INTERACT FORUM

Please login or register.

Login with username, password and session length
Advanced search  
Pages: [1]   Go Down

Author Topic: What exactly - does the "blue" light (EQ icon) stand for with JRiver?  (Read 7050 times)

Vocalpoint

  • Citizen of the Universe
  • *****
  • Posts: 2007

Folks,

I had always believed this "blue" indicator (see attachment) meant the user was getting a "bit perfect" audio path from MC to hardware.

But we have a bit of chatter in this thread:

http://yabb.jriver.com/interact/index.php?topic=100452.new;topicseen#new

To the contrary.

Can anyone confirm what it does mean (if anything)?

VP
Logged

Hendrik

  • Administrator
  • Citizen of the Universe
  • *****
  • Posts: 10768
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #1 on: April 27, 2016, 03:09:26 am »

The EQ icon will turn blue when no processing is being performed other than volume, and the output bitdepth is sufficiently high for the input to be properly represented.
We don't consider volume a destructive operation in this case since its more of a necessity to not blow your speakers or your ears out. If you want to be sure volume is also not affecting things, you should set volume mode to "disabled" (or check the audio path), but you will likely perform volume correction at one point or another in the processing chain, so arguing about bitperfectness with volume seems a bit redundant.
Logged
~ nevcairiel
~ Author of LAV Filters

dtc

  • MC Beta Team
  • Citizen of the Universe
  • *****
  • Posts: 3025
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #2 on: April 27, 2016, 01:07:34 pm »

Hendrik - In general you are correct that changing the volume is not a destructive process, but there are some instances where it it. For HDCD recordings sent to a DAC that understands HDCD, changing the volume will destroy the HDCD coding and the HDCD light will not light up. Also, for DoP signals, changing the volume will completely change the DoP encoding, as RD James keeps pointing out. There may be other examples, but those are two examples where changing the volume is a destructive process. Maybe the Audio Path should be blue for bit perfect and green (or some other color) when only the volume is being changed.

Also, I, and probably some other old folks, primarily change the volume with the volume control on my analog preamp. So, no, I do not perform digital volume correction at some point in the chain. I actually have volume disabled in MC, just so no changes get made to the volume in the digital domain.

In the Wiki, there is no mention of volume. It says that any and all changes to the signal are reported. Maybe the Wiki should be updated to include this information about how volume is treated.

Sorry to be picky, just thought I would point out some admittedly rare exceptions, but exceptions never the less.
Logged

blgentry

  • Regular Member
  • Citizen of the Universe
  • *****
  • Posts: 8009
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #3 on: April 27, 2016, 01:21:23 pm »

I don't think that you can argue that changing volume is "not a change to the digital data".  MC's volume changes, absolutely positively change the digital data.  Using words like "destructive" or "harmful" are meaningless in this context because a change is a change.

Hendrick's argument that the volume may be changed by other gear outside of MC, in the digital domain, is ancillary.  That may, or may not happen.  But we can be sure when MC is changing the volume and thus changing the digital samples.

Now why would anyone care?  Perhaps if you use a multi-bit DAC and you want to be really really sure you deliver the as-recorded samples to your DAC.  Or maybe keeping all samples intact just makes you feel better about the digital playback process.  Or maybe you think you hear a difference between manipulated samples and original samples.  Whatever the reason, when MC makes volume changes, it changes the samples.

So as I said, the blue light is not a "bit perfect" or "no changes" light.  It's something else.  I'm not upset about it or anything, because I know how to read the playback path window.  I just think it's important to be accurate about what something is or is not.

Brian.
Logged

Vocalpoint

  • Citizen of the Universe
  • *****
  • Posts: 2007
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #4 on: April 27, 2016, 01:29:20 pm »

So as I said, the blue light is not a "bit perfect" or "no changes" light.  It's something else.  I'm not upset about it or anything, because I know how to read the playback path window.  I just think it's important to be accurate about what something is or is not.

Wow - I am surprised by the information here but at least I know where we stand.

I will be mindful of these facts from now on when someone asks me about bit perfect playback in MC.

VP
Logged

mwillems

  • MC Beta Team
  • Citizen of the Universe
  • *****
  • Posts: 5181
  • "Linux Merit Badge" Recipient
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #5 on: April 27, 2016, 01:43:16 pm »

I don't think that you can argue that changing volume is "not a change to the digital data".  MC's volume changes, absolutely positively change the digital data.  Using words like "destructive" or "harmful" are meaningless in this context because a change is a change.

Hendrick's argument that the volume may be changed by other gear outside of MC, in the digital domain, is ancillary.  That may, or may not happen.  But we can be sure when MC is changing the volume and thus changing the digital samples.

Now why would anyone care?  Perhaps if you use a multi-bit DAC and you want to be really really sure you deliver the as-recorded samples to your DAC.  Or maybe keeping all samples intact just makes you feel better about the digital playback process.  Or maybe you think you hear a difference between manipulated samples and original samples.  Whatever the reason, when MC makes volume changes, it changes the samples.

So as I said, the blue light is not a "bit perfect" or "no changes" light.  It's something else.  I'm not upset about it or anything, because I know how to read the playback path window.  I just think it's important to be accurate about what something is or is not.

Brian.

Brian, I think you're missing a key part of what Hendrik said:

The EQ icon will turn blue when no processing is being performed other than volume, and the output bitdepth is sufficiently high for the input to be properly represented.

MC automatically sends output to the DAC at the highest bitdepth the DAC supports (typically 24 bit these days, but sometimes 32 bit).  Most source material is 16-bit.  Passing 16-bit audio data as 24-bit data is lossless because the extra eight bits are just padded with zeroes.  You can argue whether that's "bitperfect," but most people agree that it is because all of the original audio data is present and recoverable in its original form.

If you digitally change the volume on such a signal it's no different than zero padding the bottom unless you add more than 8 bits of attenuation.  If you attenuate by, say 18dB you'll have 3 bits of zeroes at the "top" and 5 bits of zeroes at the "bottom."  All the original audio data is still present and recoverable in its original form.  It's every bit as "bit perfect" as the basic bitdepth padding case.  The samples aren't changed except with respect to scale. We know this because JRiver can do thousands of volume manipulations on a signal and (as long as it doesn't run out of "pad") can output a full-scale signal that is bit identical to the original signal (this has been tested).

Now if you're dealing with special encoding, or attenuating more than the "pad" allows, then you're correct, you're losing some very quiet portions of the original audio data, but for someone listening to Red Book CD on a 24-bit DAC, JRiver is still bitperfect (in the sense of all original audio data being present and recoverable) down to -48dB of attenuation.

So I think it's a little misleading to say that "samples are being altered."  In the case of redbook audio with a typical DAC, the samples are not being altered anymore than they're being altered by lossless compression (which also "changes the digital data" in the strict sense, but only in ways that allow perfect reconstitution of the original).  They're being altered with respect to their volume, but in no other respect, and all original data is (except in the special cases mentioned) still present in the output stream.  

None of this applies to higher bitdepth material or with lots of attenuation, but based on Hendriks comment the light should turn off in those cases (I'm not in front of MC so cannot test)?  In any case, my point is that merely adjusting volume doesn't necessarily affect "bitperfectness" anymore than lossless compression or bitdepth padding do.
Logged

Matt

  • Administrator
  • Citizen of the Universe
  • *****
  • Posts: 42022
  • Shoes gone again!
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #6 on: April 27, 2016, 01:58:45 pm »

The blue light comes on any time we're not making any harmful changes.  It's not a "bit perfect" light but instead a "this is as good as it gets" light.

We think volume is the one change that it's safe to make.  We perform the volume calculations in the 64-bit space and now have configurable dithering.

There's just really no way the signal could be better at the level you're driving it when the light is on.  It could be louder, but that's a different beast.
Logged
Matt Ashland, JRiver Media Center

dtc

  • MC Beta Team
  • Citizen of the Universe
  • *****
  • Posts: 3025
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #7 on: April 27, 2016, 02:18:44 pm »

The blue light comes on any time we're not making any harmful changes.  It's not a "bit perfect" light but instead a "this is as good as it gets" light.

We think volume is the one change that it's safe to make.  We perform the volume calculations in the 64-bit space and now have configurable dithering.

There's just really no way the signal could be better at the level you're driving it when the light is on.  It could be louder, but that's a different beast.

In most cases it is safe to make a volume change. But, per my examples above, I do not think it is always safe. The DoP issue which has been discussed several times is one example where volume change has caused some people some real pain. HCDC is not that common, but some DACs still use it. Two colors or at least a comment in Audio Path about volume change would be a nice extra piece of information.
Logged

Hendrik

  • Administrator
  • Citizen of the Universe
  • *****
  • Posts: 10768
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #8 on: April 27, 2016, 02:30:16 pm »

The DoP issue which has been discussed several times is one example where volume change has caused some people some real pain.

MC will not modify the volume of DoP signals by itself, hence from all its doing it leaves MC bit-perfect. System Volume is another beast.
Logged
~ nevcairiel
~ Author of LAV Filters

dtc

  • MC Beta Team
  • Citizen of the Universe
  • *****
  • Posts: 3025
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #9 on: April 27, 2016, 02:36:51 pm »

MC will not modify the volume of DoP signals by itself, hence from all its doing it leaves MC bit-perfect. System Volume is another beast.

Agreed, but if system volume is not at 100 then the signal is still not bit perfect and, if MC knows that it would be nice to show that. This whole issue is not MC's fault, but it would be nice if it could help with the solution, even by just saying that system volume is effecting the original signal.
Logged

mojave

  • MC Beta Team
  • Citizen of the Universe
  • *****
  • Posts: 3732
  • Requires "iTunes or better" so I installed JRiver
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #10 on: April 27, 2016, 02:43:41 pm »

Agreed, but if system volume is not at 100 then the signal is still not bit perfect and, if MC knows that it would be nice to show that. This whole issue is not MC's fault, but it would be nice if it could help with the solution, even by just saying that system volume is effecting the original signal.
That is what the Audio Path does in a very detailed manner.
Logged

dtc

  • MC Beta Team
  • Citizen of the Universe
  • *****
  • Posts: 3025
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #11 on: April 27, 2016, 02:50:26 pm »

That is what the Audio Path does in a very detailed manner.

It does not show system volume changes or settings, even if you change system volume from within MC.
Logged

blgentry

  • Regular Member
  • Citizen of the Universe
  • *****
  • Posts: 8009
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #12 on: April 27, 2016, 04:45:13 pm »

Brian, I think you're missing a key part of what Hendrik said:

MC automatically sends output to the DAC at the highest bitdepth the DAC supports (typically 24 bit these days, but sometimes 32 bit).  Most source material is 16-bit.  Passing 16-bit audio data as 24-bit data is lossless because the extra eight bits are just padded with zeroes.  You can argue whether that's "bitperfect," but most people agree that it is because all of the original audio data is present and recoverable in its original form.

I agree so far.

Quote
If you digitally change the volume on such a signal it's no different than zero padding the bottom unless you add more than 8 bits of attenuation.  If you attenuate by, say 18dB you'll have 3 bits of zeroes at the "top" and 5 bits of zeroes at the "bottom."

I only agree here in multiples of 6 dB.  Subtracting 6 dB is just like you said:  Shifting the whole bit sequence own by one bit and dropping the bottom bit, which was zero to begin with in this case.  (Since we are talking about 16 bit data zero padded up to 24 bits).

But what about subtracting any value other than 6 dB?  Everything other than 6 dB (or multiples of) is going to be a calculation which is going to discard data and require dithering.  I could do some math here, but I'm sure you can see that trying to subtract 3 dB is not anywhere close to a bit shift or "bit perfect" operation.  So I stand by my original argument.  Volume adjustments alter the data.  If you don't agree, let's do some digital math and make this a concrete illustration.

Brian.

Logged

mojave

  • MC Beta Team
  • Citizen of the Universe
  • *****
  • Posts: 3732
  • Requires "iTunes or better" so I installed JRiver
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #13 on: April 27, 2016, 05:36:38 pm »

Here is the formula for calculating effective bit-depth:
Bit-depth = output bit-depth
     example:  24
dB = decibel attenuation as a negative number
     example:  -20

=LOG(POWER(10,20*LOG10(POWER(2,Bit-depth))+dB),2)/20

With this formula you lose one bit per 6 dB of attenuation when both the DSP and output bit-depth are 16 bit.

However, if the DSP processing is at a higher bit-depth than the output bit-depth and the output is dithered, you gain 4 effective bits.

=LOG(POWER(10,20*LOG10(POWER(2,Bit-depth))+dB+4),2)/20

64 bit processing with 24-bit output results in 16.04 effective bits at a volume of -72 dB.

64 bit processing with 32-bit output results in 16.07 effective bits at a volume of -120 dB.
Logged

RD James

  • Citizen of the Universe
  • *****
  • Posts: 1871
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #14 on: April 27, 2016, 05:41:30 pm »

Also, for DoP signals, changing the volume will completely change the DoP encoding, as RD James keeps pointing out.
My issue is that JRiver is not setting the system volume to 100% with DoP playback or other bitstreaming options.
JRiver itself is not touching the volume of the bitstream, it's just not preventing the system from doing so.
 
The EQ icon will turn blue when no processing is being performed other than volume, and the output bitdepth is sufficiently high for the input to be properly represented.
I don't think this calculation is working in the current build.
When volume is at 1% (-95.5dB) and I play a 16-bit file with a 24-bit (padded) output, it still lights up blue. Once it drops below -48dB it shouldn't light up any more. (or should it be -42/-36 to account for dither?)
Same thing for any amount of volume reduction with a 16-bit file and a 16-bit output.
 
Volume adjustments alter the data.
Yes, but not in a meaningful way if you use the new TPDF option in JRiver.
With their 64-bit audio path this is effectively a lossless process.
There is no distortion added, the only change is that the noise floor increases as you reduce the volume.
If you use the "bit-exact" or "no dither" options, then you have a point, as these will add distortion.
 
I wonder if a "bit-exact" mode for the volume control might be possible.
Every bit is something like 6.01dB so what about a mode which disables dither and only lets you adjust volume in 1-bit steps?
 
Frankly, I don't see the need since TPDF was added, but it might be an interesting option to have.
Logged

dtc

  • MC Beta Team
  • Citizen of the Universe
  • *****
  • Posts: 3025
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #15 on: April 27, 2016, 05:54:43 pm »

My issue is that JRiver is not setting the system volume to 100% with DoP playback or other bitstreaming options.
JRiver itself is not touching the volume of the bitstream, it's just not preventing the system from doing so.


I understand. But if they are reporting everything that is happening to the file, I think it would be nice if they also reported the system volume, especially since MC can change it. Audio Path shows other volume changes, why not system volume? MC has the information, why not report it?
Logged

JimH

  • Administrator
  • Citizen of the Universe
  • *****
  • Posts: 71589
  • Where did I put my teeth?
Re: What exactly - does the "blue" light (EQ icon) stand for with JRiver?
« Reply #16 on: April 27, 2016, 05:55:10 pm »

Please don't waste our time.  There are other forums where you can argue about audiophile minutiae.

Closing this now.
Logged
Pages: [1]   Go Up