Gapless playback?

@takla wrote:

 

I repeated the point about perception of sound quality for a couple of reasons:

 

1: terms like ‘thin and scratchy’ are entirely subjective and impossible to quantify and may mean different things to different people.  If different people have a different idea about what it means then maybe they will think they are dealing with the same issue when actually they each have in mind something else.  If a problem can’t be reliably identified and quantified how to tell if it is fixed?

 

2: The only sure way to demonstrate that there is a problem of this nature is to abx/blind test it, because the placebo effect is surprisingly powerful and none of us is immune. Some people feel very doubtful about this, some people get upset and feel that they simply cannot be affected and that to suggest otherwise is a personal insult. However placebo effect is well known, factual and measurable and used in all kinds of tests and trials from pharmaceuticals down to humble audio device and codec reviews.  I have to say I felt slightly wounded on discovering that most of the time I can’t hear the difference between a LAME V4 MP3 and flac, but there it is, a simple test shows my ears are not as golden as my ego, and that ears and mind in combination do not make for an objective tool.

Thank you, Takla.  A few links for those individuals who still think they are immune from the placebo effect:

http://home.provide.net/~djcarlst/abx_plac.htm,

http://bruce.coppola.name/audio/Amp_Sound.pdf,

http://www.nousaine.com/pdfs/Wired%20Wisdom.pdf,

 

More information on ABXing:

http://en.wikipedia.org/wiki/ABX_test,

http://wiki.hydrogenaudio.org/index.php?title=ABX.

 

ABX is a type of double-blind test.

http://gizmodo.com/315250/pear-cable-chickens-out-of-1000000-challenge-we-search-for-answers.

 

Why anti-ABX?

http://en.wikipedia.org/wiki/Confirmation_bias,

http://en.wikipedia.org/wiki/Post-purchase_rationalization.

@flactastic wrote:

No, I’m not even going to attempt to explain to you what “thin and scratchy” means - whatever I say you will just argue with it. I have already said I will be performing an RMAA test, so save your opinions for when I post that. I am going to measure the distortions, and am going to use a good cable (or a “silly cable” as someone said) so that nothing else can influence the results. The answer to your last question is: yes.

 

 This test takes like 20 minutes.  Instead of arguing about nothing, you could just run the test and settle this already.

I apologise to all who I have offended.  Maybe I over-reacted.  Didn’t like being told not to bother with "“silly cables” and a couple of other comments riled me. My bad, I shouldn’t have reacted.

Yeah, the test is quick enough, I was just waiting for the adaptors so I can connect my silly cables. :wink: The only cable I had to hand was rubbish, so I have only really been able to verify speed differences, not distortions (the cable adds so much distortion and hum itself).

Oh - if anyone could kindly point me to where you change the pitch on the player (in Rockbox), I would be humbly grateful.

UPDATE

Anyway, I have all my cables in order now, and performed the test - or at least I tried to.  Unfortunately this was what I got:

“Cannot finish tests. \nAUDIO ERROR: Cannot detect test signal in the recorded waveform. Probably the input level is too low.  Try to check I/O levels.  No hardware error occured.”

When I did the pre-test, it was telling me the signal was about 18dB too low and suggested to try to increase the levels on the mixer. Unfortunately, I’m running everything at absolute max level (on my soundcard’s GUI and on the Sansa). It’s just that even at max level, the Sansa is very quiet (a bit louder using Rockbox but still very quiet).

I hasten to add, I have disabled any European-regulated volume limitations - and it is still very loud through headphones, but is simply not up to line level.

Good news is, I have a dock on order, which will enable me to get a line level from the player (not via the headphone output). This should enable me to complete the test.

Other good news is, I agree with those who mentioned about the possibility of placebo - I am starting to think this may be the case - none of us is immune to that. It will be good to run the test anyway, but I will not hesitate to admit if it has all been “in my head”!!! :stuck_out_tongue:

However, please let us wait for the test results.  I should have my dock in a few days - or someone else could run the test if they want.

Message Edited by FLACtastic on 05-30-2010 06:47 PM

Message Edited by FLACtastic on 05-30-2010 08:23 PM

@flactastic wrote:

 

Yeah, the test is quick enough, I was just waiting for the adaptors so I can connect my silly cables. :wink: The only cable I had to hand was rubbish, so I have only really been able to verify speed differences, not distortions (the cable adds so much distortion and hum itself).

 

 Cables don’t add hum and distortion.  If you have hum and distortion, its due to something else and you should look into that.

FLACtastic wrote: 

 

 

 

Anyway, I have all my cables in order now, and performed the test - or at least I tried to.  Unfortunately this was what I got:

 

“Cannot finish tests. \nAUDIO ERROR: Cannot detect test signal in the recorded waveform. Probably the input level is too low.  Try to check I/O levels.  No hardware error occured.”

 

 

Double check your PC recording settings.  You have set something wrong.  Even my laptop’s crappy onboard is more then sensitive enough for this test.  

FLACtastic wrote: 

 

Good news is, I have a dock on order, which will enable me to get a line level from the player (not via the headphone output). This should enable me to complete the test.

 

 

Thats not going to work.  Line level is roughly the same level as the headphone out, and even if it was louder I don’t think we have line out enabled in Rockbox yet.  Instead, figure out why your sound card isn’t working properly or else use a different PC.

Saratoga - first you mentioned about my “silly cables” and now you make false statements like “cables don’t add hum and distortion.”  YES they do.  Bad, old, broken cables do.

Stop making assumptions and barking orders (e.g. “You have set something wrong.” “Figure out why your soundcard isn’t working properly.” )

It’s very arrogant, and it’s rude.

Message Edited by FLACtastic on 06-01-2010 10:07 PM

@flactastic wrote:

Saratoga - first you mentioned about my “silly cables” and now you make false statements like “cables don’t add hum and distortion.”  YES they do.  Bad, old, broken cables do.

 

Stop making assumptions and barking orders (e.g. “You have set something wrong.” “Figure out why your soundcard isn’t working properly.” )

 

It’s very arrogant, and it’s rude.

 

 

FWIW,  if my Sansa is turned all the way up it is somewhat louder into my stereo than other line level devices like the tuner and CD player.  It seems very odd that it would be roughly 20 dB too low for a sound card looking for “line level” input.That’s a factor of 10 in voltage.

 

Message Edited by donp on 06-01-2010 10:04 PM

@flactastic wrote:

Saratoga - first you mentioned about my “silly cables” and now you make false statements like “cables don’t add hum and distortion.”  YES they do.  Bad, old, broken cables do.

 

 

A broken cable does not produce hum.  You are simply mistaken.  

And anyway, you didn’t say the cable was physically broken.  You said it was cheap, and that you were able to test with it.  Either what you said about testing with it was wrong, or what you’re saying now is mistaken.  Please don’t expect me to read your mind.    

FLACtastic wrote: 

 

Stop making assumptions and barking orders (e.g. “You have set something wrong.” “Figure out why your soundcard isn’t working properly.” )

 

It’s very arrogant, and it’s rude.

 

 

 

  

I didn’t give you an order, I simply told you what you need to do to make this work, and explained why what you were doing was not going to work.  You’re perfectly welcome to continue to be unable to do what you set out to do and I will not mind.  But do not insult me for trying to help you succeed.  I have good intentions even if you choose not to be helped.  

And FWIW assuming you’ve got a problem when your line out level is 20 dB below line out level isn’t much of an assumption :slight_smile:  I hardly think I’m being arrogant in thinking something is very, very wrong here.  

From the sidelines, this is really a clash of cultures.

Saratoga (and Takla too, I’d guess) are programmers. They are used to dealing with computers as logical devices that accept comands and execute them. The commands work, or they don’t work.  If they don’t work, they try a different set of commands. Programmers think, and offer advice, in step-by-step imperatives. 

Yes or no. 1 or 0. Logic.  “Either what you said about testing with it was wrong, or what you’re saying now is mistaken.”

They’re not trying to boss you around, FLACtastic. They’re applying calm logic and offering you programs–sets of commands to accomplish the purpose. They have thought about the problem and are trying to give you the steps that will solve it in the most direct form. 

It’s not about who’s in charge. It’s about solving the problem. 

Second that: cables cannot add hum or distortion.

Maybe if they were wrapped around a transformer. :wink:

Cables can indeed add hum and distortion, it’s all about the signal-to-noise ratio.  As your source signal drops, the noise becomes more pronounced.  As for hum, if you have a high cable resistance, such as a bad shield connection in particular, you will pick up all kinds of interference on the signal lead.

The longer the cable run, the stronger the likelihood of noise.

For a basic test with a sound card “aux” input, you should be able to use a basic portable device patch cord.  The application you are using is “one-dimensional”, simply looking at the overall signal.  More subjective testing, with your ears, may hear subtle nuances.

The epic battle between raw engineering and listening tests reminds me of Bob Carver and his “transfer function” marketing blitz years ago.  Now that was fun.

Bob  :smileyvery-happy:

@neutron_bob wrote:

Cables can indeed add hum and distortion, it’s all about the signal-to-noise ratio.  As your source signal drops, the noise becomes more pronounced.  

 

 Noise from the source and receiver.

neutron_bob wrote: 
As for hum, if you have a high cable resistance,

 

 

  

Which cables made of metal do not.

neutron_bob wrote: 
 such as a bad shield connection in particular, 

 

Which is not physically possible since a bad shield connection does not increase resistance.

  

neutron_bob wrote: 

 you will pick up all kinds of interference on the signal lead.

 

 

So if you use cables that don’t exist in a situation thats not possible, something that doesn’t make sense happens.  Got it. This was a valuable contribution to the thread.  

  

neutron_bob wrote: 

 More subjective testing, with your ears, may hear subtle nuances.

 

 

lol

@neutron_bob wrote:

 

More subjective testing, with your ears, may hear subtle nuances.

Subjective testing is often unreliable.  This is why objective testing is often preferable.  Please see message 363 of this thread and http://www.theaudiocritic.com/downloads/article_1.pdf for the explanation.

neutron_bob wrote: More subjective testing, with your ears, may hear subtle nuances.

 

 

Only if you have the right accessories, some of which are available at very reasonable prices from  http://www.machinadynamica.com/

If you’re using the wrong kind of pebbles or you don’t have the  Frog Jump in Water Sound
Room Acoustics Tweak
then how do you know you are hearing the correct and genuine subtle nuances???

Message Edited by Takla on 06-03-2010 01:00 AM

I want to clarify the shielded comment since I was a little unfair.  I suppose some shielded cables do use a common ground as a shield line, if so breaking one of them does increase the resistance (a lot!).  However, the result is not hum, in that case you have no common line!   You’ll get a weird mixing of the left and right channels as they try to force current into one another.  Rather then hum you’ll get mixing of the channels and near total loss of signal since you no longer have a real electrical circuit.  

Hehe, I work with test equipment daily.  Glitches are a common occurrence, depending upon the cables used.  Working with the oscilloscope, where the probes are grounded can make all the difference, especially since we have a digital processor and multiplexed display active.  Quite often, I choose to limit the bandwidth in order to see a clean sample.  I don’t know how sensitive the test software might be in your case.

With the typical portable cable (stereo mini plug), I see damaged conductors at the plugs and strain relief points.  If cables are abused and kinked, the shielding can be pinched making a wee capacitor in the line.  Small signal cables can have the two Sig+ wires twisted or as a parallel pair.

As far as the sonic differences are concerned, this is only an issue at the extremes, of course.  With a little Sansa, we have quite short cables.  With the average studio runs, you can have microphones twenty meters or more from the console, a much more pronounced issue- those cables are expensive.

Bob :stuck_out_tongue:

@neutron_bob wrote:

Hehe, I work with test equipment daily.  Glitches are a common occurrence, depending upon the cables used.  Working with the oscilloscope, where the probes are grounded can make all the difference, especially since we have a digital processor and multiplexed display active.  Quite often, I choose to limit the bandwidth in order to see a clean sample.  I don’t know how sensitive the test software might be in your case.

 

With the typical portable cable (stereo mini plug), I see damaged conductors at the plugs and strain relief points.  If cables are abused and kinked, the shielding can be pinched making a wee capacitor in the line.  Small signal cables can have the two Sig+ wires twisted or as a parallel pair.

 

 

 

 

Great, but no one said you can’t break a cable.  I don’t doubt if you rip the wires out it doesn’t work as well.  What you said was:

"Cables can indeed add hum and distortion "  

Do you want to take that part back?  Because it seems like you’ve changed your mind.   

Message Edited by saratoga on 06-03-2010 02:10 PM

this thread is TLDR

just checkin in to see if this thing is gapless yet and if it’s even on the horizon?

(rockbox is too technical for the wife so i want to use the sansa firmware)

@emagon4523 wrote:

this thread is TLDR

 

just checkin in to see if this thing is gapless yet and if it’s even on the horizon?

 

(rockbox is too technical for the wife so i want to use the sansa firmware)

 If she isn’t worried about gapless, set it up so the default is Sansa firmware, and you boot to rockbox when you’re using it.  There’s info on how to do that on the rockbox site.

 

Can I just add another plea for gapless playback (at least when playing lossless files like FLAC)? Or maybe enable cue support so we can rip CDs to a single file and get gapless by that method?

I’m loving gapless functionality via Rockbox. However, as I’m sure you know, Rockbox doesn’t currently support line-out functionality (it only plays through the headphone-out) so this means if I want to play my Fuse V2 through my stereo (via my dock) or use a portable headphone amp (via the line-out) I have to use the Sansa firmware - and lose the gapless ability. :frowning:

So, come on good firmware developers, PLEASE continue working to give us gapless!  If Rockbox can do it, I know YOU can too! :wink: