suspend fun download(url: String, progressChannel: SendChannel<Int>) = withContext(Dispatchers.IO) {
    while (true) {
        //read bytes
        progressChannel.send(progress++)
    }
}

fun downloadAudio(url: String) = launch {
    vs.showDownloadProgress()

    val progress = Channel<Int>(UNLIMITED)

    launch {
        download(url, progress)
    }

    for (percent in progress) {
        vs.progress(percent)
    }

    vs.hideDownloadProgress()
}