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Out of phase intensity stereo
Neuron
post Jul 21 2014, 20:56
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This thread has been long dead, but I'd still really like to know, how does Opus intensity stereo invert phase without cancelation effects?
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jmvalin
post Jul 22 2014, 04:15
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QUOTE (Neuron @ Jul 21 2014, 15:56) *
This thread has been long dead, but I'd still really like to know, how does Opus intensity stereo invert phase without cancelation effects?


When at does is that it's allowed (not forced) to have right be 180 out of phase with left when the encoder thinks its a good idea. You don't get cancellation unless you actually decide to downmix to mono, in which case the cancellation you get depends on the relative intensity of left vs right (you get perfect cancellation of a band if it has equal intensity in left and right).
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wswartzendruber
post Sep 5 2014, 04:56
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QUOTE (jmvalin @ Jul 21 2014, 23:15) *
When at does is that it's allowed (not forced) to have right be 180 out of phase with left when the encoder thinks its a good idea. You don't get cancellation unless you actually decide to downmix to mono, in which case the cancellation you get depends on the relative intensity of left vs right (you get perfect cancellation of a band if it has equal intensity in left and right).

I wonder if this is why it tends to wreak havoc on surround matrix decoders.
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Garf
post Sep 5 2014, 10:15
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QUOTE (wswartzendruber @ Sep 5 2014, 05:56) *
I wonder if this is why it tends to wreak havoc on surround matrix decoders.


What does "it" mean in that sentence and what have surround decoders got to do with "it"? He's talking about downmixing to mono, which is quite obviously not relevant to surround decoders.
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jmvalin
post Sep 6 2014, 06:55
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QUOTE (Garf @ Sep 5 2014, 05:15) *
What does "it" mean in that sentence and what have surround decoders got to do with "it"? He's talking about downmixing to mono, which is quite obviously not relevant to surround decoders.


Well, when surround decoders add/subtract channels, then intensity stereo in general (not just from Opus) has a potential for creating artefacts. I guess mixing Opus 180-degree may add to that too.
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Woodinville
post Nov 10 2014, 02:39
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"Surround Sound" decoders are going to take the sum of the two channels for the center channel, just like adding the two channels gets you mono.

So the effects in one can be much like the effects in the other.


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