Fade in and out streaming audio

Panuchka · April 19, 2025, 9:00pm

Hi everyone!

Quick question about the new audioengine now that I’m kind of tackling music stuff… Is there a recommended way to have a fade in/out with the streaming audio? I’m beginning to implement a “jukebox” kind of functionality of changing songs in my game and I wonder if I have to manually just up/lower the volume in the main loop or is there any other way? Thanks in advance <3

Pinging @docEdub a bit

docEdub · April 21, 2025, 4:35pm

This is a good question. Yes, using the main loop is the way to do that right now, but it would be better to do fades at the audio rate, instead. This would be a good feature to add.

Panuchka · April 22, 2025, 9:25am

Would be a cool feature no doubt!

I would imagine using it like:

sound.fadeIn(1000, options)
sound.fadeOut(1000, options)

To get a cross fade…

Dad72 · May 5, 2025, 5:30pm

@docEdub Is this something that exists at the present time:

sound.fadeIn(1000, options)
sound.fadeOut(1000, options)

It would be great to have that. I’m looking to do that in my behavior scripts right now and I’m wondering what exists at the moment or if there are plans to have this soon.

Thank you in advance.

docEdub · May 5, 2025, 5:57pm

No, but soon. I need to do some investigation on what works in different browsers. I know the fade in/out WebAudio functionality is not 100% implemented in Firefox and Chrome on Meta Quest, so I need to go deeper to find the best solution.

docEdub · June 25, 2025, 8:13pm

PR 16781 adds a new setVolume function to sounds and buses that takes options for duration and shape type. Fade in and out can be done using this new function.

The important parts are here:

github.com/BabylonJS/Babylon.js

packages/dev/core/src/AudioV2/abstractAudio/abstractAudioOutNode.ts

364a89479a


      
          /**
           * Sets the audio output volume with optional ramping.
           * If the duration is 0 then the volume is set immediately, otherwise it is ramped to the new value over the given duration using the given shape.
           * If a ramp is already in progress then the volume is not set and an error is thrown.
           * @param value The value to set the volume to.
           * @param options The options to use for ramping the volume change.
           */
          public setVolume(value: number, options: Nullable<Partial<IAudioParameterRampOptions>> = null): void {
              const node = _GetVolumeAudioSubNode(this._subGraph);
              if (!node) {
                  throw new Error("No volume subnode");
              }
          
              node.setVolume(value, options);
          }

github.com/BabylonJS/Babylon.js

packages/dev/core/src/AudioV2/audioParameter.ts

364a89479a


      
          /**
           * Options for ramping an audio parameter's value.
           */
          export interface IAudioParameterRampOptions {
              /**
               * The ramp time, in seconds. Must be greater than 0. Defaults to 0.01 seconds.
               * The audio parameter's value will reach the target value at the end of the duration.
               */
              duration: number;
              /**
               * The shape of the ramp to use for the parameter change. Defaults to {@link AudioParameterRampShape.Linear}.
               */
              shape: AudioParameterRampShape;
          }

github.com/BabylonJS/Babylon.js

packages/dev/core/src/AudioV2/audioParameter.ts

364a89479a


      
          /**
           * The shape of the audio ramp used to set an audio parameter's value, such as a sound's volume.
           */
          export const enum AudioParameterRampShape {
              /**
               * The ramp is linear.
               */
              Linear = "linear",
              /**
               * The ramp is exponential.
               */
              Exponential = "exponential",
              /**
               * The ramp is logarithmic.
               */
              Logarithmic = "logarithmic",
          }

…and the docs will be updated to include setVolume soon!

Dad72 · June 25, 2025, 10:29pm

Wow, that"s great. Thank you very much for this addition. @docEdub

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Fade in and out streaming audio

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