Base class for audio streams. Base class for audio streams. Audio streams are used for sound effects and music playback, and support WAV (via [AudioStreamWAV]) and Ogg (via [AudioStreamOggVorbis]) file formats. $DOCS_URL/tutorials/audio/audio_streams.html https://godotengine.org/asset-library/asset/526 https://godotengine.org/asset-library/asset/527 https://godotengine.org/asset-library/asset/528 Overridable method. Should return the total number of beats of this audio stream. Used by the engine to determine the position of every beat. Ideally, the returned value should be based off the stream's sample rate ([member AudioStreamWAV.mix_rate], for example). Overridable method. Should return the tempo of this audio stream, in beats per minute (BPM). Used by the engine to determine the position of every beat. Ideally, the returned value should be based off the stream's sample rate ([member AudioStreamWAV.mix_rate], for example). Override this method to customize the returned value of [method get_length]. Should return the length of this audio stream, in seconds. Return the controllable parameters of this stream. This array contains dictionaries with a property info description format (see [method Object.get_property_list]). Additionally, the default value for this parameter must be added tho each dictionary in "default_value" field. Override this method to customize the name assigned to this audio stream. Unused by the engine. Override this method to customize the returned value of [method instantiate_playback]. Should returned a new [AudioStreamPlayback] created when the stream is played (such as by an [AudioStreamPlayer]).. Override this method to customize the returned value of [method is_monophonic]. Should return [code]true[/code] if this audio stream only supports one channel. Returns the length of the audio stream in seconds. Returns a newly created [AudioStreamPlayback] intended to play this audio stream. Useful for when you want to extend [method _instantiate_playback] but call [method instantiate_playback] from an internally held AudioStream subresource. An example of this can be found in the source code for [code]AudioStreamRandomPitch::instantiate_playback[/code]. Returns [code]true[/code] if this audio stream only supports one channel ([i]monophony[/i]), or [code]false[/code] if the audio stream supports two or more channels ([i]polyphony[/i]). Signal to be emitted to notify when the parameter list changed.