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About Moon Player's Spatial Audio Experience on Apple Vision Pro

2024-03-15 06:47:11

No additional setup is required to play spatial audio in the Moon player. Spatial audio is usually automatically enabled during playback as long as the audio contains Dolby Atmos.

However, it is important to note that if a user turns off system-level spatial audio in Control Center (which is enabled by default), the spatial audio effect will be lost.

To re-enable: First, ensure that Moon Player is playing, and the speakers are playing sound. Then access the control center, long-press the volume bar, and then choose “fixed” or “head tracked” (depending on your preference), as shown in the images below:

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We currently refer to spatial audio generally as the correct decoding of Dolby Atoms.
The Dolby Atoms audio file contains spatial information. Technically speaking, if the decoder is working properly, the user can hear the direction and even the distance of the sound source. For example, an explosion from directly in front and a bird call from the right rear. However, not all players can decode Dolby Atoms correctly. We found during testing that most players on mac could not decode it correctly (you can verify this through the video I sent earlier), only built-in QuickTime can do it.

We generally consider the broad sense of Apple Spatial Audio and Meta Quest Spatial Audio to be a combination of two technologies, one is the correct decoding of Dolby Atoms audio, and the other is spatial playback simulation. The latter plays any audio file (it doesn’t have to be a Dolby Atoms file) in a spatial form through algorithms. The final presentation effect may be different, and even the user can configure it. For example, when the user sets the audio in AVP to Apple Spatial Audio (Fixed), the sound the user hears will have more depth, as if they are at a concert instead of wearing headphones. If the user chooses Apple Spatial Audio (head-tracked), the user will feel that the sound comes from the direction of the window being used. This technology does not change the orientation information of the sound in the audio file itself, only simulates the position where the audio file is played in the real world. So it sometimes even changes the creator’s original intention of the sound (of non-dolby audio), because the simulated location information may disrupt the original location information of the sound.

In addition, many companies are intentionally or unconsciously blurring the lines between these technologies.

Let’s go back to the Moon player. When the user plays a regular audio file (not Dolby Atoms). Apple Spatial Audio takes over this part of the playback. The user can configure it as shown in the picture below.

Choose “off”, the player will not simulate any spatial effects, and the experience the user gets is the same as playing with traditional headphones. Choose “Fixed”, the player will simulate placing several huge high-quality speakers in front of you, and these speakers are “fixed” with the direction of your head, meaning it will rotate with your head. Choose “Head Tracked”, the player will simulate placing several huge high-quality speakers at the position of the playback window, and their position in space remains fixed. No matter how you move, you will find that the sound always comes from the direction of the window.

If the user plays a video with Dolby Atoms, the moon player, in conjunction with the api provided by Apple, can correctly identify and decode it, and then play sounds with spatial recognition. Generally, users do not need to make additional settings, but they can still customize it. If you choose “Head Tracked”, the sound will have a sense of direction, and the sound direction will be fixed relative to the position of the window. This does not mean that the sound must come from the direction of the window, but the angle between the sound direction and the window direction is always fixed. This is usually the most intuitive and the default option provided by Apple. If you choose “fixed”, the sound will still have a sense of direction, but it will be fixed relative to the direction of the user’s head. If the user turns his head, the same sound will also deflect with the direction of the user’s head. If you choose “off”, the spatial effect will be lost and it will become a simple stereo sound, and the layering of the sound will be greatly reduced.