v0.6.0

Kira v0.6 is a complete rewrite of Kira with the following goals:

• Make the API more elegant
• Make the library leaner by removing features that weren't pulling their weight
• Provide a solid technical foundation for future feature development

Of course, the overall goals of Kira are the same: provide a library that fills missing niches in most audio libraries and enables people to be creative with their game audio.

Streaming sounds

Kira now supports streaming sounds! Unlike static sounds, which keep all audio data in memory, streaming sounds decode audio from the filesystem in realtime. This has a much leaner memory footprint at the cost of higher CPU usage.

The Sound trait

Static and streaming sounds are both implementors of the new Sound trait. Sounds produce arbitrary streams of audio, so they can be used for both finite sounds or infinite sounds, like voice chat audio. In this sense, they're similar to AudioStreams from previous versions of Kira, but they can be automatically unloaded when they're finished, and they can receive clock events (see below). They're better integrated with the rest of Kira, making them first class citizens instead of escape hatches.

Kira no longer has any concept of "instances". If you want to play a static sound multiple times, you can clone it each time you want to pass it to AudioManager::play. (Static sounds share their samples via an Arc, so cloning is cheap.) Streaming sounds cannot be cloned since each one opens up a new file handle.

Clocks

Metronomes and sequences from previous versions of Kira were useful for complex audio scripting, but most games don't need such a complex system. In Kira v0.6, they're both replaced by clocks, which are simple timing sources.

Static and streaming sounds can be set to start playing at a certain clock time. Additionally, tweens can be set to start at a clock time. This means anything involving a tween, such as fading out a sound or changing its playback rate, can be synced to a clock.

If you need a more complex system, you should be able to build it in gameplay code using clocks as a building block.

More flexible mixer routing

The mixer no longer makes a distinction between sub-tracks and send tracks. Any sub-track can be routed to any number of other sub-tracks.

Modular backends

Previous versions of Kira were hardcoded to use cpal to talk to the operation system's audio drivers. Kira v0.6.0 has a Backend trait, so you can implement your own backends.

More permissive licensing

Kira is now available under the MIT or Apache-2.0 license. (Previous versions were only available under MIT.)

Feature removals

Parameters

Previous versions of Kira had global "parameters" that you could link settings to, like metronome tempos and instance playback rates. The only way to smoothly tween a setting was to link it to a parameter and tween that parameter. It is useful to be able to link multiple settings to one parameter, but the more common use case was to create a parameter just to tween one setting, which isn't very ergonomic.

In Kira v0.6, parameters have been removed, and all settings can be tweened directly. In future versions, I'd like to bring back global parameters and allow users to either tween settings directly or link them to parameters, I just haven't figured out a good way to architect that.

Arrangements

The main purpose of arrangements was to make it easier to create looping music with intro sections. It served that purpose well, but it was overkill for that purpose, and it wouldn't work with streaming sounds.

Groups

Groups were meant to help with pausing, resuming, stopping, and unloading large categories of resources. It tried to cover different types of resources with different notions of pausing, resuming, and stopping. It mapped decently to instances and sequences, but I think it would have been likely that future versions of Kira would have a resource type that groups didn't make sense for, and the abstraction would become shakier over time. Furthermore, resource management can be done from gameplay code, so it's not even necessary for Kira to provide this feature.

Changes since v0.6.0 beta 6

• Added volume control and panning control effects
• Removed the built-in panning control from mixer tracks