[LarryB]

Steve:

This is a follow-up to the discussion you and I had yesterday, which I hope will be informative for others as well.

I have heard mixed things about lossless codecs such as FLAC.  Some swear they are identical to uncompressed, whereas others feel they are sonically compromised.  Could you please share your views on this? And this time, since it will be written down, I won't have to ask again next week.

And while you're at it, please explain again why there can be problems with programs such as iTunes.  I was trying to explain it to a friend but would rather provide him with some actual information, rather than my stutterings.

Thanks!

Larry

[ted_b]

I'm also interested in your take on this "can lossless codecs sound differently" thing.  At CES I visited the Blue Smoke Black Box room (nice sound with those Rockport speakers) and they are putting together a very expensive ($7k, can't see the value, yet, really) heat-pipe solid state pc music server (doesn't include NAS, DAC or monitor) and recommend WMA lossless or WavPack, claiming FLAC is asynchronous and breathes or pumps during decoding (likely my poor explanation of their argument) ??

[LarryB]

Ted:

You and I got our information from the same place; I know Ron but had never before met Peter, who is the computer guru of Blue Smoke.

Let's see what Steve has to say.

Regards,

Larry

[audioengr]

I have personally limited experience with lossless CODEC's, but I can share some anecdotes from my customers (some who have done extensive experimentation and I trust their results) and my take on what must be happening. 

Here are the things that are a common thread:

1) Apple Lossless and FLAC both generate bit-perfect data after decompression, if you do a static file comparison.

2) Both CODEC's seem to behave less than perfectly with real-time playback at times.  Whether this is computer-dependent, OS dependent or player S/W dependent is yet to be determined.  Since the data is obviously not changed, the differences must be jitter.  Breathing and pumping is essentially a form of jitter.

New data also indicates the there is something fishy with iTunes ripping to Apple-Lossless.  The same track ripped with EAC on a PC and then translated to AL on a Mac can sound significantly better, radically different than the track ripped directly to AL with iTunes.

My friend that is doing these experiments is still in the throes of determining the exact process and mechanism behind this.  I would not be the least surprised if iTunes to AL ripping had a bug in it.

Steve N.

[LarryB]

Thanks.

[marked96]

Hi,
I have done a test with a local NAIM dealer about this last week:

We tested NAIM's cheapest CD player against an AppleTV connected to the NAIM SuperNait's build in DAC (which is supposed to be quite good, on par with NAIMs medium priced CD player). Much to my frustration the CD player sounded clearly much better than the AppleTV playing ALAC (Apple Lossless) files (all effects, volume, etc turned off - even screensaver).

I had already given up when the dealer insisted I convert one album from ALAC to AIFF and redo the test (at this point I argued this is pointless because all bits are there, tralala,... you know the arguments).

Voila: AIFF sounded better than ALAC. Still not as good as the CD player, but close.

I'm far from really knowing anything here - but it must be a matter of jitter's right?

Now you know why I'm hanging around here:)

Best
Mark

[audioengr]

Hi,
I have done a test with a local NAIM dealer about this last week:

We tested NAIM's cheapest CD player against an AppleTV connected to the NAIM SuperNait's build in DAC (which is supposed to be quite good, on par with NAIMs medium priced CD player). Much to my frustration the CD player sounded clearly much better than the AppleTV playing ALAC (Apple Lossless) files (all effects, volume, etc turned off - even screensaver).

I had already given up when the dealer insisted I convert one album from ALAC to AIFF and redo the test (at this point I argued this is pointless because all bits are there, tralala,... you know the arguments).

Voila: AIFF sounded better than ALAC. Still not as good as the CD player, but close.

I'm far from really knowing anything here - but it must be a matter of jitter's right?

Now you know why I'm hanging around here:)

Best
Mark

It's uncompressed format (AIFF) versus compressed format (ALAC) that you are hearing.

There is some kind of jitter going on when the lossless CODECs uncompress the data on-the-fly, even though they are bit-perfect.  Lossy CODEC's of course sound worse.

I recently discovered also that iTunes ripping to Apple Lossless is somehow broken.  The same file ripped with EAC and then converted to AL on a Mac sounds a lot better. Go figure?

BTW, I have customers with Apple TV's using the Pace-Car to reclock them.  Makes a big difference.  This would likely outperform the Transport that you tested.  No transport that I know of has jitter as low as the Pace-Car.  I have modded lots of them: 2 Philips, several Pioneers, several Sonys, Denon, Northstar, Ensemble, Vecteur and others.

Steve N.

[marked96]

Yes - I meant to say that I suppose jitter for ALAC decompressed files must be higher than for AIFF files. Unless the decoder is doing something criminal and really changing the bits.

Steve: you must have the hard/software needed to measure jitter. Why don't you shed some light into this?
I would really like to know how much jitter the AppleTV has for AIFF vs ALAC.

in fact I could not find any test about the AppleTV's jitter amount (only about the AirportExpress, measured by Stereophile).

Best
Mark

[audioengr]

Yes - I meant to say that I suppose jitter for ALAC decompressed files must be higher than for AIFF files. Unless the decoder is doing something criminal and really changing the bits.

Steve: you must have the hard/software needed to measure jitter. Why don't you shed some light into this?
I would really like to know how much jitter the AppleTV has for AIFF vs ALAC.

in fact I could not find any test about the AppleTV's jitter amount (only about the AirportExpress, measured by Stereophile).

Best
Mark

My customers have Apple TV's, but I dont have one so I cannot help you right now.

Steve N.

[firedog]

I find it interesting that none of the audio sites/publications have ever done a good blind listening test of FLAC vs uncompressed, since FLAC is extensively used among audiophiles.

My audiophile friends and I have done some casual blind testing. We've used EAC and dbpoweramp on 2 differnent PCs for ripping. Although each of us thinks we hear very slight differences between various rips, we can't consistently pick out which is which - another way of saying we're not sure one sounds better than the other.

The explanation might be something Steve is hinting at - not the files themselves, but the on the fly conversion. If there is a bit of jitter introduced by the conversion, it is probably something that can be eliminated over time with software and hardware improvements.

[WerTicus]

you also dont know if its a problem with the flac format or the hardware or software your using at the time. or a combination of these things, need to be more scientific with the testing.

[sleepysurf]

A very simple test is to compare FLAC and WAV files of the same material.  I have done so (Squeezebox into Benchmark DAC), and notice no discernable difference.

[WerTicus]

yes I've not heard any difference either.  However it wouldn't surprise me if certain sound cards or player software or drivers or even versions of windows had problems.

[krikor]

Ditto with my system comparing FLAC and AIFF files through a Squeezebox ... no significant differences, though if pressed I may even say FLAC had the edge.  I wonder if the fact that the Squeezebox handles the conversion natively, rather than at the computer end, has something to do with its ability to handle FLAC.  Perhaps it does a better job of decompressing the FLAC files and outputting less jitter as opposed to what the computer does, and without worries about sound card, player software and driver variables.  It is also well isolated from the nasties inside the computer being networked either wirelessly or via ethernet.

I have also compared the FLAC files via Squeezebox with the original CD, both going through my Cary 306/200.  CDs routinely have a minor edge, sounding a bit more open and smooth with better bass.  I would venture a guess that this is due to the SPDIF interface between the SB3 and Cary, while CDs are handled directly inside the Cary.  But the difference was not significant enough to give up the convenience of the Squeezebox... I love the ability to easily access, randomize and jump between selections.