Is There A Way Of Calculating A Ratio of Quality Lost (FLAC vs mp3C)?

[DMBprez]

Anyone have any idea what kind of quality you actually lose when converting from FLAC to 320kbps?

Just curious.


Thanks.

[acidjack]

Anyone have any idea what kind of quality you actually lose when converting from FLAC to 320kbps?

Just curious.


Thanks.

Good question. I have often been curious if there has been any empirical analysis of FLAC to maximum-quality VBR files (AAC or FLAC). I assume, perhaps wrong, that since archive.org uses VBR, it must be better, since it theoretically provides "smarter" compression.

[Scooter123]

Its imperceptable to my ears--@320kbs, even with the most critical music and my best speakers, Vandersteins + Vanderstein Sub-Woofer. 

[rastasean]

well maybe we need to ask what quality is lost going from wave to flac level 6 so we can understand what frequency range is lost going from flac level 6 to mp3 320kbps.


comparing two of the same audio files is probably nearly impossible for most people but what about comparing a raw photograph (as in the format, raw) to a very, very high quality jpeg. would we be able to distinguish the difference?

[Will_S]

well maybe we need to ask what quality is lost going from wave to flac level 6

None at all - that's the whole point of lossless compression, the original data is recreated 100% upon decompression, it is just stored in a more efficient format.

so we can understand what frequency range is lost going from flac level 6 to mp3 320kbps.

It's not a simple matter of a particular frequency range being lost.  What information gets lost is very much a function of the original source material and the particular encoder used.  320 kbps mp3 is not a sufficient description to know exactly what encoding steps were performed, different encoders make different "choices" about what information is ok to lose, after first stripping out "redundant" information that can be recreated perfectly by the decoder.

comparing two of the same audio files is probably nearly impossible for most people but what about comparing a raw photograph (as in the format, raw) to a very, very high quality jpeg. would we be able to distinguish the difference?

As you are probably aware, jpeg is a lossy compression scheme (like mp3).  An analogy to flac would be making a zip file of the raw image - the information is 100% preserved.  Beyond that I'm not sure how the comparison is relevant - a highly compressed mp3 is obviously audibly inferior to the original wav file, while a higher bit rate mp3 made with a better encoder may be audibly indistinguishable.  But analyzing it on a bit for bit level you'll be able to detect a difference, just like a pixel for pixel comparison of a raw and jpeg image.  There's no reason to expect a certain % reduction in file size via jpeg compression and the same % reduction via mp3 compression to have the same impact on how close the compressed file comes to reproducing the original, the compression algortithms and the information needing to be preserved are just too different.

[Will_S]

Anyone have any idea what kind of quality you actually lose when converting from FLAC to 320kbps?

How much "quality" is lost is entirely subjective.

How much "information" is lost, you might get a first approximation by comparing the bit rate of the resultant flac file (using the most complete, slowest to excute compression) to 320 kbps.  I.e. if the flac file had a final size that equated to 400 kbps, you might say the mp3 lost 20% of the nonredundant information.  Of course, that assumes that the FLAC process is 100% efficient at only leaving important information behind, and that the mp3 process is 100% efficient at removing all redundant information before it starts removing nonredundant information.  Neither is likely to be entirely true in practice.  But you will find that wav files containing less information (i.e. low peaks, so they don't use the full bit depth, or not much stereo separation, so there is a lot of redundancy between left and right that is more efficiently represented with a mid signal and a side signal that can be fully described with fewer bits since it has little dynamic range) compress into smaller flacs than ones with lots of dynamic range and lots of stereo information.

[DMBprez]

Alright, thanks for the information guys. 


Now: I want to throw a situation out there, kind of curious of the reactions around here:

You upload a tape online (etree, whatever).  Are you okay with people distributing in FLAC?  I feel like Archive's atmosphere has changed the entire trading community BIG TIME.  Curious on your guys takes on it.

I agree with Scott in that there is literally no audible difference when listening  to FLACs and 320 mp3.  What do you guys feel?

[OFOTD]

You upload a tape online (etree, whatever).  Are you okay with people distributing in FLAC?

I agree with Scott in that there is literally no audible difference when listening  to FLACs and 320 mp3.  What do you guys feel?

I think you'll find that FLAC is absolutely the preferred distribution container.

Audible differences?  Absolutely no question about it.        If you're comparing mp3's and FLAC's on cheap computer speakers or cheap ipod headphones then possibly and probably no.   But throw on a a good set of headphones or a decent playback system and you will without doubt be able to tell the difference.

[Will_S]

Audible differences?  Absolutely no question about it.        If you're comparing mp3's and FLAC's on cheap computer speakers or cheap ipod headphones then possibly and probably no.   But throw on a a good set of headphones or a decent playback system and you will without doubt be able to tell the difference.

This is definitely true for the standard 128 kbps dreck that marks most people's experience of MP3s.  But can you honestly say you are confident you can distinguish a well-encoded 320kbps file from the original source in a blind test?

[rhinowing]

forget mp3, what about a V0

[OFOTD]

Audible differences?  Absolutely no question about it.        If you're comparing mp3's and FLAC's on cheap computer speakers or cheap ipod headphones then possibly and probably no.   But throw on a a good set of headphones or a decent playback system and you will without doubt be able to tell the difference.

This is definitely true for the standard 128 kbps dreck that marks most people's experience of MP3s.  But can you honestly say you are confident you can distinguish a well-encoded 320kbps file from the original source in a blind test?

Yes I feel confident that I could on my own playback.  Without doubt.   Now again on cheap PC speakers or ipod headphones possibly not but otherwise I believe I can.

[boojum]

Just a short story about people who "know" they can distinguish MP3's from WAV files in a blind test.  A fellow over at EAC support had a Golden Ears friend who could definitely and beyond a doubt distinguish MP3's from WAV's and gladly accepted the opportunity to prove it.  So the tester played a series of recorded tracks and asked could he tell which was which. Of course!  And in no uncertain terms he proceeded to say "A" was this and "B" was that and so on.   When the test was over and the testee had finished with his opinions the tester revealed that all the tracks were MP3's, at 128kBps.  The testee never again spoke to the tester.

Moral of the story: do not be too sure until you have actually done the test,  "One test is worth a thousand opinions."

And, you may have missed this post above:


"Its imperceptable to my ears--@320kbs, even with the most critical music and my best speakers, Vandersteins + Vanderstein Sub-Woofer. "

[OFOTD]

So because two people couldn't hear the difference that means the rest of the world can't either?

boojum are you a skeptic about everything unless it's in a book somewhere?

[DMBprez]

Just a short story about people who "know" they can distinguish MP3's from WAV files in a blind test.  A fellow over at EAC support had a Golden Ears friend who could definitely and beyond a doubt distinguish MP3's from WAV's and gladly accepted the opportunity to prove it.  So the tester played a series of recorded tracks and asked could he tell which was which. Of course!  And in no uncertain terms he proceeded to say "A" was this and "B" was that and so on.   When the test was over and the testee had finished with his opinions the tester revealed that all the tracks were MP3's, at 128kBps.  The testee never again spoke to the tester.

Moral of the story: do not be too sure until you have actually done the test,  "One test is worth a thousand opinions."

And, you may have missed this post above:


"Its imperceptable to my ears--@320kbs, even with the most critical music and my best speakers, Vandersteins + Vanderstein Sub-Woofer. "

Hahahah, awesome.

[DMBprez]

So because two people couldn't hear the difference that means the rest of the world can't either?

boojum are you a skeptic about everything unless it's in a book somewhere?

I'm in no means doubting you, because I am most certainly not an audiophile.  But I am curious as to what differences there are?  As we talked about, when you convert the file, it destroys "unnecessary," data, so I'm curious what that does to the sound.


Again, I don't mean this in an attacking way.  I'm really just curious.