Filter :soundfont argument in start_link and pass to MIDISynth

Pass start_link arguments to MIDISynth
Simplify event creation

.gitignore

@@ -20,5 +20,5 @@ erl_crash.dump
 *.ez
 
 # Ignore package tarball (built via "mix hex.build").
-midi_tools-*.tar
+midi_player-*.tar
 

LICENSE

@@ -0,0 +1,674 @@
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+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.

README.md

@@ -1,21 +1,74 @@
-# MIDITools
+# MIDIPlayer
 
-**TODO: Add description**
+A MIDI player for Elixir.
 
-## Installation
+## Prerequisites
 
-If [available in Hex](https://hex.pm/docs/publish), the package can be installed
+Install FluidSynth to play MIDI commands:
-by adding `midi_tools` to your list of dependencies in `mix.exs`:
 
-```elixir
+On Linux:
-def deps do
+
-  [
+```sh
-    {:midi_tools, "~> 0.1.0"}
+sudo apt install libfluidsynth-dev
-  ]
-end
 ```
 
-Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)
+On OSX:
-and published on [HexDocs](https://hexdocs.pm). Once published, the docs can
-be found at [https://hexdocs.pm/midi_tools](https://hexdocs.pm/midi_tools).
 
+```sh
+brew install fluidsynth
+```
+
+Clone this repo or put the [Hex dependency](https://hex.pm/packages/midi_player) in your mix.exs:
+
+```elixir
+{:midi_player, "~> 0.2.0"}
+```
+
+## Examples
+
+MIDIPlayer takes "events" which for example represent to play a note for a time span.
+It then converts these events to MIDI commands and schedules them.
+
+First, let's create some events.
+This plays a piano sound for the C note for 1 second:
+
+```elixir
+iex> piano = MIDIPlayer.Event.note(0, 60, 0, 1000, 127)
+```
+
+We can change the instrument to a violin after one second like so:
+
+```elixir
+iex> change = MIDIPlayer.Event.change_program(0, 1000, 41)
+```
+
+(Note that it could be simpler to use another MIDI channel for another instrument.)
+
+Finally, play two notes on the violin at the same time:
+
+```elixir
+iex> violin1 = MIDIPlayer.Event.note(0, 67, 1000, 3000, 127)
+iex> violin2 = MIDIPlayer.Event.note(0, 64, 1000, 3000, 127)
+```
+
+Now we are ready to play these events.
+First start the player like so:
+
+```elixir
+iex> {:ok, player} = MIDIPlayer.start_link()
+```
+
+Then load the events, and play them!
+
+```elixir
+iex> MIDIPlayer.generate_schedule(player, [piano, change, violin1, violin2], 3000)
+iex> MIDIPlayer.play(player)
+```
+
+## Thanks
+
+This project uses [MIDISynth](https://github.com/fhunleth/midi_synth)
+for generating MIDI commands and operating the FluidSynth synthesizer.
+It also uses [Timex](https://github.com/bitwalker/timex)
+for timing related functionality.
+Inspiration from [Beats](https://github.com/mtrudel/beats).

lib/midi_player.ex

@@ -1,18 +1,29 @@
-defmodule MIDITools.Player do
+defmodule MIDIPlayer do
   use GenServer
 
   @moduledoc """
   A GenServer for playing a schedule of MIDI commands at predefined times.
   """
 
+  # TBD: I think cancelling the timer could introduce a race condition.
+  # Could maybe match timer's reference to saved one?
+
+  @type schedule :: [{non_neg_integer(), binary()}]
+
   # Client API
 
+  @midi_synth_args [:soundfont]
+
   @doc """
   Start the MIDI player.
+
+  The soundfont path can be set with the :soundfont argument.
   """
-  @spec start_link() :: GenServer.on_start()
+  @spec start_link(GenServer.options()) :: GenServer.on_start()
-  def start_link do
+  def start_link(opts \\ []) do
-    GenServer.start_link(__MODULE__, nil, name: __MODULE__)
+    init_args = Keyword.take(opts, @midi_synth_args)
+    server_args = Keyword.drop(opts, @midi_synth_args)
+    GenServer.start_link(__MODULE__, init_args, server_args)
   end
 
   @doc """
@@ -24,58 +35,72 @@ defmodule MIDITools.Player do
   The duration makes sure the player plays a (potential) pause after the last
   midi command.
 
-  See `MIDITools.Event` to create events.
+  See `MIDIPlayer.Event` to create events.
   """
-  @spec generate_schedule([MIDITools.Event.t()], non_neg_integer()) :: :ok
+  @spec generate_schedule(GenServer.server(), [MIDIPlayer.Event.t()], non_neg_integer()) :: :ok
-  def generate_schedule(events, duration) when duration > 0 do
+  def generate_schedule(player, events, duration) when duration > 0 do
-    GenServer.call(__MODULE__, {:generate_schedule, events, duration})
+    GenServer.call(player, {:generate_schedule, events, duration})
   end
 
   @doc """
   Play the current MIDI schedule from the start.
   """
-  @spec play() :: :ok
+  @spec play(GenServer.server()) :: :ok
-  def play do
+  def play(player) do
-    GenServer.call(__MODULE__, :play)
+    GenServer.call(player, :play)
   end
 
   @doc """
   Set the player on repeat or not.
   """
-  @spec set_repeat(boolean()) :: :ok
+  @spec set_repeat(GenServer.server(), boolean()) :: :ok
-  def set_repeat(repeat) when is_boolean(repeat) do
+  def set_repeat(player, repeat) when is_boolean(repeat) do
-    GenServer.call(__MODULE__, {:set_repeat, repeat})
+    GenServer.call(player, {:set_repeat, repeat})
   end
 
   @doc """
   Stop the player and cancel the pause.
   """
-  @spec stop_playing() :: :ok
+  @spec stop_playing(GenServer.server()) :: :ok
-  def stop_playing do
+  def stop_playing(player) do
-    GenServer.call(__MODULE__, :stop_playing)
+    GenServer.call(player, :stop_playing)
   end
 
   @doc """
-  Pause the player. See `MIDITools.Player.resume/0` for resuming playback.
+  Pause the player.
+
+  See `MIDIPlayer.resume/1` for resuming playback.
   """
-  @spec pause() :: :ok | {:error, :already_paused | :not_started}
+  @spec pause(GenServer.server()) :: :ok | {:error, :already_paused | :not_started}
-  def pause do
+  def pause(player) do
-    GenServer.call(__MODULE__, :pause)
+    GenServer.call(player, :pause)
   end
 
   @doc """
   Resume playback on the player after it has been paused.
   """
-  @spec resume() :: :ok, {:error, :not_paused}
+  @spec resume(GenServer.server()) :: :ok | {:error, :not_paused}
-  def resume do
+  def resume(player) do
-    GenServer.call(__MODULE__, :resume)
+    GenServer.call(player, :resume)
+  end
+
+  @doc """
+  Get the current schedule of the player.
+
+  The schedule is a list of tuples of a time in milliseconds and the
+  corresponding bitstream of MIDI commands to be played at that time.
+  The list is guaranteed to be ascending in time.
+  """
+  @spec get_schedule(GenServer.server()) :: schedule()
+  def get_schedule(player) do
+    GenServer.call(player, :get_schedule)
   end
 
   # Server callbacks
 
   @impl GenServer
-  def init(_arg) do
+  def init(args) do
-    {:ok, synth} = MIDISynth.start_link([])
+    {:ok, synth} = MIDISynth.start_link(args)
 
     {:ok,
      %{
@@ -100,15 +125,14 @@ defmodule MIDITools.Player do
     start_time = Timex.now()
     timer = start_timer(schedule, start_time)
 
-    {:reply, :ok,
+    {:reply, :ok, %{reset(state) | timer: timer, start_time: start_time}}
-     %{reset(state) | timer: timer, start_time: start_time}}
   end
 
   def handle_call({:set_repeat, repeat}, _from, state) do
     {:reply, :ok, %{state | repeat: repeat}}
   end
 
-  def handle_call(:stop_playing, _from,  state) do
+  def handle_call(:stop_playing, _from, state) do
     {:reply, :ok, reset(state)}
   end
 
@@ -143,6 +167,10 @@ defmodule MIDITools.Player do
     {:reply, :ok, %{state | timer: timer, start_time: start_time, pause_time: nil}}
   end
 
+  def handle_call(:get_schedule, _from, %{schedule: schedule} = state) do
+    {:reply, schedule, state}
+  end
+
   @impl GenServer
   def handle_info(
         :play,
@@ -210,7 +238,7 @@ defmodule MIDITools.Player do
 
   defp convert_events(events) do
     events
-    |> Enum.flat_map(&MIDITools.Event.convert/1)
+    |> Enum.flat_map(&MIDIPlayer.Event.convert/1)
     |> Enum.reduce(%{}, fn {time, midi}, acc ->
       Map.update(acc, time, midi, &<<&1::binary, midi::binary>>)
     end)

lib/midi_player/event.ex

@@ -1,6 +1,7 @@
-defmodule MIDITools.Event do
+defmodule MIDIPlayer.Event do
   @moduledoc """
   Several musical events which can be converted to MIDI commands.
+
   All timings are in milliseconds.
   """
 
@@ -10,17 +11,6 @@ defmodule MIDITools.Event do
     """
 
     defstruct channel: 0, tone: 0, start_time: 0, end_time: 0, velocity: 0
-
-    @spec new(MIDISynth.Command.channel(), non_neg_integer(), non_neg_integer(), non_neg_integer(), MIDISynth.Command.velocity()) :: %Note{}
-    def new(channel, tone, start_time, end_time, velocity) when start_time >= 0 and end_time > start_time do
-      %__MODULE__{
-        channel: channel,
-        tone: tone,
-        start_time: start_time,
-        end_time: end_time,
-        velocity: velocity
-      }
-    end
   end
 
   defmodule ChangeProgram do
@@ -29,11 +19,6 @@ defmodule MIDITools.Event do
     """
 
     defstruct channel: 0, time: 0, program: 0
-
-    @spec new(MIDISynth.Command.channel(), non_neg_integer(), non_neg_integer()) :: %ChangeProgram{}
-    def new(channel, time, program) do
-      %__MODULE__{channel: channel, time: time, program: program}
-    end
   end
 
   @typedoc """
@@ -41,6 +26,30 @@ defmodule MIDITools.Event do
   """
   @type t :: %Note{} | %ChangeProgram{}
 
+  @spec note(
+          MIDISynth.Command.channel(),
+          non_neg_integer(),
+          non_neg_integer(),
+          non_neg_integer(),
+          MIDISynth.Command.velocity()
+        ) :: %Note{}
+  def note(channel, tone, start_time, end_time, velocity)
+      when start_time >= 0 and end_time > start_time do
+    %Note{
+      channel: channel,
+      tone: tone,
+      start_time: start_time,
+      end_time: end_time,
+      velocity: velocity
+    }
+  end
+
+  @spec change_program(MIDISynth.Command.channel(), non_neg_integer(), non_neg_integer()) ::
+          %ChangeProgram{}
+  def change_program(channel, time, program) do
+    %ChangeProgram{channel: channel, time: time, program: program}
+  end
+
   @doc """
   Converts the event to a list of MIDI commands.
   """

lib/midi_tools.ex

@@ -1,18 +0,0 @@
-defmodule MIDITools do
-  @moduledoc """
-  Documentation for `MIDITools`.
-  """
-
-  @doc """
-  Hello world.
-
-  ## Examples
-
-      iex> MIDITools.hello()
-      :world
-
-  """
-  def hello do
-    :world
-  end
-end

mix.exs

@@ -1,21 +1,26 @@
-defmodule MIDITools.MixProject do
+defmodule MIDIPlayer.MixProject do
   use Mix.Project
 
   def project do
     [
-      app: :midi_tools,
+      app: :midi_player,
-      version: "0.1.0",
+      version: "0.2.0",
       elixir: "~> 1.10",
       start_permanent: Mix.env() == :prod,
       deps: deps(),
 
       # Docs
-      name: "MIDITools",
+      name: "MIDIPlayer",
-      source_url: "https://github.com/pizzapim/midi_tools",
+      source_url: "https://github.com/pizzapim/midi_player",
-      homepage_url: "https://github.com/pizzapim/midi_tools",
+      homepage_url: "https://github.com/pizzapim/midi_player",
       docs: [
-        main: "MIDITools"
+        extras: ["README.md"],
-      ]
+        main: "readme"
+      ],
+
+      # Hex stuff
+      description: description(),
+      package: package()
     ]
   end
 
@@ -25,11 +30,26 @@ defmodule MIDITools.MixProject do
     ]
   end
 
+  defp description do
+    """
+    A MIDI player for Elixir.
+    MIDIPlayer takes musical "events" like playing a note, converts them to MIDI commands, schedules them and then lets you play them.
+    """
+  end
+
+  defp package do
+    [
+      name: "midi_player",
+      licenses: ["GPL-3.0-or-later"],
+      links: %{"GitHub" => "https://github.com/pizzapim/midi_player"}
+    ]
+  end
+
   defp deps do
     [
       {:midi_synth, "~> 0.4.0"},
       {:timex, "~> 3.6"},
-      {:ex_doc, "~> 0.22", only: :dev, runtime: false},
+      {:ex_doc, "~> 0.22", only: :dev, runtime: false}
     ]
   end
 end

test/event_test.exs

@@ -0,0 +1,27 @@
+defmodule MIDIPlayer.EventTest do
+  use ExUnit.Case
+  doctest MIDIPlayer.Event
+
+  alias MIDIPlayer.Event
+
+  test "note event" do
+    assert %Event.Note{channel: 0, tone: 60, start_time: 1, end_time: 1000, velocity: 127} =
+             Event.note(0, 60, 1, 1000, 127)
+  end
+
+  test "change program event" do
+    assert %Event.ChangeProgram{channel: 0, time: 1, program: 40} = Event.change_program(0, 1, 40)
+  end
+
+  test "note event conversion" do
+    note = Event.note(0, 60, 1, 1000, 127)
+    [note_on, note_off] = Event.convert(note)
+    assert {1, <<0x90, 60, 127>>} = note_on
+    assert {1000, <<0x80, 60, 64>>} = note_off
+  end
+
+  test "change program event conversion" do
+    change_program = Event.change_program(0, 1, 40)
+    assert [{1, <<0xC0, 40>>}] = Event.convert(change_program)
+  end
+end

test/midi_tools_test.exs

@@ -1,8 +0,0 @@
-defmodule MIDIToolsTest do
-  use ExUnit.Case
-  doctest MIDITools
-
-  test "greets the world" do
-    assert MIDITools.hello() == :world
-  end
-end

test/player_test.exs

@@ -0,0 +1,59 @@
+defmodule MIDIPlayerTest do
+  use ExUnit.Case
+  doctest MIDIPlayer
+
+  alias MIDIPlayer, as: Player
+  alias MIDIPlayer.Event
+
+  setup do
+    {:ok, player} = Player.start_link([])
+    [player: player]
+  end
+
+  setup_all do
+    events = Enum.map(1..4, &Event.note(9, 51, &1 * 500, (&1 + 1) * 500, 127))
+    duration = 2000
+    [events: events, duration: duration]
+  end
+
+  test "play", %{player: player, events: events, duration: duration} do
+    assert :ok = Player.generate_schedule(player, events, duration)
+    assert :ok = Player.play(player)
+    Process.sleep(2500)
+  end
+
+  test "pause & resume", %{player: player, events: events, duration: duration} do
+    Player.generate_schedule(player, events, duration)
+    Player.play(player)
+    Process.sleep(1100)
+    assert :ok = Player.pause(player)
+    Process.sleep(500)
+    assert :ok = Player.resume(player)
+    Process.sleep(1400)
+  end
+
+  test "pause & resume edge cases", %{player: player, events: events, duration: duration} do
+    Player.generate_schedule(player, events, duration)
+    assert {:error, :not_started} = Player.pause(player)
+    assert {:error, :not_paused} = Player.resume(player)
+    Player.play(player)
+    Player.pause(player)
+    assert {:error, :already_paused} = Player.pause(player)
+  end
+
+  test "event conversion", %{player: player} do
+    event1 = Event.change_program(0, 1, 40)
+    event2 = Event.note(0, 60, 1, 1000, 127)
+    events = [event1, event2]
+    duration = 100
+    assert :ok = Player.generate_schedule(player, events, duration)
+
+    change_program = MIDISynth.Command.change_program(0, 40)
+    note_on = MIDISynth.Command.note_on(0, 60, 127)
+    note_off = MIDISynth.Command.note_off(0, 60)
+
+    [command1, command2] = Player.get_schedule(player)
+    assert {1, <<^change_program::binary-size(2), ^note_on::binary-size(3)>>} = command1
+    assert {1000, ^note_off} = command2
+  end
+end