Hide VP8 and Opus Payloader/Depayloader modules

lib/ex_webrtc/rtp/depayloader.ex

@@ -1,57 +1,41 @@
 defmodule ExWebRTC.RTP.Depayloader do
   @moduledoc """
-  Dispatcher module and behaviour for ExWebRTC Depayloaders.
-  """
-
-  alias ExWebRTC.RTPCodecParameters
-
-  @type depayloader :: struct()
+  RTP depayloader.
 
-  @doc """
-  Creates a new depayloader struct.
+  It unpacks RTP pakcets into audio/video frames.
   """
-  @callback new(options :: any()) :: depayloader()
 
-  @doc """
-  Processes binary data from a single RTP packet, and outputs a frame if assembled.
+  alias ExWebRTC.RTPCodecParameters
 
-  Returns the frame (or `nil` if a frame could not be depayloaded yet)
-  together with the updated depayloader struct.
-  """
-  @callback depayload(depayloader(), packet :: ExRTP.Packet.t()) ::
-              {binary() | nil, depayloader()}
+  @opaque depayloader :: struct()
 
   @doc """
-  Creates a new depayloader struct that matches the passed codec parameters.
-
-  Refer to the modules implementing the behaviour for available options.
+  Creates a new depayloader that matches the passed codec parameters.
   """
-  @spec new(RTPCodecParameters.t(), any()) ::
+  @spec new(RTPCodecParameters.t()) ::
           {:ok, depayloader()} | {:error, :no_depayloader_for_codec}
-  def new(codec_params, options \\ nil) do
-    with {:ok, module} <- match_depayloader_module(codec_params.mime_type) do
-      depayloader = if is_nil(options), do: module.new(), else: module.new(options)
-
+  def new(codec_params) do
+    with {:ok, module} <- to_depayloader_module(codec_params.mime_type) do
+      depayloader = module.new()
       {:ok, depayloader}
     end
   end
 
   @doc """
-  Processes binary data from a single RTP packet using the depayloader's module,
-  and outputs a frame if assembled.
+  Processes binary data from a single RTP packet, and outputs a frame if assembled.
 
   Returns the frame (or `nil` if a frame could not be depayloaded yet)
-  together with the updated depayloader struct.
+  together with the updated depayloader.
   """
   @spec depayload(depayloader(), ExRTP.Packet.t()) :: {binary() | nil, depayloader()}
   def depayload(%module{} = depayloader, packet) do
     module.depayload(depayloader, packet)
   end
 
-  defp match_depayloader_module(mime_type) do
+  defp to_depayloader_module(mime_type) do
     case String.downcase(mime_type) do
-      "video/vp8" -> {:ok, ExWebRTC.RTP.VP8.Depayloader}
-      "audio/opus" -> {:ok, ExWebRTC.RTP.Opus.Depayloader}
+      "video/vp8" -> {:ok, ExWebRTC.RTP.Depayloader.VP8}
+      "audio/opus" -> {:ok, ExWebRTC.RTP.Depayloader.Opus}
       _other -> {:error, :no_depayloader_for_codec}
     end
   end

lib/ex_webrtc/rtp/depayloader_behaviour.ex

@@ -0,0 +1,19 @@
+defmodule ExWebRTC.RTP.Depayloader.Behaviour do
+  @moduledoc false
+
+  @type depayloader :: struct()
+
+  @doc """
+  Creates a new depayloader struct.
+  """
+  @callback new() :: depayloader()
+
+  @doc """
+  Processes binary data from a single RTP packet, and outputs a frame if assembled.
+
+  Returns the frame (or `nil` if a frame could not be depayloaded yet)
+  together with the updated depayloader struct.
+  """
+  @callback depayload(depayloader(), packet :: ExRTP.Packet.t()) ::
+              {binary() | nil, depayloader()}
+end

lib/ex_webrtc/rtp/opus/depayloader.ex

@@ -1,34 +1,23 @@
-defmodule ExWebRTC.RTP.Opus.Depayloader do
-  @moduledoc """
-  Decapsualtes Opus audio out of RTP packet.
-
-  Based on [RFC 7587: RTP Payload Format for the Opus Speech and Audio Codec](https://datatracker.ietf.org/doc/html/rfc7587).
-  """
+defmodule ExWebRTC.RTP.Depayloader.Opus do
+  @moduledoc false
+  # Decapsualtes Opus audio out of RTP packet.
+  #
+  # Based on [RFC 7587: RTP Payload Format for the Opus Speech and Audio Codec](https://datatracker.ietf.org/doc/html/rfc7587).
 
   alias ExRTP.Packet
 
-  @behaviour ExWebRTC.RTP.Depayloader
+  @behaviour ExWebRTC.RTP.Depayloader.Behaviour
 
-  @opaque t :: %__MODULE__{}
+  @type t :: %__MODULE__{}
 
   defstruct []
 
-  @doc """
-  Creates a new Opus depayloader struct.
-
-  Does not take any options/parameters.
-  """
   @impl true
-  @spec new(any()) :: t()
-  def new(_unused \\ nil) do
+  @spec new() :: t()
+  def new() do
     %__MODULE__{}
   end
 
-  @doc """
-  Takes Opus packet out of an RTP packet.
-
-  Always returns a binary as the first element.
-  """
   @impl true
   @spec depayload(t(), Packet.t()) :: {binary(), t()}
   def depayload(%__MODULE__{} = depayloader, %Packet{payload: payload}),

lib/ex_webrtc/rtp/opus/payloader.ex

@@ -1,33 +1,20 @@
-defmodule ExWebRTC.RTP.Opus.Payloader do
-  @moduledoc """
-  Encapsulates Opus audio packet into an RTP packet.
+defmodule ExWebRTC.RTP.Payloader.Opus do
+  @moduledoc false
+  # Encapsulates Opus audio packet into an RTP packet.
+  #
+  # Based on [RFC 7587: RTP Payload Format for the Opus Speech and Audio Codec](https://datatracker.ietf.org/doc/html/rfc7587).
 
-  Based on [RFC 7587: RTP Payload Format for the Opus Speech and Audio Codec](https://datatracker.ietf.org/doc/html/rfc7587).
-  """
+  @behaviour ExWebRTC.RTP.Payloader.Behaviour
 
-  @behaviour ExWebRTC.RTP.Payloader
-
-  @opaque t :: %__MODULE__{}
+  @type t :: %__MODULE__{}
 
   defstruct []
 
-  @doc """
-  Creates a new Opus payloader struct.
-
-  Does not take any options/parameters.
-  """
   @impl true
-  @spec new(any()) :: t()
-  def new(_unused \\ nil) do
+  def new(_max_payload_size) do
     %__MODULE__{}
   end
 
-  @doc """
-  Packs Opus packet into an RTP packet.
-
-  Fields from RTP header like ssrc, timestamp etc. are set to 0.
-  Always returns a single RTP packet.
-  """
   @impl true
   @spec payload(t(), binary()) :: {[ExRTP.Packet.t()], t()}
   def payload(%__MODULE__{} = payloader, packet) when packet != <<>> do

lib/ex_webrtc/rtp/payloader.ex

@@ -1,53 +1,43 @@
 defmodule ExWebRTC.RTP.Payloader do
   @moduledoc """
-  Dispatcher module and behaviour for ExWebRTC Payloaders.
-  """
-
-  alias ExWebRTC.RTPCodecParameters
+  RTP payloader.
 
-  @type payloader :: struct()
-
-  @doc """
-  Creates a new payloader struct.
+  It packs audio/video frames into one or more RTP packets.
   """
-  @callback new(options :: any()) :: payloader()
 
-  @doc """
-  Packs a frame into one or more RTP packets.
+  alias ExWebRTC.RTPCodecParameters
 
-  Returns the packets together with the updated payloader struct.
-  """
-  @callback payload(payloader(), frame :: binary()) :: {[ExRTP.Packet.t()], payloader()}
+  @opaque payloader :: struct()
 
   @doc """
-  Creates a new payloader struct that matches the passed codec parameters.
+  Creates a new payloader that matches the passed codec parameters.
 
-  Refer to the modules implementing the behaviour for available options.
+  * max_payload_size - determines the maximum size of a single RTP packet outputted by the payloader.
+  It must be greater than `100`, and is set to `1000` by default.
   """
-  @spec new(RTPCodecParameters.t(), any()) ::
+  @spec new(RTPCodecParameters.t(), integer()) ::
           {:ok, payloader()} | {:error, :no_payloader_for_codec}
-  def new(codec_params, options \\ nil) do
-    with {:ok, module} <- match_payloader_module(codec_params.mime_type) do
-      payloader = if is_nil(options), do: module.new(), else: module.new(options)
-
+  def new(codec_params, max_payload_size \\ 1000) do
+    with {:ok, module} <- to_payloader_module(codec_params.mime_type) do
+      payloader = module.new(max_payload_size)
       {:ok, payloader}
     end
   end
 
   @doc """
-  Packs a frame into one or more RTP packets using the payloader's module.
+  Packs a frame into one or more RTP packets.
 
-  Returns the packets together with the updated payloader struct.
+  Returns the packets together with the updated payloader.
   """
   @spec payload(payloader(), binary()) :: {[ExRTP.Packet.t()], payloader()}
   def payload(%module{} = payloader, frame) do
     module.payload(payloader, frame)
   end
 
-  defp match_payloader_module(mime_type) do
+  defp to_payloader_module(mime_type) do
     case String.downcase(mime_type) do
-      "video/vp8" -> {:ok, ExWebRTC.RTP.VP8.Payloader}
-      "audio/opus" -> {:ok, ExWebRTC.RTP.Opus.Payloader}
+      "video/vp8" -> {:ok, ExWebRTC.RTP.Payloader.VP8}
+      "audio/opus" -> {:ok, ExWebRTC.RTP.Payloader.Opus}
       _other -> {:error, :no_payloader_for_codec}
     end
   end

lib/ex_webrtc/rtp/payloader_behaviour.ex

@@ -0,0 +1,17 @@
+defmodule ExWebRTC.RTP.Payloader.Behaviour do
+  @moduledoc false
+
+  @type payloader :: struct()
+
+  @doc """
+  Creates a new payloader struct.
+  """
+  @callback new(max_payload_size :: integer()) :: payloader()
+
+  @doc """
+  Packs a frame into one or more RTP packets.
+
+  Returns the packets together with the updated payloader struct.
+  """
+  @callback payload(payloader(), frame :: binary()) :: {[ExRTP.Packet.t()], payloader()}
+end

lib/ex_webrtc/rtp/vp8/depayloader.ex

@@ -1,50 +1,36 @@
-defmodule ExWebRTC.RTP.VP8.Depayloader do
-  @moduledoc """
-  Reassembles VP8 frames from RTP packets.
+defmodule ExWebRTC.RTP.Depayloader.VP8 do
+  @moduledoc false
+  # Reassembles VP8 frames from RTP packets.
+  #
+  # Based on [RFC 7741: RTP Payload Format for VP8 Video](https://datatracker.ietf.org/doc/html/rfc7741).
 
-  Based on [RFC 7741: RTP Payload Format for VP8 Video](https://datatracker.ietf.org/doc/html/rfc7741).
-  """
-
-  @behaviour ExWebRTC.RTP.Depayloader
+  @behaviour ExWebRTC.RTP.Depayloader.Behaviour
 
   require Logger
 
   alias ExWebRTC.RTP.VP8.Payload
 
-  @opaque t() :: %__MODULE__{
-            current_frame: nil,
-            current_timestamp: nil
-          }
+  @type t() :: %__MODULE__{
+          current_frame: nil,
+          current_timestamp: nil
+        }
 
   defstruct [:current_frame, :current_timestamp]
 
-  @doc """
-  Creates a new VP8 depayloader struct.
-
-  Does not take any options/parameters.
-  """
   @impl true
-  @spec new(any()) :: t()
-  def new(_unused \\ nil) do
+  def new() do
     %__MODULE__{}
   end
 
-  @doc """
-  Reassembles VP8 frames from subsequent RTP packets.
-
-  Returns the frame (or `nil` if a frame could not be depayloaded yet)
-  together with the updated depayloader struct.
-  """
   @impl true
-  @spec depayload(t(), ExRTP.Packet.t()) :: {binary() | nil, t()}
   def depayload(depayloader, packet)
 
   def depayload(depayloader, %ExRTP.Packet{payload: <<>>, padding: true}), do: {nil, depayloader}
 
   def depayload(depayloader, packet) do
     case Payload.parse(packet.payload) do
       {:ok, vp8_payload} ->
-        do_write(depayloader, packet, vp8_payload)
+        do_depayload(depayloader, packet, vp8_payload)
 
       {:error, reason} ->
         Logger.warning("""
@@ -56,7 +42,7 @@ defmodule ExWebRTC.RTP.VP8.Depayloader do
     end
   end
 
-  defp do_write(depayloader, packet, vp8_payload) do
+  defp do_depayload(depayloader, packet, vp8_payload) do
     depayloader =
       case {depayloader.current_frame, vp8_payload} do
         {nil, %Payload{s: 1, pid: 0}} ->

lib/ex_webrtc/rtp/vp8/payload.ex

@@ -1,9 +1,8 @@
 defmodule ExWebRTC.RTP.VP8.Payload do
-  @moduledoc """
-  Defines VP8 payload structure stored in RTP packet payload.
-
-  Based on [RFC 7741: RTP Payload Format for VP8 Video](https://datatracker.ietf.org/doc/html/rfc7741).
-  """
+  @moduledoc false
+  # Defines VP8 payload structure stored in RTP packet payload.
+  #
+  # Based on [RFC 7741: RTP Payload Format for VP8 Video](https://datatracker.ietf.org/doc/html/rfc7741).
 
   @type t() :: %__MODULE__{
           n: 0 | 1,