So, what's the actual state of the software?

[comradekingu]

While it is a trade off, IMO Pandora mode will draw more interest in the Pyra (e.g. because of awkward experiences with loud audio) than the boring standard mode. And I don't think either mode will actually turn (a significant number of) people away.

Considering the sensitivity of headphones vary, if it is done in TWL6040 mode, a soft limit (max level) can be set so that the loudness never exceeds damaging levels by the user.

Going the route of resampling the level down to attenuate the signal would make it very nice to have 24bit depth to work with on the DAC.

Also I think it would be less prone to scratchy potentiometer troubles, not being directly in the audio-path, which from a returns point of view could save a lot of trouble and cost.

Question, will the potentiometer, or tacho, spin all the way round? Im thinking if you set the level in software you would end up at the wrong place vis-a-vis the hardware, so that if you try to bottom it out on the wheel, it could still be playing audio.

 

[rSl]

good to hear that the twl vs. pandora audio circuit
shootout is still planned.

when i did some research on the audioquest dragonfly dac
(which i bought some time ago and sounds really awesome
to me with the beyerdynamic dt990 pro headphones) i read
that lowering volume in the digital domain reduces the
bitdepth somehow, so it would degrade audio quality.

(maybe a myth, i allready got healed from
the hires-audio crazyness by binky telling me the
shannon-nyquist theorem. thanks again binky!)


the developer of that dac was proud of the
solution to have an analog volume control that one can
change digitally via the os's volume slider,
which makes sense to me for a desktop computer, so you
don't have to reach to the dac each time you want to
change volume.
for a handheld i would prefer a thumbwheel to control
the volume, it's allready 'on hand' and one can reach
it easily.

also i plan to use pure alsa and no pulseaudio on my
future pyra, so please keep it k.i.s.s. and alsa-only
friendly.

so i think i'm still for the pandora circuit with the simple
analog volume wheel being truely analog.

 

[TrashyMG]

It will have pulseaudio, feel free to uninstall it.

 

[Grench]

So, I had another silly idea...  one wheel, multiple functions.Lid open & wheel is nothing.Pyra (super) & wheel is headphone volume.Lid closed (super) & wheel is headphone volume.Shift (either) & wheel is speaker volume.Etc...Ok, silly, but maybe a valid function theory?

Heh, if it was exposed as an input device that generated volume up/down keypresses you could do this in FunKeyMonkey .

Not really practical in any case because of volume depending on the absolute position of the wheel. Consider having headphones at 0% and speakers at 50%, with the volume wheel at 50%. Now try to set headphones to 10%. You'd need to go down from 50%, which is probably quite loud, even though you're technically moving up from 0%.

I already thought of that.  In the 'digital wheel' model using the TWL6040 audio, the change from one 'level' to another should create a signal.  In the above model having no button pressed and the lid open does nothing.  This allows the user to pre-position the wheel to approximately where they want it, then press the shift/Fn/Alt/Ctrl or combination of those and turn the wheel 1 unit in any direction to have that particular audio output or system input or other jump to that level.  So, you could pre-position it to approximately 50%, hold Super/Pyra and then turn the wheel slightly to have the headphones jump to that level and be 'run' up/down from there.

So - it would be possible and semi-practical, but still completely silly and irrelevant for the current stage of development.

The important part is to understand that the wheel can be interpreted digitally by the TWL6040 OR analog by the Pandora-type on it's pre-amplifier side, but not both.  There are technical whiz bang features that could theoretically be implemented in the far future by having it digital on the TWL6040.  There is an audiophile draw to having a true analog wheel on the pre-amplifier circuit on a setup with big dedicated capacitors on it's own special amplifier.  Understanding the trade offs.  

The bigger unanswerable question right now, though, is, under each option, "How does it sound?"

 

[WizardStan]

I have the following situation on my computer with volume only control: my volume is only at 3% with these headphones.  I don't have a great deal of accuracy when I do need to adjust the volume for any reason.  If my headphones had a hardware wheel on them I could crank that way down and then software adjust from 0 to 100% as needed, and that would be fine.

You can control this for the speakers, drive them in such a way that the volume is good at 100%, but you can't control headphones, different headphones will have different impedance which means different volumes at the same output level.  And not just the impedance, but different headphone styles will behave differently.

Well, that wouldn't be an issue, as you could choose a maximum and minimum audio volume and the volume wheel would then let you change the volume inbetween. So you can decide the accuracy.

This is the #1 reason I want actual hardware volume control, so that I can use any headphones I can get and still get decent volume adjustment.

That doesn't have anything to do with hardware control. You can do the same (even more accurate) with software, but smartphones, MP3 players, etc. have annoying steps that make them that inaccurate.

That's also the reason I wanted to keep an analog volume wheel which is then converted to the actual volume and NOT one of these annoying digital wheels which sent out signals when you turn them around... and around... and around...

I think you are misunderstanding.  My headphones, on my desktop without hardware volume, have a software volume range of 0 to 3%.  If I set it to 4% that's too loud for me, and 5% will kill me.  I can crank it to 100% and you can hear them from the other side of the office.  I have never seen a volume slider let you choose decimal volumes, so I'm not entirely certain how you expect such a thing to work.  If I set the minimum volume at 0 and the max at 5 it's still going to be discrete steps from 5 to 4 to 3.

This is why I like hardware volume.  On my Pandora using the same headphones I have the software volume set to 5% and then I just adjust the hardware volume wheel depending on the situation, and it's a smooth transition from loud to quiet.

 

[levi]

when i did some research on the audioquest dragonfly dac
(which i bought some time ago and sounds really awesome
to me with the beyerdynamic dt990 pro headphones) i read
that lowering volume in the digital domain reduces the
bitdepth somehow, so it would degrade audio quality.
 

As far as I understand it, it will reduce the bitdepth.  Whether that has any impact on human perception depends on the bit depth you start with - if you're starting at 24 bit, you could lose 8 of those bits (i.e. play at 1/256th of the max loudness) and not end up with any less than 16 bit, which in blind tests, tends to be enough to replicate anything you'd want to listen to.

Even in the analogue domain, turning down the volume limits the bandwidth obtainable by your ears, I think.  We might even be better off with an all-digital (apart from the volume pot) control of volume.

 

[EvilDragon]

I think you are misunderstanding.  My headphones, on my desktop without hardware volume, have a software volume range of 0 to 3%.  If I set it to 4% that's too loud for me, and 5% will kill me.  I can crank it to 100% and you can hear them from the other side of the office.  I have never seen a volume slider let you choose decimal volumes, so I'm not entirely certain how you expect such a thing to work.  If I set the minimum volume at 0 and the max at 5 it's still going to be discrete steps from 5 to 4 to 3.

This is why I like hardware volume.  On my Pandora using the same headphones I have the software volume set to 5% and then I just adjust the hardware volume wheel depending on the situation, and it's a smooth transition from loud to quiet.

Have you connected the headset to your Linux or Windows PC and try to change the volume with the sliders?

(On Linux, you can even scale the window and make the setting more accurate)

Or which devices did you use for the test?

 

[Grench]

You may find this amusing, but I don't think I've ever plugged my headphones directly into the headphone jack on my Linux workstation.  My setup there is a bit...odd.

HP workstation with a line out going to an old analog Yamaha mixer/pre-amp.  If I use headphones at all, they get plugged into that.

From there the L&R audio go through Y cables to both channels (A/B) of a pair (Left/Right) of 32 band EQs that get the task of acting as cross-overs for the high (A) and low (B) channels that then go through two 300W/channel analog amps to Klipsch Heresy industrial slant monitors (A/high) and Pyle 15" subs (B/low) on each side.

How does that become relevant?  Because I use my Pandora to drive that when I take the system mobile once or twice a year.  See picture from the stylus thread.  Note that it is all running out of the headphone jack.



Having reliable fine control of where that volume wheel is makes a difference in this type of application - particularly when it's sitting on the front end of a 1200W continuous 2400W peak PA.  Being able to reliably attenuate that input so it doesn't run too hot makes a big difference.

 

[the_marshal]

It makes sense that lowering the volume would lower the bitdepth. So maybe something to considering... however it's unclear to me how much real impact this could have.  For the final audio reproduction, even 16bit (96db SNR without dithering) is considered good enough. Even more so if you consider the ambient noise of most listening environment. Also most music/audio will use much less dynamic than this.

Also I think that if you're listening at a lower volume, the dynamic you can reproduce will be limited by your environment. A quite bedroom at night is ~30db, a quit library ~40db. If you're listening with a peak volume of 90db, this should give you a maximum of 50-60db usable dynamic range.

Back to the volume wheel. I like the fact you're still considering an analog potentiometer even for software audio control.

Personally I would not mind having a real analog wheel for the headphone output and the rest be software. That's where I see the real value. The built-in speaking usually don't go loud enough to be a real concern. When using HDMI or audio out, you can usually set the volume on the receiving end.

Regarding the kernel / software devolvement, it's quite a interesting discussing. I am certainly not the most qualified to comment.

I think establishing a list of priority make sense, it might help with people contributing. Also, it should give the community an idea of everything left to do / could be improved.

Seems like a lot of hard work, especially at the kernel/driver/basic OS level. I think having qualified paid developer make sense.

I can understand that before the Pyra actually makes money, this could be a challenge. I would actually not mind a push for donation to the software development.

I think for this to really work, a list of task and doing some reporting of advancement / what has been achieved would definitely help.

 

[elvissteinjr]

Volume wheel aside (I'm fine as long as it works), I'm willing to write up some of the missing UIs using C++ and wxWidgets if no one else wants to. I'm neither a kernel hacker nor much of an linux expert, but as long as I just have to write to config files or run scripts to get the actual work done, I could do that.
That would also require wxWidgets to be pre-installed in the default distribution. While it's not quite the small library, it's also used in some popular applications, so it could be well worth having it anyways (I'm not experienced native GTK or Qt, sorry).

I don't have much time currently (I will in a few weeks though), so I didn't offer my help on the IRC yet, but since this came up right now I might as well ask if the software dev team would be even fine with handling it like that.

 

[TrashyMG]

I Just see a slew of software nightmares involved with the TWL6040, you make it too feature heavy and unexpected things happen. Perhaps limit volume control to the current output device without any modifier complexities. Overall using a potentiometer and an ADC puts in an odd quirk to the mix vs if it had a rotary encoder or push buttons as a potentiometer has a dynamic value that could change if between different volume controls (HDMI vs Headset..etc) and not based on a stored value. The latter requires a bit of trickery to make work properly.

To me as prior posts suggest I suggest the Pandora Method, it's simpler, true analog volume control was a praised feature on the Pandora, however I'm willing to wait and see what the audio quality tests return.

EDIT: clarification... 

 

[EvilDragon]

Yes, but using Pandora audio is not that easy, sadly. The OMAP5 has some stuff removed AFAIK which the OMAP3 used for that.

 

[WizardStan]

Have you connected the headset to your Linux or Windows PC and try to change the volume with the sliders?

(On Linux, you can even scale the window and make the setting more accurate)

Or which devices did you use for the test?

Yes, on Windows at work, on my Arch desktop, on the Pandora.

At work my range is 0, 1, 2, or 3, with 4 being too loud for my taste generally.

My home desktop running Arch is a little better, I can go to 7, but that still only leaves me 8 discrete steps, the difference between 6 and 8 is very noticeable.

I actually keep my Pandora at 25% but since it has the hardware volume wheel I can easily turn it up or down.

Software volume control just isn't precise enough, it's only useful if 100% is a viable loudness, the difference between 80% and 81% is negligible.  If max volume is only 10% then you've got 1/10th as many steps, going from 8 to 9 is a big jump.

 

[EvilDragon]

Have you enabled attenuation for the volume slider? That setting makes everything usually -6dB to -12dB more silent, which increases the slider range for headphones a lot (0 to 4 will then become 0 - 50, so you got more than 10 times more steps inbetween).

 

[WizardStan]

I have no idea where that option is.

 

[EvilDragon]

I have to check, but I know I found it somewhere hidden away...

 

[BaDToaD]

The bigger unanswerable question right now, though, is, under each option, "How does it sound?"

This is one of the most important questions ever asked about the Pyra. How does it sound is totally different to how does it perform on paper too

 

[hns]

The bigger unanswerable question right now, though, is, under each option, "How does it sound?"

This is one of the most important questions ever asked about the Pyra. How does it sound is totally different to how does it perform on paper too

We simply do not know an answer yet. Nobody knows.

Well, we know that a single speaker connected to the twl6040 on a PandaBoard sounds loud and not too bad. But that's it. There are so many influencing factors that you are right that it must be determined experimentatlly.

This is why we urgently want to build the final prototypes and want to modify one of them to have the other hardware option. And after optimizing the software we can do audible comparisons (and signal measurements). But not earlier  

 

[comradekingu]

I would love to try a softvolume one. If all goes to pot you can use the wheel for an external DAC/AMP.

That is a bonus to consider. It services another whole segment of the portable hifi/pro audio crowd.

 

[WizardStan]

I have to check, but I know I found it somewhere hidden away...

Well regardless, the point is that it's a feature to be able to set two volumes, a software for the maximum and the hardware for full spectrum, and reducing it to just software volume subtracts this feature, a feature which I rely on.