Audio editing as an exciting topic that involve different knowledge and skills. Whether we are a professional musician or a regular user, sometimes we have to edit an audio file.
There are various audio tools, but my personal focus is on online technology. In general, the online audio tool includes the following areas:
Digital signal processing
Digital audio processing is a sub-field of Digital signal processing. This an interesting topic that appears in life in various forms. The purpose of this process is to extract useful information from the signal. Some common applications are:
- Audio editors
- Voice recognition
- Text to speech
- Sound matching
Like digital image processing, sound processing involves mathematical transformations to analyze or modify the signal.
Web technologies
Unlike native apps, online software depends on available web technologies. Fortunately, modern web standards provide quite useful tools for manipulating and reproducing sound.
WebAssembly
I put WebAssembly (Wasm) first here because I'm a big fan of this technology. It allows all kind of software developers to use the programming language that they love.
I prefer to work with the emscripten compiler tool chain and find it quite convenient for me.
Web Audio API
The Web Audio API is an essential addition to the web standard. It gives ability to manage audio sources, apply sound filters, effects, decode media files and more.
WebWorker
Sometimes our web app has to do some hard work in parallel and keep the UI thread unlocked. In such cases we resort to a working thread, which we start from WebWorker.
One of the frequently mentioned shortcomings of the worker is the lack of DOM access. However, it has access to a large number of common objects such as WebSockets, IndexedDB, Network IO and so on.
AudioWorklet
The AudioWorklet is relatively new addition to the Web Audio API. This tech gives ability to attach a custom JavaScript for audio processing. Like WebWorker, it runs in a dedicated thread to provide low latency during sound manipulation.
Note: This feature works in secure context (HTTPS) on most / all browsers!
WebCodecs API
The WebCodecs API is a recent extension of the web standard. As far as I know, it is currently supported by Google Chrome and Microsoft Edge, but not by Mozilla Firefox.
My experience with this technology is that it works well for video encoding in VP8 and VP9 and OPUS for audio. Unfortunately, there is currently no build-in media muxer. This means that we have to use / write a separate component when we want to export WebM, MKV, MP4 or similar container.
You may read the Video Processing with WebCodecs article for deeper details.
Audio editor for the Web
There are different web applications for audio processing. However, I want to mention the Sound CMD. This free online sound editor is still under development, but there are features that are of interest to me.
- Multi track support - can open multiple files in separate tabs
- Spectrogram viewer, player and editor - Can zoom into sound spectrum to listen (or edit) isolated frequency bands.
- Sound generator - generate signal with different amplitude, phase or shape
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