I can hear a lot of the problems with my equipment. But, with some recordings, there isn't an audible difference. It depends upon the music.
It seems that most lossy codecs have an Achilles' heel or two, some particular sounds or sequences of sounds which they don't do well at, no matter how many bits you throw at the problem.
I don't consider myself particularly sensitive to these things, but a couple of years back I played with a test signal (a short segment of electronic music with some odd, buzzy-sounding synthesized notes (sawtooth waves, perhaps)) which some guy was claiming could be encoded much better with MP3 than AAC. At least with the MP3 and AAC encoders I tried at the time, he was right.
Maybe Apple has tweaked and tuned their AAC encoder since then to fix this one area of encoder weakness, but back then, it failed pretty badly on this particular bit of music. At 192 kbps, what I usually use, a very noticeable hiss was added to the background -- but only when these odd buzzy notes were playing. This was not a subtle, "gee, now I don't feel like I can tell what color shirt the singer is wearing anymore" change, but something I think most people would easily notice in a side-by-side comparison with the uncompressed original.
In this one case, even going to 256 kbps didn't help much -- the problem was still there, only reduced a little bit. Given that kind of thing can happen, I don't think it's too surprising that for some recordings, and portions of some recording, bit rate won't matter much. Simply that you've used compression at all will sometimes make a noticeable difference.
It seems that most lossy codecs have an Achilles' heel or two, some particular sounds or sequences of sounds which they don't do well at, no matter how many bits you throw at the problem.
I don't consider myself particularly sensitive to these things, but a couple of years back I played with a test signal (a short segment of electronic music with some odd, buzzy-sounding synthesized notes (sawtooth waves, perhaps)) which some guy was claiming could be encoded much better with MP3 than AAC. At least with the MP3 and AAC encoders I tried at the time, he was right.
Maybe Apple has tweaked and tuned their AAC encoder since then to fix this one area of encoder weakness, but back then, it failed pretty badly on this particular bit of music. At 192 kbps, what I usually use, a very noticeable hiss was added to the background -- but only when these odd buzzy notes were playing. This was not a subtle, "gee, now I don't feel like I can tell what color shirt the singer is wearing anymore" change, but something I think most people would easily notice in a side-by-side comparison with the uncompressed original.
In this one case, even going to 256 kbps didn't help much -- the problem was still there, only reduced a little bit. Given that kind of thing can happen, I don't think it's too surprising that for some recordings, and portions of some recording, bit rate won't matter much. Simply that you've used compression at all will sometimes make a noticeable difference.
What we have to remember about these codecs is that they are psychological in makeup. That is, they are taking things out that we are supposed not to be able to hear.
For the most part, they work well, but the lower the rate, the more must be taken out. At some point, we can begin to hear it.
Due to the nature of sampling, the higher frequencies have the fewest samples. Normally, this won't matter. The Nyquist formula works well. It has been proven many times over the years. It's used in all non compressed formats. But the compressed codecs remove even more samples from the high frequencies. If the music conforms to the psychological and auditory averages that are used for the codecs, all is well. But, if the music doesn't conform, then there could be an audible problem. These problems usually manifest themselves in those mentioned high frequencies first. Any signal with strong high frequencies will be affected the most. Electronic music, rock, with its high compression, etc.
The lower the sample rate, the earlier those problems appear, and the lower in the frequency range they appear. 128Kb/s is fine for most music, as long as it isn't listened to with wide band equipment. That is, a full audible frequency range with a good S/N ratio. $50 computer speakers and $10 headphones aren't likely to show any defects. But the better the equipment, the more likely they WILL show up.
I've found that AAC at 320Kb/s is generally pretty good, even on good equipment. But, even then, occasionally some distortion creeps in.
They should definitely just tweak their AAC encoder and offer 320 AAC versions of most stuff on iTMS for a bit more. And add the ability to play HE-AAC on the iPod, if we want to squeeze more stuff on there.
They should definitely just tweak their AAC encoder and offer 320 AAC versions of most stuff on iTMS for a bit more. And add the ability to play HE-AAC on the iPod, if we want to squeeze more stuff on there.
I thought the record companies provided the files on iTunes and that Apple themselves do not have lossless masters of everything to provide alternate formats.
I thought the record companies provided the files on iTunes and that Apple themselves do not have lossless masters of everything to provide alternate formats.
Steve
Correct. The record labels upload the encoded files to Apple. The bitrate, format, etc. decision is entirely up to the record labels, not Apple.
Correct. The record labels upload the encoded files to Apple. The bitrate, format, etc. decision is entirely up to the record labels, not Apple.
That's likely true, to a certain extent. but I think it's Apple that decided on the 128Kb/s.
Otherwise, with the competition between the labels, we should have seen a bitrate race, with one leapfroging the other to offer higher quality.
After all, it's no skin off their collective noses what Apple's problems are downloading higher bitrates, and it doesn't cost them any more to encode at them. All their masters are at least 16/44 anyway.
I always thought that humans could never hear above 20K Hz, and usually around 16K Hz or less, depending on how damaged your hearing is.
This is a very big argument in the audio community.
I agree with what you said. In fact, when you get older, you might not hear above 10K Hz.
But some people claim that we can "hear" up to 40K Hz. Their claims are meant to mean that somehow, get get it by bypassing our ear structure. No real evidence for this has ever been found.
But one reason for going higher in a Cd player, for example, is that the filter at the high end can be placed well above human hearing before it's brought back to the analog area, thus eliminating the downwards ringing that can occur with some filters.
Anyway, I'm against upscaling 16 44.1 to 24 96 because of non mathematically related artifacts created by the process.
If it's done, it should go to 88.2, thought there are still some problems with the increased bit-rate.
It's why some audiophiles "claim" to hear improved (different) sound from upscaling players. It's really artifacting. The same thing we get in Photoshop when we upscale in a non linear way.
Actually, the terms of the conversation have changed quite a bit, in that most new music sold on the iTMS today is AAC 256 without DRM, further blurring the distinction between CD quality and a lossy compression scheme.
Moreover, simply extending a three year old conversation with a new post that ignores the gap can be confusing and jarring for people looking at the thread-- I found myself becoming increasingly puzzled by the anachronistic claims being made until I thought to look at the posting dates.
Comments
Originally posted by melgross
I can hear a lot of the problems with my equipment. But, with some recordings, there isn't an audible difference. It depends upon the music.
It seems that most lossy codecs have an Achilles' heel or two, some particular sounds or sequences of sounds which they don't do well at, no matter how many bits you throw at the problem.
I don't consider myself particularly sensitive to these things, but a couple of years back I played with a test signal (a short segment of electronic music with some odd, buzzy-sounding synthesized notes (sawtooth waves, perhaps)) which some guy was claiming could be encoded much better with MP3 than AAC. At least with the MP3 and AAC encoders I tried at the time, he was right.
Maybe Apple has tweaked and tuned their AAC encoder since then to fix this one area of encoder weakness, but back then, it failed pretty badly on this particular bit of music. At 192 kbps, what I usually use, a very noticeable hiss was added to the background -- but only when these odd buzzy notes were playing. This was not a subtle, "gee, now I don't feel like I can tell what color shirt the singer is wearing anymore" change, but something I think most people would easily notice in a side-by-side comparison with the uncompressed original.
In this one case, even going to 256 kbps didn't help much -- the problem was still there, only reduced a little bit. Given that kind of thing can happen, I don't think it's too surprising that for some recordings, and portions of some recording, bit rate won't matter much. Simply that you've used compression at all will sometimes make a noticeable difference.
Originally posted by shetline
It seems that most lossy codecs have an Achilles' heel or two, some particular sounds or sequences of sounds which they don't do well at, no matter how many bits you throw at the problem.
I don't consider myself particularly sensitive to these things, but a couple of years back I played with a test signal (a short segment of electronic music with some odd, buzzy-sounding synthesized notes (sawtooth waves, perhaps)) which some guy was claiming could be encoded much better with MP3 than AAC. At least with the MP3 and AAC encoders I tried at the time, he was right.
Maybe Apple has tweaked and tuned their AAC encoder since then to fix this one area of encoder weakness, but back then, it failed pretty badly on this particular bit of music. At 192 kbps, what I usually use, a very noticeable hiss was added to the background -- but only when these odd buzzy notes were playing. This was not a subtle, "gee, now I don't feel like I can tell what color shirt the singer is wearing anymore" change, but something I think most people would easily notice in a side-by-side comparison with the uncompressed original.
In this one case, even going to 256 kbps didn't help much -- the problem was still there, only reduced a little bit. Given that kind of thing can happen, I don't think it's too surprising that for some recordings, and portions of some recording, bit rate won't matter much. Simply that you've used compression at all will sometimes make a noticeable difference.
What we have to remember about these codecs is that they are psychological in makeup. That is, they are taking things out that we are supposed not to be able to hear.
For the most part, they work well, but the lower the rate, the more must be taken out. At some point, we can begin to hear it.
Due to the nature of sampling, the higher frequencies have the fewest samples. Normally, this won't matter. The Nyquist formula works well. It has been proven many times over the years. It's used in all non compressed formats. But the compressed codecs remove even more samples from the high frequencies. If the music conforms to the psychological and auditory averages that are used for the codecs, all is well. But, if the music doesn't conform, then there could be an audible problem. These problems usually manifest themselves in those mentioned high frequencies first. Any signal with strong high frequencies will be affected the most. Electronic music, rock, with its high compression, etc.
The lower the sample rate, the earlier those problems appear, and the lower in the frequency range they appear. 128Kb/s is fine for most music, as long as it isn't listened to with wide band equipment. That is, a full audible frequency range with a good S/N ratio. $50 computer speakers and $10 headphones aren't likely to show any defects. But the better the equipment, the more likely they WILL show up.
I've found that AAC at 320Kb/s is generally pretty good, even on good equipment. But, even then, occasionally some distortion creeps in.
Originally posted by Aquatic
They should definitely just tweak their AAC encoder and offer 320 AAC versions of most stuff on iTMS for a bit more. And add the ability to play HE-AAC on the iPod, if we want to squeeze more stuff on there.
I thought the record companies provided the files on iTunes and that Apple themselves do not have lossless masters of everything to provide alternate formats.
Steve
Originally posted by demenas
I thought the record companies provided the files on iTunes and that Apple themselves do not have lossless masters of everything to provide alternate formats.
Steve
Correct. The record labels upload the encoded files to Apple. The bitrate, format, etc. decision is entirely up to the record labels, not Apple.
Originally posted by Chucker
Correct. The record labels upload the encoded files to Apple. The bitrate, format, etc. decision is entirely up to the record labels, not Apple.
That's likely true, to a certain extent. but I think it's Apple that decided on the 128Kb/s.
Otherwise, with the competition between the labels, we should have seen a bitrate race, with one leapfroging the other to offer higher quality.
After all, it's no skin off their collective noses what Apple's problems are downloading higher bitrates, and it doesn't cost them any more to encode at them. All their masters are at least 16/44 anyway.
Originally posted by Gene Clean
Nice to meet you. And it's AAC 128, not 256.
I'm aware the iTMS only sells 128kbps, my point stands regarding 256kpbs. I replied to a previous poster about lossy formats being bad quality.
I always thought that humans could never hear above 20K Hz, and usually around 16K Hz or less, depending on how damaged your hearing is.
This is a very big argument in the audio community.
I agree with what you said. In fact, when you get older, you might not hear above 10K Hz.
But some people claim that we can "hear" up to 40K Hz. Their claims are meant to mean that somehow, get get it by bypassing our ear structure. No real evidence for this has ever been found.
But one reason for going higher in a Cd player, for example, is that the filter at the high end can be placed well above human hearing before it's brought back to the analog area, thus eliminating the downwards ringing that can occur with some filters.
Anyway, I'm against upscaling 16 44.1 to 24 96 because of non mathematically related artifacts created by the process.
If it's done, it should go to 88.2, thought there are still some problems with the increased bit-rate.
It's why some audiophiles "claim" to hear improved (different) sound from upscaling players. It's really artifacting. The same thing we get in Photoshop when we upscale in a non linear way.
There it is- the post telling us how old the thread is.
So here's the post telling how irrevelent that post is. Sorry folks.
As if the thread no longer has any significance. Sorta the value of the written word, eh? It doesn't have to be immediate?
Get over it and yourself... Nobody said a damn thing about irrelevance. You read much into very few words.
Moreover, simply extending a three year old conversation with a new post that ignores the gap can be confusing and jarring for people looking at the thread-- I found myself becoming increasingly puzzled by the anachronistic claims being made until I thought to look at the posting dates.
I'm beginning to see what you were tryng to say.
I wish I could say the same.