# Ideal 3D Audio and Video, 3 channels

Discussion in 'Rendering Technology and APIs' started by Kayvan Barin, Jan 24, 2013.

1. ### Kayvan Barin Newcomer

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I had posted an article like this several years ago on this site, but I could not follow the thread at the time. Now I am posting something similiar to that.

As you know, it is presently assumed that 3D effect is picked up by humans because they have 2 eyes and 2 ears. Therefore, we have stereo audio systems and binocular video systems (2 channels). Nowadays for richer content there is a trend of more and more channels for audio. My claim is that a 3 channel system would be the most ideal 3D system that is based on geometry of 3D space which I will explain next. Later I will comment on why we have 2 ears and 2 eyes.

Consider a mono audio system (1 channel). The sound is distributed linearly from speaker to you. Volume and clarity of the sound from speaker is the cue to the position of the object whose sound we are hearing on that line. Now consider a stereo system (2 channels). As well as the object being near or far, it can go right and left too. In other words, the sound is distributed in a plane that is identified by the coordinate plane of 2 axes: one from head to left speaker, and another from your head to right speaker. Now if we have 3 speakers with 3 signals going into them (3 channels), and we put them in a triangular formation in front of us, the sound will have a up and down distribution as well as near and far and left and right. In other words it will occupy a 3D space identified by spacial coordinate system passing through 3 axes: Each one from one speaker to you. I believe 3 channels is the best 3D configuration. Less than 3 channels would be poorer in content. And more than 3 channels will give too many cues, and it will be tiring.

Consider this simple suggestion, when you are watching TV, a stereo sound system just gives you the right and left cue relative to display. But a 3 channel audio system, would give you up and down cue relative to the display too. But more than 3 channels like having a speaker behind you is too much; you would lose the comfort of the living room where you are watching and hearing through the window that is the TV.

Same would apply to 3 channel video. In 2 channel video, you have to keep your head rigid to keep 3D cues intact. But in 3 channel video, tilting your head would give more 3D cues yet.

In optical object recognition systems like Kinect(Microsoftâ€™s user interface for its video game consul), one can detect the most 3D information from 3 cameras in triangular formation. They use Kinect in some methods to measure 3D shape of objects, but they have to move the device along the objects to pick the shape of object calculated from vision through 2 cameras. While it should be available from one snap shot from 3 cameras and less calculations. Also in sound and voice recognition, there may be applications for this configuration.

About having 2 ears and 2 eyes, please remember our head is almost always in motion. If we had an absolutely stationary head, I believe we needed 3 ears and 3 eyes to hear and see in 3D. But since our heads are always moving and the complex brain we have to calculate 3D coordinates based on moving eyes and ears, 2 ears and 2 eyes are enough. May be that 2 ears and 2 eyes were all that evolution could muster so far.

]I do not think we would be able to manage this form of 3D (3 channels) with headphones and glasses as before. Some modification would be necessary. May be 3 stationary speakers and a display that emits lights in 3 directions would be necessary (3D video system without glasses).

Thanks for attention,
Kayvan Barin

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2. ### Davros Legend

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no it wont, have you ever played a game in 5.1 its not tiring in normal life we hear cues from all directions we are used to it.
also your forgetting sound also comes from behind your 3 speaker system(while better than stereo) doesnt account for that

wrong, with headphones we have a stationary head relative to sound source, we still have 3d audio due to htrf, also if you clamped your head so it couldnt move do you really think you'd lose all ability to see in 3d ?

ps: your arguing more speakers = better until we reach 3 then any more = worse ???

http://www.codemasters.com/research/3D_sound_for_3D_games.pdf

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3. ### Kayvan Barin Newcomer

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Yes that is what I mean. I have heard from some people that they prefer 2.1 over 5.1 channels, becuase of too many sound clutter. Also I think the popularity of 2.1 is because it is the closest to 3.0 channels.

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4. ### Davros Legend

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I think the popularity of 2.1 is its cheap and theres less clutter

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5. ### Kayvan Barin Newcomer

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2.1 channel was more expensive than 2.0 channels. But it got adopted by users much more and faster than transition from 2.1 to 5.1. I think 2.1 was offering a more pleasant change than what 5.1 channel is offering, inspite of more expense.

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6. ### Davros Legend

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No 2.1 took off over 2.0 because of the subwoofer. 5.1 means laying cables all over the place and needing somewhere to put the rear speakers thats why some people dont go 5.1 not because 2.1 offers superior audio.

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7. ### Kayvan Barin Newcomer

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I do not know about action and war games, but for something relaxing and pleasant like music I prefer 2.1, and 3.0 would be even better.

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8. ### Arwin Now Officially a Top 10 Poster ModeratorLegend

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Yes, 2.1 took over simply because for desktop speakers, you want relatively small speakers, but for good quality across a large range you need multiple components, of which the ones responsible for 'bass' sounds traditionally require the most space. A relatively cheap solution is to add a subwoofer that stands under the desk, so that you can keep the desk speakers small and only give them (relatively small) decent (or just as often, crappy) high-to-mid frequency components, but still have a considerable 'oomph' coming from below the desk.

For the record, I much prefer a 2.0 set that has a good range all over, because that gives a much better stereo image. I have recently bought a 2.0 desktop speaker set from Bose. Traditionally I'm not a big fan, but I compared a tonne of different sets before I bought that one, and it really was the best sounding one, with a good and balanced range from low to high. 2.1 sets are also a nightmare to balance properly, as the amount of bass you want varies by volume, but these systems rarely have a well-integrated volume control.

Our living room has a 5.0 set as well, for much the same reason. The amount of speakers is only relevant in how much of it you need to be able to create the illusion of where the sound comes from. Rear speakers are essential just for creating a convincing reverb, which helps immensely with creating an illusion of being in a certain space (e.g. parking garage, living room, church, etc.). A classic example for me was the first Speed movie, which used sound very effectively, and which when I first got a surround capable system (one of the first cheap ones, in 1992) I had an opportunity to experience a Laser-disc version of thanks to a friend of a roommate living closeby.

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9. ### Davros Legend

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And 4 would be better still

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10. ### orangpelupa Elite Bug Hunter LegendVeteran

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2.1 ch with great speaker quality combined with decent "surround" mode in software, sounds better than my cheap 4ch speaker (at least for me :/ )

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11. ### Kayvan Barin Newcomer

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Thanks for everybody's responses on 3D audio. How about video? is there any multichannel video available anywhere? I think it is possible to have more than 2 channels with 3D videos that do not use glasses.

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