I'm a newby here.
Seems like much studies have been made on the CPU performance and conversion accuracy of different lossless formats, but haven't heard much on the sound quality when they are played back. Bottom line, so what if one format has better CPU performance and conversion accuracy, if it doesn't duplicate the original CD sound. I believe that the theory behind lossless is decoding the file back to the original WAV/AIFF file. Hence, it should sound identical to CD. I say that this not the case in the real world.

I have compared Apple lossless with their counterpart AIFF using iTunes and CDs played directly through a cheap Technique CD player. Apple lossless doesn't sound as good as AIFF/CD. I couldn't distinguish between AIFF and CD, but Apple lossless suffers slight loss of bass and clarity at the low end. To me, it produces a muddier lows and mid-lows, producing boxier sound. BTW, the testing was done with decent equipment: M-Audio Firewire 410 interfaced to Mac G4 Dual and Crown amp output to Polk SDA speakers (old, but still good). The louder I played, more noticeable the differences become. This is not just my opinion. Others have said the same.

Have people compared different formats played through quality Hi-Fi equipment? And what's the verdict? Do I have supersensitve ears or lossless formats in fact produce tainted sound?

Hello, and welcome to Hydrogenaudio.

You are reading this because you violated forum rule number 8. Don't worry - you probably didn't know about it, or didn't understand the implications, and we understand that. The Hydrogenaudio Terms Of Service are here:

http://www.hydrogenaudio.org/forums/index.php?showtopic=3974

The gist of rule #8 is that if you make a claim, you must have proper supporting evidence for it. This rule is the very core of Hydrogenaudio, so it is very important that you follow it.

This is a generic post, and not all what follows may be applicable to this situation. Read through it nevertheless, it contains essential information and will help you understand what to do (or not to do).

Why should I bother with all of this, I just want to report a problem?

For audio quality matters, 'proper supporting evidence' is a blind listening test result demonstrating that you can hear a difference, together with a test sample. Graphs, non-blind tests, subtracting two files and so on are definetely not!

A proper blind test serves several purposes: it shows that you are serious towards our community, it proves to yourself that you can indeed hear a difference, it provides an indication of the seriousness of the issue at hand, and it helps pinpointing the problem for differnent listeners.

The easiest and most common way to do a blind test is an ABX test. There are several free utilities to do one:

http://www.pcabx.com/
http://ff123.net/abchr/abchr.html
http://www.rarewares.org/files/others/abchr-java.zip
http://www.kikeg.arrakis.es/winabx/winabx.zip
http://www.beryllium.net/~remco/linabx/

An ABX test requires you do identify an unknown (X) sample as either the original (A) or the processed (B) sample. With some statistics it can be figured out how likely it is that you were actually hearing a difference instead of just guessing which was which. Hydrogenaudio uses as a general guideline that < 5% change of guessing is considered 'proof' that you are hearing a difference. If you try the ABX test multiple tests, add up all attempts. You can use http://www.ff123.net/abx/abx.html to calculate the p-value ( < 5% = < 0.05), though most ABX programs have it built in.

If you managed to get a significant score, congratulations, it seems that the problem is real.

If applicable, you'll need to upload the test clip you used so other people can verify it and developers can tinker with it.

Uploading copyrighted music is generally illegal, but fair use laws generally permit short clips (< 30 secs) to be used for purposes such as this. Compress it with a lossless encoder (e.g. FLAC http://flac.sf.net) and upload it to either your own webspace or Hydrogenaudio's Uploads Section.

If you finally make your post to Hydrogenaudio, try to include as much information as is relevant, and be sure to explain exactly what and where (important but often forgotten) you hear the problem best.

Audio is to a large extent a subjective matter, and as such, quality matters are prone to a few problems. The first is listener preferences. Something that applies to you may not apply to the majority of people. Maybe the clip is an exception or problem case and not representative of general performance. This is why being able to verify a result is imporant, as well as giving the developers something concrete to work with.

The second is the mind. The human mind is powerfull, but has some weaknesses. It is very vulnerable to suggestion and subconscious influences, even for people experienced in these tests. No matter how how 'sure' you are that a problem exists, verify that it's not your mind playing tricks on you first, it'll save embarassement later.

'Simply' reporting a problem generally doesn't tell us anything, isn't indicative of anything, can be impossible to reproduce, confuses people, and most importantly, wastes precious developer time determining if the problem is real and serious or not.

You may have saved yourself 5 minutes, but you've cost other people an hour. That's not very nice.

A more detailed introduction to ABX tests has been written by Pio2001 here

Mea culpa.
Rule 8 seems pretty complex and time consuming. So I won't be able to do this. But let me rephrase my earlier forum without making any "claim". By previous comments were merely my opinion.

Seems like much studies have been made on the CPU performance and conversion accuracy of different lossless formats, but haven't heard much on the sound quality when they are played back. The theory behind lossless is decoding the file back to the original WAV/AIFF file, right? Hence, it theoretically should sound identical to CD. But how is it in the real world?

Have people compared different formats played through quality Hi-Fi equipment? And what's your opinion? I'm not asking for your proof or verification, just your opinion based on your observation.

And what do you recommend for lossless format? I prefer Mac OS.

Which part of "lossless" word you do not understand ?

It is pretty simple.
If you cannot decode back to the same exact* file it is not lossless.
There is no need for listening tests to figure out if something is lossless. You can just compare the files bit by bit.


*The whole file might not be bit identical due to difference in the headers but the audio data itself will be. Use something like EAC's or foobar's "compare" tool that only compares the audio data itself.

Perhaps this thread will help.

So you would rather have opinions instead of facts?

You would do well to search. Many people prefer FLAC and it is one of the most supported lossless codecs.

But on Mac OS, Apple Lossless is much better supported.

Sort of a mixed situation. Rule 8 specifically applies to subjective claims. Comparing lossless compressions can be done objectively by the means prohibited in the above clip, but he *did* make a subjective judgement..

The input and output files are identical. The process is lossless.

If the lossless formats decoder was crap I imagine it could introduce some artifacts. Although that would make it no longer lossless. I dislike TOS#8 since I got a warning level because of it for something that I have yet to get a response about, although the rule is necassary. Avoid any topics around #8. So in this case, lossless formats will all sound exactly the same.

Have you played backed different "lossless" formats and you believe they all sound the same or are you just going by what's advertised as "lossless"?

I wouldn't challenge 7z if I were you, he has a great deal of knowledge...

Go away and quit wasting our time with newbie questions. Lossless is lossless, end of story.

Maybe iTunes screws up playback of Apple Lossless.

The audio data in lossless files is exactly the same as in the original file : it's exactly like a .zip or .rar file... Imagine that you zip a text file, and then uncompress it, would it suffer from "slight loss of bass"? That's nonesens.

The only thing that varies is in fact hardware : lossless files need more CPU power... but they need less hard drive access... And HD are much louder than CPU... Therefore lossless files sound even better than original ones when playedback

Strange idea that one file that is contains binarily exactly the same information as the other one could sound differently...

The zipped text file is a good example

Well, I see you decided to continue trolling rather than bothering to read and understand very informative replies you've got; or even to comply with forum rules. One more useless post / TOS #8 violation and you are out.

Playback of corrupted lossless files generally sounds much less pleasant than "slight loss of bass and clarity at the low end" he describes. Until he provides blind test results, he's most likely yet another victim of placebo effect, or a troll.

Wow. Tough crowd. Sorry to have wasted your precious time with my newbie comment/question.
So you all pretty much take the position that all lossless files, when decoded, are binarically identical to AIFF/WAV files originating from CDs.

You all have good life.

@oogywawa. No, the output AIFF/WAV from a decoded lossless file dont need to be identical to the source.
But the PCM stream inside it needs to be identical!

Ok, bye!

Yes we do... that's because - stay with me here... it is

LOSSLESS

As in... without loss and maybe this would be a good reading for you http://en.wikipedia.org/wiki/Lossless

I don't know about you, but I don't "take the position" that the earth is round, I know it...

Mmm-kay. A lossless codec compresses audio in such a way that it reproduces the original audio bit for bit. That means, the compressed file and the original are absolutely IDENTICAL, audio-wise. There is ABSOLUTELY no doubt about that. A codec is 100% lossless, or it's not. Period.

Your problem here is that you're comparing the sound quality of your computer and your standalone CD player. This has nothing to do with that. You're not even comparing apples and oranges here, you're comparing apples to apple-pie. An apple is always an apple, even though it can be cooked by more or less talented cooks. The exact same sound file may sound very differently on different hardware.

I'm having a very hard time trying to explain this to you, but I can't see what it is that you don't understand. Your comparison is equivalent to playing the exact same CD on both the computer and your CD player.

Good analogy about the apple/apple-pie, I'll have to remember that one =]

The original poster must be spending too much time in those high-end audio "salons".

Well, using more CPU means it puts out more heat, requiring a higher fan speed, which is certainly louder than a hard drive.



At least with my computer... I got a Western-Digital "Quiet Drive," I literally can't hear it. But my fan sounds like a jet engine. I can't wait until I upgrade the computer to modern specs.

Just for amusement value -
My old laptop (Compaq Evo N1015v) has a sound chip with noticeable noise patterns affected by CPU usage level (dynamically adjusted CPU clock; noise kicks in when CPU is running at full speed - 1.666GHz). If you find lossless setup that decodes slowly enough to keep the CPU running at max speed, "playback" of such file could indeed sound different. This integrated sound chip is so bad that I wouldn't use it for listening again anyway; people who care about listening experience should get appropiate hardware without obvious issues rather than look for software solutions that don't clash with their broken hardware.

Just out of curiosity: How do you know that? I bet someone told you... No first hand experience of moon flights or so, eh?

He probably just looked out from a high hill or mountain.

But it would have to be a pretty high hill or mountain, and the air at that altitude would be pretty thin. How could you be sure what you were seeing wasn't some hypoxia induced delusion?

That is indeed an intelligent answer my friend. Looking from there to the arching horizon should clear people up...

Moon

I dunno, looking out a telescope at all the other round planets tends to convince me. =D

That, and looking out an airplane window at 41,000 feet. You can just see the curvature of the horizon. I might add that that flight was also to Australia, a good halfway around the world from where I was living at the time.

I've noticed that when I move my mouse I hear a slight buzzing in the audio in my sound card. Not noticable when I'm listening to music, but you can hear it during silence.

That is indeed an intelligent answer my friend. Looking from there to the arching horizon should clear people up...

Moon
[/quote]

Hehe, well, it may be very clearing for the mind, but I doubt that you'd see much more of an arch from up there than from the base.

Of course, clever people can deduct the shape of the earth from lunar eclipses, but anyway.. That wasn't really the point.

Didn't the ancient Greeks (one of them anyway) even calculate the earth's diameter by comparing astronomical observations from different locations?



I had that on a computer.. It turned out the noise came from dirty power on the computers 12 volt socket powering the speakers. I got a separate 12 volt wall-wart supply for the speakers and the mouse buzz was vanquished.

Did anyone see WHAT MP3? It was a freebie additional mag that came with WHAT HIFI/CINEMA a few months back.

They made the exact same claims - that Apple lossless didn't sound as good as the original because "compression is compression" as they put it.

What they did was to rip a CD with iTunes to Apple Lossless, burn it back to a CDR and compare that CD with the original on some NAIM kit.

(ok, first they compared the sound of an unspecified soundcard to the NAIM CD player, but we'll ignore that)

Anyway, I emailed them explaining their testing was flawed but got no response.


Has anyone actually checked Apple Lossless is lossless, just to be sure?
We know FLAC does it's job correctly but that's irrelevant here.

Yes, I verified that Apple Lossless is indeed lossless. MD5 hash on input WAV and decoded WAV were identical.

<rant>On a related note, I had to install iTunes to perform this test... which caused anal leakage, projectile vomiting and nausea. How anyone can bear to use this software is beyond me.</rant>

I have been using iTunes for 6-7 months and its still working without a single problem!
Maybe its a user error.

I would love to use iTunes for Apple lossless, but they have to fix those annoying gaps between tracks. I can not understand the logic of playing a lossless file that puts a gap between every song. For me, that's worse than listening to WMA files (not the lossless ones).

How hard can it be to fix that in the decoder?

You do understand that the gap is not actually encoded in the file, but produced by a lame decoder, don't you?

It wasn't really a case of the software not functioning, but I find the interface absolutely horrid. And by interface, I mean every aspect of the program.

It's a problem with player design requiring playback to be stopped/restarted when changing tracks - that includes shutdown/restart of playback thread, reopening output device, etc; not with the decoder. If decoder itself was the problem, decoded files wouldn't be bit-identical anymore (which as JensRex's test shows, they are). As far as I am aware of, iTunes can't play non-compressed formats such as AIFF gaplessly either.
Since their software/hardware has this limitation, they also have no reason to implement gapless MP4/AAC handling in their encoder and decoder, because noone would notice the difference; but that's a separate issue.

That is why I asked how hard is it to fix the decoder, not the encoder. So technically, the problem is not with the decoder or the encoder, but a function of the software opening and closing the output device.

For me, the point is moot. I'm only concerned with the end result. The end result is that Apple lossless played through iTunes has a gap between every track. That is such a shame. It could be so much better.

I agree, but such is the case of many other software and hardware players. The overpriced iPod is an even worse example. 4th generation and still no gapless playback in a device that's supposed to play back music, and do it well? What the hell?

True, and I have come to accept that with the playback of lossy formats. Of course Foobar2000 is the exception. It's the high watermark for all other audio playback applications.

It's when we talk about playback of lossless formats that I absolutely can not accept anything but perfection. That's the whole point of using all that disc space for lossless files. It should sound exactly like the CD in every way.