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Audio Specification

• Sound playback in Dancing Onigiri "CW Edition" uses Web Audio API as much as possible to minimize sound playback delay. However, there are cases where the Web Audio API specification does not allow for this. HTML Audio elements are used in some cases.

Patterns that support Web Audio API

• :heavy_check_mark: supported / :x: unsupported (Substitute with HTML Audio)
• To reduce playback delay both locally and remotely, it is faster to encode the music data in base64.

• js, txt format (with encoding) is the data encoded with the music data.
  the Dan-Oni-Js music data conversion tool can create text data encoded with music files.

	mp3, ogg format	js, txt format (with encoding)
Local file (How to open html directly)	:x:	:heavy_check_mark:
Local server (How to set up a server using Xampp)	:heavy_check_mark:	:heavy_check_mark:
Remote server (Uploaded and published on the Web)	:heavy_check_mark:	:heavy_check_mark:

Limitations when using the Audio element in HTML

• HTML Audio is more limited in functionality than the Web Audio API.

• :heavy_check_mark: No issue / :warning: Some functions not available / :x: Not available

	Web Audio API	HTML Audio
Displacement of chart position due to fade-in	:heavy_check_mark:No misalignment	:warning:May be shifted depending on the sound source
Volume setting	:heavy_check_mark:No issue	:heavy_check_mark: (Windows) No issue:x: (Mac / iPad) Always 100%
Fade-in volume	:heavy_check_mark:No issue	:heavy_check_mark: (Windows) No issue:x: (Mac / iPad) No fade-in
Fade-out volume	:heavy_check_mark:No issue	:heavy_check_mark: (Windows) No issue:x: (Mac / iPad) No fade-out
Decimal Adjustment	:heavy_check_mark:valid	:x:invalid

Comparison

Item	AudioPlayer Class	Standard Audio Instance
Internal Implementation	Custom class wrapping Web Audio API's AudioContext/AudioBufferSourceNode	Browser-standard HTMLAudioElement
Target Use	Encoded audio sources (.js/.txt, base64)	Standard audio files (URL specified, unencoded)
Audio Loading	Calls decodeAudioData via init(_arrayBuffer) to decode the buffer	Sets URL to .src and waits for loadedmetadata event
Playback Start	play(_adjustmentTime): Schedules playback by adding g_scheduleLead + adjustment time to AudioContext.currentTime	.play() (Standard API, immediate)
Stop	pause() stops the AudioBufferSourceNode (stop(0)), and close() destroys the node itself	.pause() + resets via removeAttribute('src')/.load()
Seeking (currentTime)	Setting currentTime only updates _fadeinPosition; requires a restart via pause() -> play() to apply	Can seek directly as a native property (also fires timeupdate event)
Elapsed Time Retrieval	elapsedTime getter: Calculated from the difference between AudioContext.currentTime and _scheduledTime (accounting for playbackRate, g_scheduleLead, and fade-in position)	.currentTime (Managed by the browser)
Loop End & Interval Monitoring	Uses a poll function to monitor elapsedTime because the timeupdate event does not fire (repeatBGM)	Determines via timeupdate event when currentTime >= musicEnd
Mute	Custom implementation switching _gain.gain.value between 0 and the saved value (retains volume via _savedVolume)	Native .muted property
Other Interface Compatibility	Provides stub or custom implementations for addEventListener/removeEventListener/load/dispatchEvent, mimicking the Audio interface	Native implementation

Differences in how to start playing on iOS

• In the case of iOS, it is not possible to automatically play a music without user operation. For this reason, a start confirmation button is added just before the start only for iOS.

| < Local storage specification | Audio Specification | Velocity change & Motions > |