{howler} - Interactive Audio Player

{howler} is a package that utilises the howler.js library to play audio on the modern web.

Installation

This package is available on CRAN and r-universe. To install the latest version:

install.packages("devtools")
devtools::install_github("ashbaldry/howler")

Usage

The HTML way to include an audio file in any shiny application/web page is to use the <audio> tag. This can generally only handle one audio file, and cannot (easily) be manipulated from the server side.

tags$audio(src = "audio/sound.mp3", type = "audio/mp3", autoplay = NA, controls = NA)

howler.js uses the Web Audio API, and with this we are able to create an audio player that can solve both of the above issues and more:

library(shiny)
library(howler)

ui <- fluidPage(
  title = "howler Example",
  howler(
    elementId = "sound", 
    tracks = list("Track 1" = "audio/track_1.mp3", "Track 2" = "audio/track_2.mp3"),
    auto_continue = TRUE,
    auto_loop = TRUE,
    seek_ping_rate = 1000
  ),
  howlerPreviousButton("sound"),
  howlerPlayPauseButton("sound"),
  howlerNextButton("sound")
)

server <- function(input, output, session) {
  observe({
    req(input$sound_seek)
    if (round(input$sound_seek) == 10) {
      pauseHowl("sound")
    } else if (round(input$sound_seek) == 20) {
      changeTrack("sound", "Track 2")
    }
  })
}

shinyApp(ui, server)

Module

The {howler} package also includes a lightweight module howlerModuleUI and howlerModuleServer that adds a bit of styling to replicate the style of a standard <audio> HTML player.

Examples

All examples are available in the Examples directory and can be run locally by installing the {howler} package:

• Basic Player
• Full Controls
• Module Player
• Server-Side Controls