dismiss, with unimpeachable arguments and long experience, the claims of "sensitive" audiophiles can be instructive. I speak as one who has been schooled.
Shop as usual. And avoid panic buying.