File-based audio playback - compressed vs. uncompressed

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Originally Posted by synsei

Perhaps your ears aren't flapping at the right speed Bob, try upping the frequency to 128 flaps per second, that should get you sorted... :D

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My ears should be burning judging by the last response from the only one so far to raise the issue on this thread..... :rolleyes:
Neat trick on the flap frequency, and if it helped get to the bottom of this riddle, believe me I would try it.:steam: There, does that look like wings?

Daft though it sounds, it is intriguing what has been claimed. Despite being something that made no sense to me, I was open minded enough previously to investigate it, and found nothing with the variables available.:mental:
Maybe it existed, and I just didn't find it, but thereby it is not the universal truth that was stated. :eek:
Don't get me wrong, I don't want the problem, and don't experience the problem, but if it has a cause, it would be good to get to the bottom of it.....finally...;)
I had thought that this thread might help focus on and identify the claimed phenomenon once and for all but it seems to be intriguingly elusive...:rolleyes:

It is an intriguing issue Bob but not one I'm going to lose any sleep over. The technical side of it is way over my head but just for kicks and giggles I tried a comparison a little earlier and my ears can't detect the difference. I'm sure there are a million reasons as to why not but I couldn't care less as long as that remains the case ;)

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Originally Posted by synsei

It is an intriguing issue Bob but not one I'm going to lose any sleep over. The technical side of it is way over my head but just for kicks and giggles I tried a comparison a little earlier and my ears can't detect the difference. I'm sure there are a million reasons as to why not but I couldn't care less as long as that remains the case ;)

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Totally agree on that summation, and thankfully the other lads here are a lot more technically skilled than I to chase this paricular ghost from a more scientific and objective viewpoint.;) I am just observing...
Considering the phenomenon, it is surprising that so few are here backing up the assertion to find the cause....:mental:

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Originally Posted by bobbasrah

Totally agree on that summation, and thankfully the other lads here are a lot more technically skilled than I to chase this paricular ghost from a more scientific and objective viewpoint.;) I am just observing...
Considering the phenomenon, it is surprising that so few are here backing up the assertion to find the cause....:mental:

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Interesting discussion. I've been getting more and more interested in digital music reproduction during the past 12 months or so, which led me to 'discover' that there may be more to it than meets the eye. But it sure does meet the ear.

My inherent flaw is that I am absolutely not equipped well enough with requisite knowledge when trying to explain the differences detected by the ear. Whilst the stuff that meets the eye seems orderly and neat and everything just snaps into focus and obeys the laws of coherent logical reasoning, where things get hairy is at the ear-to-brain level. Of course, what's exacerbating the situation is that those hairy ear-to-brain experiences can oh-so-easily be explained away by generalizations such as 'expectation bias' and 'placebo'.

So we have a very peculiar situation right now where the theory is impotent when it comes to detecting any possibility of differences between extremely wild variety of digital configurations, while the practice is fertile with experiential evidence indicating audible differences. A veritable lose/lose situation when it comes to discussing these things in a civilized forum.

Let me just say this: there is, to my ears, a detectable and not so subtle difference between streaming FLAC straight into SBT vs. decoding FLAC to PCM on the Squeezebox Media Server, and then streaming PCM to the SBT player. Go figure...

As the idiom goes, "seeing is believing and hearing is a bitch."

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Originally Posted by magiccarpetride

Let me just say this: there is, to my ears, a detectable and not so subtle difference between streaming FLAC straight into SBT vs. decoding FLAC to PCM on the Squeezebox Media Server, and then streaming PCM to the SBT player. Go figure...

As the idiom goes, "seeing is believing and hearing is a bitch."

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Are we to assume that the streamed PCM to the SBT sounds better? Maybe they just sound different. Do you have any recommendations for recordings (CDs) so that we can test this out ourselves? Or can someone provide one or two high quality tracks for such a test?

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Originally Posted by dave2010

Are we to assume that the streamed PCM to the SBT sounds better? Maybe they just sound different. Do you have any recommendations for recordings (CDs) so that we can test this out ourselves? Or can someone provide one or two high quality tracks for such a test?

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Better is largely a subjective assessment. If by 'better' we are to assume smaller but more sharply focused soundstage, then yes.

Any FLAC would do, my preference is to listen to something I'm extremely familiar with (for example, Santana "Abraxas").

Thank you Alex....Finally another difference noted....

Not conversant with SBT, but when trying to find out about it, came across a similar note on a review on the Logitech site from last December which contained the following-
"Having said that I noticed that due to incoming jitter from for my nas I could hear a difference in sound quality( same song) between FLAC ( 24b 96KhZ and PCM (24b 96KHz) . With PCM is was better then with Flac. The processing power in the Touch is likely not big enough to do this job right. I converted all my HD Flac music to HD PCM to overcome this problem."
Alex's situation seems similar.

Andre mentioned a difference earlier on a HRT Streamer which is I believe a usb powered DAC (?) but has not clarified it yet.

About a year ago I experimented with streaming LPCM rather than FLAC to the SB Touch, having read that this change can improve the sound. You do this by decoding the FLACS on the server rather than let the SB Touch do it.

I got my hopes up, I was somewhat disappointed to find that I could find no difference at all. I switched back and forth several times to try to find an aspect that had changed, but failed utterly.

I reverted back again, and have left it like that since. I have a stonking Gigabit network at home, so I wonder if that was a factor in minimising any potential changes?.

I have quite a few 24/96 Vinyl rips in native WAV that I will so some experiemtation over the weekend.

Cheers,
Alex

One concern I have relates to the symmetry of the encode/decode process with FLAC. There are slightly similar issues with lossy compression, such as MP3 and AAC, but the specifications of those compression/decompression systems are such that errors are allowed, though should be within reasonable limits. There different playback/systems could, in theory, give very slightly different results. Since such systems are designed to be lossy, this should be acceptable, given the applications. Thus if different playback systems are used there could be slight differences on the same source material, within tolerance limits.

For lossless systems the specifications must be such that there is no difference between different playback systems, and the original data should be replicated precisely by the decompressed data following a round trip.

I note that systems such as FLAC contain essentially at least a lossy encoder in the encoder, and a matching lossy decoder within the lossless decoder. Some lossless systems could even have lossy encoders and decoders in the encoder, and also in the decoder. It occurs to me that if these lossy components are not matched, that this will be a possible source of errors. Indeed, the arithmetic used in such internal components could also have an effect. I don't know how well FLAC encoder/decoders have been designed, but if, for example the lossy components use floating point operations, some consideration would have to have been given to accuracy issues. However, the lossy components may have been designed using integer arithmetic, which would presumably ensure consistency across different hardware systems. The point is that for a lossless system there can be no errors, not even small ones. Small errors could arise if internal lossy components are used without sufficient care, and could thus appear at the outputs.

I just don't know enough about how systems like FLAC and Alac have been designed at the implementation level to know how robust these "standards" are. Hopefully they are robust, but I'm not sure how confident we can be of that.

Curiouser and curioser... But so far this appears limited to SBT use, not standalone DAC's hanging off a computer.

Alex, Canada - Were the sources you found the difference with normal CD rips or 24/96. and was this to the Touch to amp or through the Touch to DAC to amp?

Alex, UK - I presume that your previous test was on redbook, but this time you will be trying WAV v FLAC on hirez files? Again is this direct from the Touch or otherwise please?

Assuming as Dave has already raised, that under normal circumstance there should be no change to the decompression process, is that affected by processing power, which demands increased with the higher resolution files perhaps?