View Source Print cheatsheet Voice Usage

Playing immediately with a try_play function

def try_play(guild_id, url, type, opts \\ []) do
  case Voice.play(guild_id, url, type, opts) do
    {:error, _msg} ->
      # Wait for handshaking to complete
      Process.sleep(100)
      try_play(guild_id, url, type, opts)

    _ ->
      :ok
  end
end

iex> Voice.join_channel(guild_id, channel_id)
iex> try_play(guild_id, "./song.mp3", :url)

Playing immediately using Nostrum.Voice.ready?/1

def play_when_ready(guild_id, url, type, opts \\ []) do
  if Voice.ready?(guild_id) do
    Voice.play(guild_id, url, type, opts)
  else
    # Wait for handshaking to complete
    Process.sleep(25)
    play_when_ready(guild_id, url, type, opts)
  end
end

iex> Voice.join_channel(guild_id, channel_id)
iex> play_when_ready(guild_id, "https://youtu.be/b4RJ-QGOtw4", :ytdl)

Playing immediately by using events

alias Nostrum.Struct.Event.VoiceReady
alias Nostrum.Voice

def handle_event({:VOICE_READY, %VoiceReady{guild_id: guild_id} = _event, _v_ws_state}) do
  Voice.play(guild_id, "~/loud_noise.mp3", :url, volume: 10)
end

Once the voice handshake has completed, audio will begin playing without the need for polling functions like try_play/4 or play_when_ready/4 as shown in the other examples

iex> Voice.join_channel(guild_id, channel_id)
# Playback will start automatically when ready

Volume

Half volume

Voice.play(guild_id, "~/final_mix.wav", :url, 
  volume: 0.5
)

Extreme clipping

Voice.play(guild_id, "~/boost_this.m4a", :url, 
  volume: 100
)

Normal volume with inverted phase

Voice.play(guild_id, "~/music.mp3", :url, 
  volume: -1.0
)

Start position and duration

Start at 37.8 seconds

Voice.play(guild_id, "https://youtu.be/b4RJ-QGOtw4", :ytdl, 
  start_pos: "0:37.8"
)

Play the first at 15.3 seconds from the beginning

Voice.play(guild_id, "https://youtu.be/b4RJ-QGOtw4", :ytdl, 
  duration: "15.3"
)

Play for 80 seconds (equivalently 1:20) starting from 90 seconds (equivalently 1:30) in

Voice.play(guild_id, "~/music.mp3", :url, 
  start_pos: "90", 
  duration: "80"
)

Advanced audio filtering

Cutoff filters

Low-pass filter at 1200 Hz, high-pass filter at 300 Hz

Voice.play(guild_id, "https://youtu.be/0ngcL_5ekXo", :ytdl,
  filter: "lowpass=f=1200",
  filter: "highpass=f=300"
)

Sample rate

Play at half tempo and pitch (assumes a 48kHz sample rate)

Voice.play(guild_id, "https://youtu.be/0ngcL_5ekXo", :ytdl,
  filter: "asetrate=48000*0.5"
)

Play at 30% higher tempo and pitch. Realtime must be set to false for ffmpeg to keep up with faster-than-normal playback.

Voice.play(guild_id, "https://youtu.be/0ngcL_5ekXo", :ytdl,
  realtime: false,
  filter: "asetrate=48000*1.3"
)

Heavily distorted and effected lo-fi FX chain

Voice.play(guild_id, "https://youtu.be/Hd_giv-wcJU", :ytdl,
  volume: 3,
  start_pos: "0:55",
  filter: "asetrate=48000*0.73",
  filter: "vibrato=d=0.05:f=698.46",
  filter: "vibrato=f=1:d=0.8",
  filter: "lowpass=f=1200",
  filter: "aphaser=in_gain=0.4:out_gain=0.5:delay=3.0:decay=0.3:speed=0.3:type=t"
)