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Downmixers....
Old 28th July 2020
  #1
Gear Addict
 
🎧 10 years
Downmixers....

Got a little burnt recently down mixing 5.1 content to stereo. I’m exploring options in the downmix realm. Not sexy, but a reality.

Had some delay issues with a 5.0 avid downmixer...
and I love justin at cargo cult. He’s a genius. But the spanner downmixer consistently makes lower loudness when I downmix. (And I love spanner. It’s awesome.)

What’s everyone’s downmixer of choice? Considering the nugen as I enjoy using halo and vis lm. I met the folks at nugen at nab this past year. Very bright folks. Any experience with halo downmix?

I don’t have as much time as I like to demo various options. I was hoping to get a jump on things with your input.
Old 28th July 2020
  #2
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pentagon's Avatar
 
🎧 10 years
How can Spanner “consistently makes lower loudness”?
It is what you set it. User responsibility —- there’s no magic to it. It’s a channel/level router/mixer with a great UI which helps with setting up automation.

Halo Downmix is an algorithmic approach. Spanner is routing made easier (as in you could set that all up with auxes but this does it as one insert.)
Old 28th July 2020 | Show parent
  #3
Gear Addict
 
🎧 10 years
Quote:
Originally Posted by pentagon ➡️
How can Spanner “consistently makes lower loudness”?
It is what you set it. User responsibility —- there’s no magic to it. It’s a channel/level router/mixer with a great UI which helps with setting up automation.

Halo Downmix is an algorithmic approach. Spanner is routing made easier (as in you could set that all up with auxes but this does it as one insert.)
I hear ya! That’s what I thought too! Try it for yourself. I took a 5.1 print master ran it through spanner. L & R at unity. Center down 3. Ls and Rs down 3. Just like you should. Resulting stereo consistently 2-3 dB lower when I compared it to the 5.1 trough VisLm. I mean, please, tell me where I messed up. I’d prefer to be wrong in this case! If I have a chance post post a screenshot tomorrow.
Old 28th July 2020 | Show parent
  #4
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pentagon's Avatar
 
🎧 10 years
What I bolded is wrong. That's the first thing I noticed.
When sending a discrete center into Spanner 5.1/2 plugin, it respects the equal panning law which means, L and R are already getting a -3dB center signal each. If you are additionally pulling down the center -3dB, then you have obviously overcompensated.

You can check it with a signal generator. This is also true for Pro Tools (well modern versions): a mono bussed to a stereo will be -3dB on each left and right. Not full signal on both left and right.

Quote:
Originally Posted by postprosound ➡️
I hear ya! That’s what I thought too! Try it for yourself. I took a 5.1 print master ran it through spanner. L & R at unity. Center down 3. Ls and Rs down 3. Just like you should. Resulting stereo consistently 2-3 dB lower when I compared it to the 5.1 trough VisLm. I mean, please, tell me where I messed up. I’d prefer to be wrong in this case! If I have a chance post post a screenshot tomorrow.
You also haven't mentioned what you are doing with the LFE. In addition, there's always the chance of phase issues on fold down which will change the summed signal levels due to channel content or mixing decisions. Most of these should not be significant enough to throw integrated loudness but depending on duration and content, it has the possiblity.

I'll leave you a link to Netflix's fold down instructions as a guide
https://partnerhelp.netflixstudios.c...tices-v1-1#1_2

I'll have to investigate how surround content is weighted for the ITU integrated loudness standards.
Old 28th July 2020 | Show parent
  #5
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Quote:
Originally Posted by pentagon ➡️
I'll have to investigate how surround content is weighted for the ITU integrated loudness standards.
Weighted +1.5LU
Old 28th July 2020 | Show parent
  #6
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🎧 10 years
Quote:
Originally Posted by postprosound ➡️
I hear ya! That’s what I thought too! Try it for yourself. I took a 5.1 print master ran it through spanner. L & R at unity. Center down 3. Ls and Rs down 3. Just like you should. Resulting stereo consistently 2-3 dB lower when I compared it to the 5.1 trough VisLm. I mean, please, tell me where I messed up. I’d prefer to be wrong in this case! If I have a chance post post a screenshot tomorrow.
Yeah you definitely should not be pulling the center channel fader on the plugin down 3dB (if that is what you are doing). It is already down three with the pan law. There are stereo presets that will give you a good start point. I use Spanner all the time and have never had any issues with lower loudness readings.

A simple test will confirm. Send -20dBFS tone on a mono track to your 5.1 mix bus and then through Spanner. Panned hard left it should read -20dBfs. Panned center it should read -23dBFS. If it reads lower then something is amiss.
Old 28th July 2020
  #7
Gear Addict
 
🎧 10 years
Thanks all for the input. Though I fully understand pan law, I completely had a duh moment and didn't think that spanner would respect pan law. I mean, of course it would! Why wouldn't it!?! I guess I got confused as the avid down mixer needs a -3 center.... They day the mind is the first to go.


Anyway, I'm still looking at the NUGEN Halo down mix. Any experiences?
Old 28th July 2020
  #8
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Andrew Mottl's Avatar
 
🎧 10 years
May I ask, what were your delay issues with Avid's Downmixer?

I use that one fairly regularly and cannot recall running into issues.
Old 29th July 2020
  #9
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Leverson's Avatar
 
🎧 5 years
Just out of curiosity I did a test exporting the same pretty complex 5 minute segment of one of my last features using the Avid Downmixer, the Nugen Halo Downmixer and Spanner. They were all each set to their 'Stereo ITU' presets.

The loudness readings for all of them ended up being exactly identical, down to the decimal point (tested using both the Pro Loudness Analyzer and the Dolby Media Meter).

Then just for fun I did a null test between the three (inverting the phase). For most of the sections the Avid Downmixer and the Halo Downmixer phase cancelled entirely. When I tested either one against Spanner the signal was almost entirely gone, but I could very very faintly hear SOME signal. The one section of my export that didn't phase cancel exactly between any of them was one section that was extremely drenched in surround reverb, but that might be due to how the reverb plugins process and generate their signals (the reverb was live running through the plugin, not pre-printed)

In any case the loudness measurements between all three were identical, using their standard ITU downmix settings. So I'd choose whichever one has the best layout or interface for you, or based on how complex you want to tweak your parameters and settings etc. But they should all do the job they need to do just fine functionally.
Old 29th July 2020
  #10
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Andrew Mottl's Avatar
 
🎧 10 years
Thanks for testing and sharing the results!!
Old 29th July 2020
  #11
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Sndnerd's Avatar
 
🎧 5 years
Thanks for this. I just fell into the trap of assuming the trim was the only thing going on with the Nugen plug. The ITU preset is actually a net -6 in the centre channel and surrounds I believe.
Old 29th July 2020 | Show parent
  #12
Deleted e479b20
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Quote:
Originally Posted by Leverson ➡️
Then just for fun I did a null test between the three (inverting the phase). For most of the sections the Avid Downmixer and the Halo Downmixer phase cancelled entirely. When I tested either one against Spanner the signal was almost entirely gone, but I could very very faintly hear SOME signal. The one section of my export that didn't phase cancel exactly between any of them was one section that was extremely drenched in surround reverb, but that might be due to how the reverb plugins process and generate their signals (the reverb was live running through the plugin, not pre-printed)
hm, down-mixing is such a simple DSP process (summing signals and sending them to an output) I think ANY plugin (and even no plugin at all) can be used to do this. Just like an MS-XY encode/decode is always the exact came process and same result essentially a sum and difference.

I don't see why ANY of these plugins would render a different result with the same settings or sound different.
Old 29th July 2020 | Show parent
  #13
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🎧 10 years
Quote:
Originally Posted by apple-q ➡️
hm, down-mixing is such a simple DSP process (summing signals and sending them to an output) I think ANY plugin (and even no plugin at all) can be used to do this. Just like an MS-XY encode/decode is always the exact came process and same result essentially a sum and difference.

I don't see why ANY of these plugins would render a different result with the same settings or sound different.
This.
If a LoRo downmixer behaves differently it’s broken. It is a really basic process.
The difference in reverbs would be that it’s a non-linear process so cannot cancel completely. Same would happen with dither, as that’s random noise no signals that have dithering applied would cancel to zero but around -60 to -80db dependent on the dither algorithm.
Old 29th July 2020 | Show parent
  #14
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pentagon's Avatar
 
🎧 10 years
Quote:
Originally Posted by Sndnerd ➡️
The ITU preset is actually a net -6 in the centre channel and surrounds I believe.
Net -3.
Not net -6.

Spanner, Avid Downmixer, Nugen all do the same.
Old 29th July 2020 | Show parent
  #15
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Sndnerd's Avatar
 
🎧 5 years
Quote:
Originally Posted by pentagon ➡️
Net -3.
Not net -6.

Spanner, Avid Downmixer, Nugen all do the same.
Right, just saying it comes with an ITU preset that has the trim set at -3, on top of the internal -3 setting. In order to get -3 you need to make sure the trim is set at 0. Or at least that's my understanding from this.
Old 29th July 2020 | Show parent
  #16
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pentagon's Avatar
 
🎧 10 years
Quote:
Originally Posted by Sndnerd ➡️
Right, just saying it comes with an ITU preset that has the trim set at -3, on top of the internal -3 setting. In order to get -3 you need to make sure the trim is set at 0. Or at least that's my understanding from this.
Nope.
The ITU preset in Avid Downmixer shows center at -3 dB but the result is a -3dB per L and R.

The ITU preset of Spanner shows center at 0 dB change with a result of -3dB per L and R.

If you use the presets for both of these plugins and do not change anything, you will get the right result. It is always -3dB for Center as found in Left and Right, -3dB for Ls and Rs in the respective L and R channels, and LFE muted.

As I linked earlier, Netflix is fine with adding LFE in at a low level for their stereo fold down (so not the official ITU fold down)
Old 29th July 2020 | Show parent
  #17
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Sndnerd's Avatar
 
🎧 5 years
Quote:
Originally Posted by pentagon ➡️
Nope.
The ITU preset in Avid Downmixer shows center at -3 dB but the result is a -3dB per L and R.

The ITU preset of Spanner shows center at 0 dB change with a result of -3dB per L and R.

If you use the presets for both of these plugins and do not change anything, you will get the right result. It is always -3dB for Center as found in Left and Right, -3dB for Ls and Rs in the respective L and R channels, and LFE muted.

As I inked earlier, Netflix is fine with adding LFE in at a low level for their stereo fold down (so not the official ITU fold down)
Sorry for the confusion, I was just talking about the Nugen. Understood about the others.
Old 29th July 2020 | Show parent
  #18
Deleted e479b20
Guest
Quote:
Originally Posted by pentagon ➡️
Nope.
The ITU preset in Avid Downmixer shows center at -3 dB but the result is a -3dB per L and R.

The ITU preset of Spanner shows center at 0 dB change with a result of -3dB per L and R.
agree that's because the AVID one is a down-MIXER with no pan pots where all signals are hard patched to the output path and just a fader for level (basically like hard routing each input channel in PT to a stereo out (with no panner) and then setting the levels according to the downmix parameters.
Spanner however is a PANNING-plugin with the earlier mentioned pan-law applied but an ADDITIONAL mixer in there as well.

Both render the same result when used properly just like the "naked" PT mixer would. The only difference is that Spanner is much more flexible and can do all formats unlike the rather limited AVID downmixer that doesn't even support all formats (7.1 to 5.1 for example)

Last edited by Deleted e479b20; 29th July 2020 at 10:04 PM..
Old 5th August 2020
  #19
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TVPostSound's Avatar
 
🎧 10 years
The Avid downmixer, with me, is 0.7 dB hot in ITU 775
Confirmed over 300 episodes!!
Old 2 weeks ago
  #20
Gear Nut
Apologies for the thread necromancy here but since I moved from macOS to Windows the one thing I could not bring along with me was my trusty Spanner which saddens me to no end, and I have taken every opportunity I can to advocate for a Windows version to no avail...

So I purchased the Halo Downmix plugin. The first thing I noticed when activating the Netflix preset on the 5.1 to 2.0 version of the plugin is that my dialog was way too low, which led me to feed some -20dBFS 2KHz tone through both the Avid Downmixer and Halo Downmix with identical settings, specifically the center channel set to -3dB to see if there was any difference and the difference between them was 6dB.

The Avid Downmixer's tone in the 2.0 aux reads -23dB in both channels, while the Halo Downmix's tone reads -29dB!

I'm thinking there has to be something I'm doing wrong or not understanding here like the use of panning law because in my mind there is no way there should be any kind of difference between the two in terms of center channel level. Can someone please tell me what I'm missing here? Screenshot attached.
Attached Thumbnails
Downmixers....-halo-dm-vs-avid-dm.jpg  
Old 2 weeks ago | Show parent
  #21
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pentagon's Avatar
 
🎧 10 years
See posts 15-18 above.
Your center should be at 0 as Nugen applies panning coefficients already whereas Avid Downmixer does not (it just directs signal). The Netflix preset should be just ITU with LFE added.
Old 2 weeks ago | Show parent
  #22
Gear Nut
Even with my center channel at 0 (which is not what the Netflix or ITU presets set it to, they set it to -3), it doesn't match. I currently have the Avid Downmixer's preset set to ITU, and the Halo Downmix's preset set to ITU, and it's the same disparity. I have to set the center channel to +3 to get the same reading the Avid Downmixer gives me at -3.

Which one is wrong?

I'm not quite grasping how the coefficient settings are working either. Changing the Downmix Coefficient center channel value from its default of -3dB up to 0dB doesn't change this level discrepancy at all. Additionally, that setting is recalled by presets, so the there should be nothing wrong with either ITU preset, yet this discrepancy is here.


Last edited by Polyh3dron; 2 weeks ago at 10:00 PM..
Old 2 weeks ago | Show parent
  #23
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pentagon's Avatar
 
🎧 10 years
You haven't changed it. I still see the setting wrong. The "coefficients" are for the input monitoring for comparison. What you need to change is the trim on the C which is what affects your downmix. It is still set at -3 in that picture. It's the little arrow/triangle wedge.
Old 2 weeks ago | Show parent
  #24
Gear Nut
I changed from the Netflix preset to the ITU preset. Those presets are the things that are managing every setting in the plugin. If I manually set the center trim to +3 that's the only way to get an equivalent reading, but selecting the Netflix and ITU presets both bring it back down to -3. So the ITU and Netflix presets in the Halo Downmix plugin are incorrect, yes? With ITU presets on both plugins I should see the same reading.
Old 2 weeks ago
  #25
Gear Head
 
I had this issue when updating Halo Downmix to the latest version. Center channel was 3db lower than it was when using the old version. I had to roll back to 1.2.1.0. Nugen is aware and working on it.

Under normal circumstances, you have the plug-in set correctly.

Do you know which version you are on?
Old 2 weeks ago | Show parent
  #26
Gear Nut
I'm on 1.3.0.6. Guess I need to downgrade?

Funny thing is that I emailed support about this and the response I received was completely incoherent talking about the LFE setting which was 100% irrelevant.

Kind of a nasty bug for a downmixing plugin to have for mission critical deliverable stuff.

EDIT: Just checked Nugen's site and there doesn't seem to be any option to download an older, correctly working version.

Last edited by Polyh3dron; 2 weeks ago at 11:51 PM..
Old 2 weeks ago | Show parent
  #27
Gear Head
 
Log into your account. Go to 'downloads', then, 'build archive'.

Just to be clear, I don't know if this affects new sessions using the new version, or only sessions that were created with an older version and then opened with the new version. I have not tested that yet.
Old 2 weeks ago
  #28
Gear Nut
@ BigSpringSound thanks for your help!

Lo and behold, rolling back to version 1.2.1.0 fixed it, so the latest version of Halo Downmix is severely bugged. Here's the same session I posted the previous screenshot from, completely unchanged, but with Halo Downmix 1.2.1.0 installed:

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