Matrix En/Decoder

These plugins are acting as stereo. In the Insert routing they only get stereo in or out.
Tested them on group channels with 5.1, 5.0 and LRCS out.
I´ve used them on a film two years ago with success.
Does anyone recognise this problem?


I wonder if you’re using them properly - and this is not meant to be a put down, as it has caught me out too.
The Matrix En/Decoder plugins are very specifically for LCRS type (aka DPL) matrix surround, not 5.0 & 5.1 (aka DPLII).
To use the matrix En/Decoders, they need to be set up on an LCRS type buss in the first instance as they only work on 4-channel mixes.

If you need to matrix a 5.0/5.1 mix, then these days MixConvert is your boy unless you have the SurCode DPLII VST plugin.

Thanks for the reply.
I´ve tryed them on LRCS. That was the first thing I did. 6 to 2 works properly, but I´m after the more narrow effect that matrix plugin gives me. Want to make the 5.1 music stems more narrow, since the director liked the LtRt version during the dolby mastering session.
I mixed down in a colleges N5 today. I did the same thing in N4 2 years ago, but then in OS 10.5.
Wher ever I add the plugin. I only get 2 inputs for the encoder and 2 outputs for the decoder.
Anyway I´m having lot´s of troubles with N4 and 10.6.6 and have ordered N5.

Does the mixconvert work the same way?


Hi Perl.

MixConvert will do all you need it to - it really can output properly created Lt/Rt matrix streams with no trouble.
There’s a very detailed set of instructions in the manual (well, the plugin reference one anyway) that explains it better than I can, but suffice to say when I was first told MixConvert can actually do a DPL2 type Lt/Rt I was skeptical, but also wrong.
My only concern with it are the various “hidden” instances where I have no control over it - and watch out for the one in the Control Room too. It will need properly setting up if you use the CR to switch between surround & stereo mixes. It’s accessed by clicking on the little down arrow in the CR, above the visible outputs and below the speaker icons.

Thanks again.

i compared the finalmix made with the Dolbyplugins and it felt as if there where some phase issues whith what I did today in N5. It didn`t have the same center feeling.
The thing is that we rerecorded the certain finalmix passes through the Dolby plugins and then inserted to the opticaldrive. I need to obtain this feeling for the TV mix and the M&E.
Think I´ll give the manual and the convert plugin a chance.

Must add that I am a Pro tool user most od the time. Have mixed a couple of features in Nuendo so far, but not enoughe to be a experienced user.

Per !!!

Not too sure I am understanding what the dolby plugins had phase issues compared to…
If we’re talking about the decoded Lt/Rt streams against the discrete original then this is not too surprising.
The difference in centre feeling could also easily be pan law related - what systems are being compared here please?

Not about hardware differences.

I have a 5.1 mix where the 5.1 music has been processed through the Dolby Pro logic plugins.
Comparing them with the parts I made in N5 gives to me that things happends with the sound when I´m changing listening position much more with the N5 mix than with the PT version.
The thing is the PT version is made in a different studio.
Anyway, thats a minor problem.

BTW. Can it be a Rosetta issue with N5 and the enc/docoder acting in stereo.


Ah - I understand now.
That’s definitely to be expected.
The trouble with matrixed systems is that they are compromises across the board, both in the stereo domain and in the surround one. The stereo is an amalgam of the 5 main channels, of course, with the .1 usually getting discarded in the matrix and reconstituted again at decode and whilst there is much more control over the actual matrixing process in DPL2 compared to the pitiful control on offer in Dolby Digital it is still always going to be a compromise, and likely not anything like as good as a well crafted but dedicated stereo mix would be.
The surround output is even further compromised in the main, because you cannot ever know what decoding algorithm the end user will select. You may have done the original mix with the decoder set to, for sake of example, Movie mode with the panorama controls all bypassed (most likely scenario) yet the end user may equally well have it decoding in Music mode , possibly with altered dimension & centre width settings - or even in Quad mode.

The discrete mix will always sound better, and where possible this is what should be used on the final release too.
Matrix will always be a compromise.

The problem with different decoding presets is an issue for DVD at home I guess. My wish is to make it work in theater decoders. Primary in digtal theaters since it is on optical for the traditional ones.


Won’t work since the Lt_Rt, Matrixed or whateveryouwantocallit “stream” on optical tape is Dolby SR encoded.
Even if you would try to use the theare decoders for edecoding only, you would need to find a way to switch off the Dolby SR decoding too. And believe me, having these SR decoders “on”, while feeding them a non-encoded stream is not a good idea.


The only way DPLII/Lt/Rt matrix works in theatres is in old places where their decoders are not capable of handling a Dolby E discrete output stream.
We recently had this problem, with a documentary release on DVD that also had 2 cinema screenings/previews.
The UK one had to be Stereo LoRo and LtRt (dubbed to DigiBeta) whereas the US one required Dolby E and LoRo backup just in case, again on DigiBeta.

The last optical output we did was DTS Discrete as main, with the Dolby SR Lt/Rt creation on Optical - and it had to go through special boxes too. 4 of them, AIR. 2 LtRt encoders from DTS as well as the Dolby SR.

But if you play a LtRt from disk or tape, then it must not be SR encoded?
I mean you can listen through the decoder in the mixing theater. Or am I on a bicycle tour now? ( Swedish expression)

if your decoding is done in your DVD or other player, then it will be OK.
If you are planning to use the Theatres decoders, then you are screwed.

I mean you can listen through the decoder in the mixing theater.

The Theatre’s decoders are decoding the optical Lt_Rt AND Dolby SR Noise reduction at the same time.
Two solutions:

  1. Feed descrete (decoded) streams to the Theatre’s amps.
  2. Feed Dolby SR encoded Lt_Rt to the Theatre’s Decoders.

FWIW, Dolby now allows short and low budget features to be endoded in SR for free, so if you are planning to do a lot of this stuff, you could look for a second hand Dolby SR encoder. We have one here for this purpose; although not used anymore, since Belgium is 100% DCP.

The standard Dolby setup in a theatre (leaving out DTS and so) is
a) Dolby SRD (Dolby Digital Stream, -much like AC3- located between the perforations)
b) Dolby SR (Analog encoded Lt_Rt on 35mm)

In normal conditions, the audience always hears (or should always hear) the Digital SRD signal.
When the 35mm is worn out -and the SRD stream is lost for some time- the projector switches from SRD to SR.
So the SR is a kind of “safety”. And in theory, the audience shouldn’t notice that switch.

Your only solution will be outputting descrete channels and bypassing the Theatre’s decoders.
Another solution would be DCP, but this requires encoding via a calibrated and expensive encoder.


Thanks for all replys.
Maybe it is not possible to play out an LtRt without it being SR decoded.
Still in a mixing theater it is possible to listen through the surround decoder without SR noicereduction.
In a digital theater there is no need for SR if you want to play a LtRt mix.
Anyway, I,m now working in N5 now and there all plugins work well.


I think you are mistaking. AFAIK, but the SR and Lt_Rt decoding is done in one single decoder. You can’t switch the SR decoding off independantly.

In a digital theater there is no need for SR if you want to play a LtRt mix.

SR is not and can not be Digital.
The SRD stream is digital, and is located between the perforations.
The SR stream is always analog.
So when the digital SRD streams drops away, because the 35mm is worn out by frequent playing, the projector swicthes right away to the ANALOG SR stream.

SRD and SR are encoded at the same time at the Dolby stage.
So -for theatre/35mm- there simply is no Lt_Rt without SR encoding.