multiple audio3d listeners

[david_ragazzi]

I find out that that have multiple listeners in Panda3d is possible bypassing the default 3D audio manager and creating your own manager using the FMOD library (through python bindings) as suggested earlier. With it you can easily create a Sound object and one or more Listener objects, pass their respective positions and velocities and then get 3d sound reaching all listeners. However… according to FMOD documentation (https://www.fmod.org/docs/content/generated/overview/3dsound.html), effects like doppler and others are disabled to avoid confusion which makes multiple listeners less attractive (at least to me):

Split screen / multiple listeners

In some games, there may be a split screen mode. When it comes to audio, this means that FMOD Studio has to know about having more than 1 listener on the screen at once. This is easily handled via System::set3DNumListeners and System::set3DListenerAttributes.

If you have 2 player split screen, then for each ‘camera’ or ‘listener’ simply call System::set3DListenerAttributes with 0 as the listener number of the first camera, and 1 for the listener number of the second camera. System::set3DNumListeners would be set to 2.

When using the low-level, 3D channels have the following behaviour:

- It turns off all doppler. This is because one listener might be going towards the sound, and another listener might be going away from the sound. To avoid confusion, the doppler is simply turned off.
- All audio is mono. If to one listener the sound should be coming out of the left speaker, and to another listener it should be coming out of the right speaker, there will be a conflict, and more confusion, so all sounds are simply panned to the middle. This removes confusion.
- Each sound is played only once as it would with a single player game, saving voice and cpu resources. This means the sound's effective audibility is determined by the closest listener to the sound. This makes sense as the sound should be the loudest to the nearest listener. Any listeners that are further away wouldn't have any impact on the volume at this point.

I upload some example about how use FMOD in python here:

[SOLVED] Get actual sounds listened by one or more listeners

To whom may interest… Finally I managed to get the spectrum of the actual 3D sound reaching each ear! For this I had to use directly the FMOD library through pyfmodex (https://github.com/tyrylu/pyfmodex/tree/master/pyfmodex) - a very nice python bindings to FMOD library. The code bellow is an example showing in real-time the 3D panning of a sound passing in front of your head from left to right and then from rigth to left. You will note that when the sound is going to the left side, the bars of…

Of if you don’t care about spectrums, this is simpler:

import sys
import time
import pyfmodex
from pyfmodex.constants import FMOD_SOFTWARE, FMOD_LOOP_NORMAL, FMOD_3D

if __name__ == '__main__':

    def change_listener(listener):
        current_listener.position = listener
        fmod.update()

    ## FMOD initialization
    fmod = pyfmodex.System()
    fmod.init()

    ## Load the sound
    sound1 = fmod.create_sound("sine.wav",
                               mode=FMOD_LOOP_NORMAL | FMOD_3D | FMOD_SOFTWARE)

    ## Play the sound
    channel = sound1.play()
    channel.volume = 0.7
    channel.min_distance = 50
    channel.max_distance = 10000  ## Need this for sound fall off

    ## Create listeners positions
   listener1 = (0, 0, 0)
   listener2 = (0, 10, 0)

    ## Create a FMOD listener in the center of the scene
    current_listener = fmod.listener(id=0)
    change_listener(listener1)

    ## Walk the sound around your head
    min_x = -30
    max_x = 30
    sound_pos = (max_x, 3, 0)
    x = min_x
    inc = 1
    while True:
        if x == min_x:
            inc = 1
        elif x == max_x:
            inc = -1
        x += inc
        channel.position = [x, sound_pos[1], sound_pos[2]]
        fmod.update()
        print("Playing at %r" % str(channel.position))
        time.sleep(0.1)

Put your headphones, run the code above and enjoy…

PS:

In this case, you still have a single listener, not multiple listeners hearing at same time. The difference is that you can change which user will hear…

Yes, I created the function change_listener to fill this role.