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Author Topic: Multi channel audio processing with 2 output channels only  (Read 3455 times)

J-a-k-e

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Multi channel audio processing with 2 output channels only
« on: October 22, 2012, 06:05:52 pm »

I use a dsp plugin by the name of 'Isone Surround 5.1' that does crossfeed and hrtf processing for headphones. This plugin accepts up to 6 channels as an input and outputs stereo left and right only. What is the best way to setup jriver so that I can have a multichannel source that is processed through this plugin that then outputs via my 2 channel usb dac?

The only way I've managed to do this currently is by setting the output mode to directsound otherwise I receive an error when I try to play a multichannel source. Then I have to configure the parametric eq after 'Isone Surround 5.1' in the dsp effect stack to mute all channels but left and right.
This seems to work ok although surely there is a better way to do this?

Up until now I have just used  WASAPI - event style stereo channel output with JRSS mixing. Only I noticed recently I'm not really getting the sound of things behind me, instead mostly everything rear-channel sounds like it's coming from the front.
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mojave

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Re: Multi channel audio processing with 2 output channels only
« Reply #1 on: October 23, 2012, 12:33:47 pm »

I just downloaded and installed the Isone plugin. It does not output stereo left and right only if it receives multichannel input. It even says on the website, "Please note that TB IsoneSurround does not perform any internal stereo-to-surround upmixing. Stereo input will be reproduced on a virtual stereo sound set; multi-channel input will be reproduced on a virtual 5.1 sound set." In other words, stereo stays as stereo and multi-channel stays as multi-channel. However, it reprocesses each to change the original to a "virtual" sound. This is why you are muting other channels. You are actually only processing the front left and right channels.

For best results with headphones, set output to stereo and use JRSS to downmix.

Have you tried using JRiver's own headphone DSP?
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Matt

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Re: Multi channel audio processing with 2 output channels only
« Reply #2 on: October 23, 2012, 01:55:23 pm »

mojave gave a good answer.

There's no way for a third-party DSP to change the number of channels or sample rate.  You can however feed a DSP more channels than you use and let it fill any or all output channels however it likes.

I think downmixing should be faithful to the original mastering with regards to level and timing, and that is what JRSS does.

I suppose a "virtual surround" type downmixer could be interesting, but my personal experience with them has not been favorable.
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Matt Ashland, JRiver Media Center

J-a-k-e

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Re: Multi channel audio processing with 2 output channels only
« Reply #3 on: October 23, 2012, 02:54:46 pm »

"Please note that TB IsoneSurround does not perform any internal stereo-to-surround upmixing. Stereo input will be reproduced on a virtual stereo sound set; multi-channel input will be reproduced on a virtual 5.1 sound set."

Although 'TB Isonesurround' is a newer than 'Isone Surround 5.1' The advanced features, essentially what is present in 'TB Isone' including the ability to precisely calibrate the plugin for your ears and headphones have been stripped from the current version.

Isone Surround 5.1 does in fact have the ability to process a surround input and output this as 2 channel. I can confirm this if I set the channel mode to "Ls, Rs only" with a 5.1 channel input, it sounds like the left rear and right rear channels are playing behind me.
Unfortunately jriver's own JRSS upmixing and headphones DSP to my ears doesn't compare.
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J-a-k-e

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Re: Multi channel audio processing with 2 output channels only
« Reply #4 on: October 23, 2012, 03:33:04 pm »

I suppose a "virtual surround" type downmixer could be interesting, but my personal experience with them has not been favorable.

I know what you mean, bad virtual surround is really bad. I personally can't tolerate the boxy washed out signature that many headphone crossfeed and virtual surround plugins have, dolby headphone included. This plugin isn't just a crossfeed simulator it's a speaker simulator that brings the sound stage out of the head to a more naturally position out in front. For this to work properly the user needs take the time to properly calibrate ear size, head size, and hrtf.

Screenshot here: http://www.head-fi.org/t/473885/isone-pro-the-best-thing-you-could-ever-get-for-your-headphones-on-your-computer/15#post_6494736 the surround version looks exactly the same except for the channel options
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