AudioFile.scala

package org.chilon.dunny

import java.lang.ProcessBuilder
import java.lang.Process

import java.io.DataInputStream
import java.io.File

class AudioFile(val path: String, val bitRate:Int) {

    if (! new File(path).exists()) throw new Error("sample file does not exist, have you run `make get_resources'?")

    // open a pipe to sox sample.mp3 -t raw -r 44100 -b 32 -e float
    // output.raw and pass it to AudioFileClip
    def clip(offset: Float, length: Float):AudioFileClip = {
        var pb = new ProcessBuilder(
            "sox", path, "-t", "raw", "-r", bitRate.toString,
            "-B", "-e", "float", "-b", "32", "-c", "1", "-", "trim", offset.toString, length.toString)

        var process = pb.start()
        var stream = new DataInputStream(process.getInputStream())
        val nSamples = (bitRate * length).toInt
        var data:Array[Float] = new Array(nSamples)

        try {
            for (i <- 0 to nSamples - 1) {
                data(i) = stream.readFloat()
            }
        }
        catch {
            // the file isn't long enough, the end will be silence
            case e:java.io.EOFException => {
                System.err.println("audio file " + path + " did not contain enough data of provided length at provided offset")
            }
        }

        new AudioFileClip(data, bitRate, length)
    }
}

object AudioFile {
    def apply(p: String, b:Int) = new AudioFile(p, b)
}

class AudioFileClip(val data:Array[Float], val bitRate:Int, l:Float) extends SourceWithLength(l) {

    override def step(time: Float): Float = {
        idx += time
        data(((idx - time) * bitRate).toInt % data.size)
    }
}

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