Since we will be animating this visualisation, we'll call upon the browser's requestAnimationFrame API to pull the latest audio data from the AnalyserNode everytime we want to update the visualisation. To do this, we'll create a method that will be called every time requestAnimationFrame runs. The function will copy the current waveform as an array of integers, from the AnalyserNode into the dataArray. It will then update the audioData property in the component's state with the dataArray. Finally, it will call on requestAnimationFrame again to request the next update.
We kick off the animation loop from the end of the componentDidMount method after we connect the source to the analyser. We'll initialise the state of the component in the constructor, with an empty Uint8Array and also bind the scope of the tick function to the component. One other thing we want to do is release all the resources if we remove the component. Create a componentWillUnmount method that cancels the animation frame and disconnects the audio nodes. We haven't rendered anything from this component yet.
We can take a look at the data that we're producing. Add a render method to the component with the following:. Looking at a bunch of numbers updating is no fun though, so let's add a new component to visualise this data. Let's start this class with the render method. In the constructor create the reference using React. Let's build a function that will draw a waveform on the canvas. The idea is to take the audioData we created in the previous component and draw a line from left to right between each data point in the array.
Start with a new function called draw. This function will be called each time we get new data from the analyser. We start by setting up the variables we want to use:. Now we start to work to build up the picture we're going to draw on the canvas. First setting our drawing style, in this case setting a line width of 2 and stroke style to the colour black. Then we clear previous drawings from the canvas. Next, begin the path we are going to draw and move the drawing position to halfway down the left side of the canvas.
Loop over the data in audioData. Each data point is between 0 and To normalise this to our canvas we divide by and then multiply by the height of the canvas. We then draw a line from the previous point to this one and increment x by the sliceWidth.
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Finally we draw a line to the point halfway down the right side of the canvas and direct the canvas to colour the entire path. The draw function needs to run every time the audioData is updated.
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Add the following function to the component:. And we're done. Click the button, make some noise, and watch the visualiser come to life. In this post we've seen how to get access to the microphone, setup the Web Audio API to analyse audio and visualise it on a canvas, splitting up the job between two React components.
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We can use this as a basis to create more interesting and creative visualisations. Alternatively, if you're creating a video chat in React , you could add this visualisation to show who's making noise on the call, or even to check if your own microphone is working. You can check out all the code to this application on GitHub.
I'd love to see what other visualisations you can create, if you come up with something let me know in the comments or on Twitter at philnash. Download Now.
Log In Sign Up Close. Use Cases. Enlarge cover. Error rating book. Refresh and try again. Open Preview See a Problem? Details if other :. Thanks for telling us about the problem. Return to Book Page. Jung-Woo Choi. Unique in addressing two different problems - sound visualization and manipulation - in a unified way Advances in signal processing technology are enabling ever more accurate visualization of existing sound fields and precisely defined sound field production. The idea of explaining both the problem of sound visualization and the problem of the manipulation of sound within Unique in addressing two different problems - sound visualization and manipulation - in a unified way Advances in signal processing technology are enabling ever more accurate visualization of existing sound fields and precisely defined sound field production.
The idea of explaining both the problem of sound visualization and the problem of the manipulation of sound within one book supports this inter-related area of study. With rapid development of array technologies, it is possible to do much in terms of visualization and manipulation, among other technologies involved with the spatial distribution of sound. This book aims to explore various basic functions for the visualization and manipulation and demonstrate to the reader how these properties determine the quality of visualization and manipulation.
The first half of the book introduces some basic and general concepts and theories and the second part of the book explains a number of techniques in sound visualization and manipulation. It offers a unified presentation to two very different topics - sound field visualization techniques based on microphone arrays, and techniques for generation of controlled sound fields using loudspeaker arrays.
The authors emphasize the similarities between these two physical problems and between the mathematical methods used for solving them. Get A Copy. Hardcover , pages. Published December 9th by Wiley first published January 1st More Details Other Editions 5. Friend Reviews.
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