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An Audio Analogy

Primer: The Principles Of 3D Video And Blu-ray 3D

3D video is similar in many ways to surround sound. Just as surround sound adds depth, placing you in the middle of the performance, 3D video places you, the viewer, in the action.

Just as we see the world with two eyes, we hear the world with two ears. Binaural hearing lets us sense the direction from which sounds are coming. Your brain processes the sounds detected by both of your ears. Without thinking, your brain will sense the difference in the time that the sound arrives at each ear, and the difference in the volume of the sound that each ear detected and you will have a sense for the direction that the sound came from. Our three-dimensional vision is similar to our three-dimensional hearing. We don’t have to think about the differences in the picture that each eye sees; we just sense the relative distance of everything we see.

When sound recording was first developed, each recording contained only a single channel of audio. Monaural recordings were later improved with two-channel stereo recordings. Two channels of audio provide an added dimension with respect to the apparent location of the source of each sound that is mixed into the recording. This “sound stage” allows recording engineers to arrange the relative position of instruments in a band, from left to right. When played back through a stereo amplifier and stereo speakers, the listener can hear a difference in relative volume coming from each speaker, and the relative timing of the sound for each instrument or voice. These differences give our brains an audible clue that helps us sense where the sound is coming from.

With a stereo recording, all of the sound appears to come from one general direction: the direction of the speakers. This is fine for reproducing music, as we are used to music coming from the direction we are facing when we attend a live music performance. Movies producers want their audience to feel that they are at the location that the movie is happening (in the room, or at the scene). To give the audience the feel of “being there”, multi-channel surround sound was developed. 

Just as surround sound systems provide a more immersive experience, 3D video adds an important third dimension to movies and television. 

Done well, 3D video provides an experience that feels real and natural. Clearly, audiences are excited by the experience, and they have shown a strong preference for seeing 3D movies in 3D cinemas.

If you'd like to download this primer in PDF format, CyberLink is making it freely available on its site.

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