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  #1  
Old 11-28-2019, 06:10 PM
teklife teklife is offline
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Default Having issues with LtRt downmix

I'm currently downmixing a documentary from 5.1 to LtRt using Neyrinck SoundCode with the PL2 Encoder. (I haven't done this encoding myself before)

The downmix sounds good but I'm not so happy with the decoded 5.1 version.

When decoded, pretty much all the channels are all smeared together a bit. Music is bleeding into the centre from the L and R. Dialog and Narration are bleeding into the LR a bit, and it sounds phasey.

I don't know if this is pretty standard for decoded LtRt or if I'm messing something up.

If not, are there some ways to improve the decoded outcome?
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  #2  
Old 11-30-2019, 02:40 AM
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neilwilkes neilwilkes is offline
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Default Re: Having issues with LtRt downmix

Matrixed surround is always a compromise, and you will never get an Lt/Rt downmix to sound as good as the original 5.1 discrete mix when run through anything, and with DPL II your settings are critical to standing a chance.
Can you please tell me what your DPL II settings are?
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NetStor TurboBox c/w 3x UAD-2 Octo DSP, Steinberg Nuendo 10.2 & Cubase Pro 10.5 c/w WK Audio ID Remote Mixing Console.

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Universal Audio, Plugin Alliance, Eventide, Waves, Sonnox, Zynaptiq, Softube*, iZotope*, Voxengo*, Flux*, Slate Digital*, PSP Audioware* and many more


* = selected tools only (full list available on request)
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  #3  
Old 11-30-2019, 06:48 AM
Cheesehead Cheesehead is offline
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Default Re: Having issues with LtRt downmix

LtRt should be retired IMHO.
It was a technology for a time when bandwidth wasn't available/ allotted for discreet surround channels.
Not only is the decoded signal often unsatisfying in surround, but it also to my ears makes the encoded stereo version lack definition.
It was great and clever for its time.

I don't see it being asked for so much on deliverables any more thankfully.
I hope it will gradually disappear.
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  #4  
Old 11-30-2019, 02:16 PM
teklife teklife is offline
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Default Re: Having issues with LtRt downmix

Quote:
Originally Posted by neilwilkes View Post
Matrixed surround is always a compromise, and you will never get an Lt/Rt downmix to sound as good as the original 5.1 discrete mix when run through anything, and with DPL II your settings are critical to standing a chance.
Can you please tell me what your DPL II settings are?
Ok, thanks for clarifying that. I've since turned down the LSRS in Neyrinck which seems to be helping, The current settings I'm using are:

LR=0 C=-3 LSRS=-6 LFE=-3
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  #5  
Old 12-01-2019, 12:07 PM
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TVPostSound TVPostSound is offline
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Default Re: Having issues with LtRt downmix

Quote:
Originally Posted by Cheesehead View Post
LtRt should be retired IMHO.
It was a technology for a time when bandwidth wasn't available/ allotted for discreet surround channels.
Not only is the decoded signal often unsatisfying in surround, but it also to my ears makes the encoded stereo version lack definition.
It was great and clever for its time.

I don't see it being asked for so much on deliverables any more thankfully.
I hope it will gradually disappear.

No one is asking for LTRT anymore.
Im down mixing LoRo for the 2 channel mix.
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  #6  
Old 12-01-2019, 04:57 PM
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spoons spoons is offline
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Default Re: Having issues with LtRt downmix

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Originally Posted by TVPostSound View Post
No one is asking for LTRT anymore.

Im down mixing LoRo for the 2 channel mix.

Just starting a series for Disney Channel. The abc cable networks spec they sent me still has a LtRt as the 2 channel mix needed along with the 5.1. I queried it but they said it’s required.
Thinking of using the Atmos production suite to make them but there’s no way of listening back to check it.



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  #7  
Old 12-02-2019, 02:02 AM
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neilwilkes neilwilkes is offline
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Default Re: Having issues with LtRt downmix

Quote:
Originally Posted by teklife View Post
Ok, thanks for clarifying that. I've since turned down the LSRS in Neyrinck which seems to be helping, The current settings I'm using are:

LR=0 C=-3 LSRS=-6 LFE=-3
The thing to always bear in mind is that this will always be a compromise. Whilst there is an amount of wishful thinking that it is no longer required, this is not yet the case. Although it is indeed true that the 5.1 specs for HDTV are Dolby Digital, which is discrete (as far as it goes, anyway) plus has it's own downmix metadata it is still a good idea to know how to do this "old school" as only last year I was asked to supply a 5.1 & an LtRt - on DTRS of all things!!

Your settings are very similar to the default setup in a Dolby Digital encoder so should be an acceptable starting point but the only way to know you have it right for your mix is to constantly check, check, check. It's a double compromise too as you first have to compromise your 5.1 mix to a Matrixed Lt/Rt stream & check the decoded version in 5.1 (and this is hard enough) but you also have to compromise your stereo - and for me this was always the biggest problem as it is a serious compromise and a dedicated stereo mix will always sound better (at least to my ears it does).

I can highly recommend the RPGA Surround document as a good start point.
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NetStor TurboBox c/w 3x UAD-2 Octo DSP, Steinberg Nuendo 10.2 & Cubase Pro 10.5 c/w WK Audio ID Remote Mixing Console.

Plug-ins & ancillaries (full libraries unless stated)
AA Translator, GEAR Pro Mastering Edition, Scenarist SD/BD/BD-J, MEI DVD-Audio Creator, DVD-Lab Pro 2
Universal Audio, Plugin Alliance, Eventide, Waves, Sonnox, Zynaptiq, Softube*, iZotope*, Voxengo*, Flux*, Slate Digital*, PSP Audioware* and many more


* = selected tools only (full list available on request)
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  #8  
Old 12-02-2019, 02:41 AM
yanos yanos is offline
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Default Re: Having issues with LtRt downmix

Quote:
Originally Posted by spoons View Post
Just starting a series for Disney Channel. The abc cable networks spec they sent me still has a LtRt as the 2 channel mix needed along with the 5.1. I queried it but they said it’s required.
I was about to write more or less exactly the same thing.
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  #9  
Old 12-02-2019, 07:56 AM
Cheesehead Cheesehead is offline
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Default Re: Having issues with LtRt downmix

Quote:
No one is asking for LTRT anymore.
Im down mixing LoRo for the 2 channel mix.

The last 2 films I did they only asked for stereo so I gave them LoRo because it sounds better. So if you're seeing the same thing we can only hope it will spread out elsewhere?


LoRo usually sounds pretty good decoded to 5.1 anyway.
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  #10  
Old 12-03-2019, 03:08 AM
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neilwilkes neilwilkes is offline
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Default Re: Having issues with LtRt downmix

Quote:
Originally Posted by Cheesehead View Post
The last 2 films I did they only asked for stereo so I gave them LoRo because it sounds better. So if you're seeing the same thing we can only hope it will spread out elsewhere?


LoRo usually sounds pretty good decoded to 5.1 anyway.
A LoRo will only upmix into faux surround - it will not decode because there is nothing to decode.
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XI-machines PC-DAW with Intel Xeon E5-2687W CPU (8/16 cores at 3.1GHz/core), 32GB RAM, AMD Radeon R7 200 Graphics, RME RayDAT I/O > RME ADI-8 DS Pro ADC/DAC, Waves DigiGrid IOS (ethernet), Adam Audio A7x 5.1 system.
NetStor TurboBox c/w 3x UAD-2 Octo DSP, Steinberg Nuendo 10.2 & Cubase Pro 10.5 c/w WK Audio ID Remote Mixing Console.

Plug-ins & ancillaries (full libraries unless stated)
AA Translator, GEAR Pro Mastering Edition, Scenarist SD/BD/BD-J, MEI DVD-Audio Creator, DVD-Lab Pro 2
Universal Audio, Plugin Alliance, Eventide, Waves, Sonnox, Zynaptiq, Softube*, iZotope*, Voxengo*, Flux*, Slate Digital*, PSP Audioware* and many more


* = selected tools only (full list available on request)
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