Improve the structs in the API, add docs

lib/ex_webrtc/rtp_receiver.ex

@@ -8,7 +8,11 @@ defmodule ExWebRTC.RTPReceiver do
   alias ExWebRTC.{MediaStreamTrack, Utils, RTPCodecParameters}
   alias __MODULE__.{NACKGenerator, ReportRecorder}
 
-  @type t() :: %__MODULE__{
+  @type id() :: integer()
+
+  @typedoc false
+  @type receiver() :: %{
+          id: id(),
           track: MediaStreamTrack.t(),
           codec: RTPCodecParameters.t() | nil,
           ssrc: non_neg_integer() | nil,
@@ -19,42 +23,64 @@ defmodule ExWebRTC.RTPReceiver do
           nack_generator: NACKGenerator.t()
         }
 
-  @enforce_keys [:track, :codec, :report_recorder]
-  defstruct [
-              ssrc: nil,
-              bytes_received: 0,
-              packets_received: 0,
-              markers_received: 0,
-              nack_generator: %NACKGenerator{}
-            ] ++ @enforce_keys
+  @typedoc """
+  Struct representing a receiver.
+
+  The fields mostly match these of [RTCRtpReceiver](https://developer.mozilla.org/en-US/docs/Web/API/RTCRtpReceiver),
+  except for:
+  * `id` - to uniquely identify the receiver.
+  * `codec` - codec this receiver is expected to receive.
+  """
+  @type t() :: %__MODULE__{
+          id: id(),
+          track: MediaStreamTrack.t(),
+          codec: RTPCodecParameters.t() | nil
+        }
+
+  @enforce_keys [:id, :track, :codec]
+  defstruct @enforce_keys
+
+  @doc false
+  @spec to_struct(receiver()) :: t()
+  def to_struct(receiver) do
+    receiver
+    |> Map.take([:id, :track, :codec])
+    |> then(&struct!(__MODULE__, &1))
+  end
 
   @doc false
-  @spec new(MediaStreamTrack.t(), RTPCodecParameters.t() | nil) :: t()
+  @spec new(MediaStreamTrack.t(), RTPCodecParameters.t() | nil) :: receiver()
   def new(track, codec) do
     report_recorder = %ReportRecorder{
       clock_rate: codec && codec.clock_rate
     }
 
-    %__MODULE__{
+    %{
+      id: Utils.generate_id(),
       track: track,
       codec: codec,
-      report_recorder: report_recorder
+      ssrc: nil,
+      bytes_received: 0,
+      packets_received: 0,
+      markers_received: 0,
+      report_recorder: report_recorder,
+      nack_generator: %NACKGenerator{}
     }
   end
 
   @doc false
-  @spec update(t(), RTPCodecParameters.t() | nil) :: t()
+  @spec update(receiver(), RTPCodecParameters.t() | nil) :: receiver()
   def update(receiver, codec) do
     report_recorder = %ReportRecorder{
       receiver.report_recorder
       | clock_rate: codec && codec.clock_rate
     }
 
-    %__MODULE__{receiver | codec: codec, report_recorder: report_recorder}
+    %{receiver | codec: codec, report_recorder: report_recorder}
   end
 
   @doc false
-  @spec receive_packet(t(), ExRTP.Packet.t(), non_neg_integer()) :: t()
+  @spec receive_packet(receiver(), ExRTP.Packet.t(), non_neg_integer()) :: receiver()
   def receive_packet(receiver, packet, size) do
     if packet.payload_type != receiver.codec.payload_type do
       Logger.warning("Received packet with unexpected payload_type \
@@ -65,7 +91,7 @@ defmodule ExWebRTC.RTPReceiver do
     nack_generator = NACKGenerator.record_packet(receiver.nack_generator, packet)
 
     # TODO assign ssrc when applying local/remote description.
-    %__MODULE__{
+    %{
       receiver
       | ssrc: packet.ssrc,
         bytes_received: receiver.bytes_received + size,
@@ -76,7 +102,8 @@ defmodule ExWebRTC.RTPReceiver do
     }
   end
 
-  @spec receive_rtx(t(), ExRTP.Packet.t(), non_neg_integer()) :: {:ok, ExRTP.Packet.t()} | :error
+  @spec receive_rtx(receiver(), ExRTP.Packet.t(), non_neg_integer()) ::
+          {:ok, ExRTP.Packet.t()} | :error
   def receive_rtx(receiver, rtx_packet, apt) do
     with <<seq_no::16, rest::binary>> <- rtx_packet.payload,
          ssrc when ssrc != nil <- receiver.ssrc do
@@ -94,23 +121,24 @@ defmodule ExWebRTC.RTPReceiver do
     end
   end
 
-  @spec receive_report(t(), ExRTCP.Packet.SenderReport.t()) :: t()
+  @spec receive_report(receiver(), ExRTCP.Packet.SenderReport.t()) :: receiver()
   def receive_report(receiver, report) do
     report_recorder = ReportRecorder.record_report(receiver.report_recorder, report)
 
-    %__MODULE__{receiver | report_recorder: report_recorder}
+    %{receiver | report_recorder: report_recorder}
   end
 
   @doc false
-  @spec update_sender_ssrc(t(), non_neg_integer()) :: t()
+  @spec update_sender_ssrc(receiver(), non_neg_integer()) :: receiver()
   def update_sender_ssrc(receiver, ssrc) do
     report_recorder = %ReportRecorder{receiver.report_recorder | sender_ssrc: ssrc}
     nack_generator = %NACKGenerator{receiver.nack_generator | sender_ssrc: ssrc}
-    %__MODULE__{receiver | report_recorder: report_recorder, nack_generator: nack_generator}
+
+    %{receiver | report_recorder: report_recorder, nack_generator: nack_generator}
   end
 
   @doc false
-  @spec get_stats(t(), non_neg_integer()) :: map()
+  @spec get_stats(receiver(), non_neg_integer()) :: map()
   def get_stats(receiver, timestamp) do
     %{
       id: receiver.track.id,

lib/ex_webrtc/rtp_receiver/nack_generator.ex

@@ -1,5 +1,5 @@
 defmodule ExWebRTC.RTPReceiver.NACKGenerator do
-  @moduledoc nil
+  @moduledoc false
   # for now, it mimics the Pion implementation, but there's some issues and remarks
   # 1) NACKs are send at constant interval
   # 2) no timing rules (like rtt) are taken into account
@@ -25,9 +25,6 @@ defmodule ExWebRTC.RTPReceiver.NACKGenerator do
             last_sn: nil,
             max_nack: @max_nack
 
-  @doc """
-  Records incoming RTP Packet.
-  """
   @spec record_packet(t(), ExRTP.Packet.t()) :: t()
   def record_packet(generator, packet)
 

lib/ex_webrtc/rtp_receiver/report_recorder.ex

@@ -1,5 +1,5 @@
 defmodule ExWebRTC.RTPReceiver.ReportRecorder do
-  @moduledoc nil
+  @moduledoc false
   # based on https://datatracker.ietf.org/doc/html/rfc3550#section-6.4.1
 
   import Bitwise
@@ -40,7 +40,8 @@ defmodule ExWebRTC.RTPReceiver.ReportRecorder do
             total_lost: 0
 
   @doc """
-  Records incoming RTP Packet.
+  Records incoming RTP packet.
+
   `time` parameter accepts output of `System.monotonic_time()` as a value.
   """
   @spec record_packet(t(), ExRTP.Packet.t(), integer()) :: t()
@@ -68,6 +69,7 @@ defmodule ExWebRTC.RTPReceiver.ReportRecorder do
 
   @doc """
   Records incoming RTCP Sender Report.
+
   `time` parameter accepts output of `System.monotonic_time()` as a value.
   """
   @spec record_report(t(), ExRTCP.Packet.SenderReport.t(), integer()) :: t()
@@ -79,7 +81,8 @@ defmodule ExWebRTC.RTPReceiver.ReportRecorder do
   end
 
   @doc """
-  Creates an RTCP Receiver Report.
+  Generates RTCP Receiver Report.
+
   `time` parameter accepts output of `System.monotonic_time()` as a value.
   """
   @spec get_report(t(), integer()) :: {:ok, ReceiverReport.t(), t()} | {:error, term()}

lib/ex_webrtc/rtp_sender.ex

@@ -11,7 +11,8 @@ defmodule ExWebRTC.RTPSender do
 
   @type id() :: integer()
 
-  @type t() :: %__MODULE__{
+  @typedoc false
+  @type sender() :: %{
           id: id(),
           track: MediaStreamTrack.t() | nil,
           codec: RTPCodecParameters.t() | nil,
@@ -28,21 +29,30 @@ defmodule ExWebRTC.RTPSender do
           nack_responder: NACKResponder.t()
         }
 
-  @enforce_keys [:id, :report_recorder, :nack_responder]
-  defstruct @enforce_keys ++
-              [
-                :track,
-                :codec,
-                :mid,
-                :pt,
-                :rtx_pt,
-                :ssrc,
-                :rtx_ssrc,
-                rtp_hdr_exts: %{},
-                packets_sent: 0,
-                bytes_sent: 0,
-                markers_sent: 0
-              ]
+  @typedoc """
+  Struct representing a sender.
+
+  The fields mostly match these of [RTCRtpSender](https://developer.mozilla.org/en-US/docs/Web/API/RTCRtpSender),
+  except for:
+  * `id` - to uniquely identify the sender.
+  * `codec` - codec this sender is going to send.
+  """
+  @type t() :: %__MODULE__{
+          id: id(),
+          track: MediaStreamTrack.t() | nil,
+          codec: RTPCodecParameters.t() | nil
+        }
+
+  @enforce_keys [:id, :track, :codec]
+  defstruct @enforce_keys
+
+  @doc false
+  @spec to_struct(sender()) :: t()
+  def to_struct(sender) do
+    sender
+    |> Map.take([:id, :track, :codec])
+    |> then(&struct!(__MODULE__, &1))
+  end
 
   @doc false
   @spec new(
@@ -53,15 +63,15 @@ defmodule ExWebRTC.RTPSender do
           String.t() | nil,
           non_neg_integer() | nil,
           non_neg_integer() | nil
-        ) :: t()
+        ) :: sender()
   def new(track, codec, rtx_codec, rtp_hdr_exts, mid \\ nil, ssrc, rtx_ssrc) do
     # convert to a map to be able to find extension id using extension uri
     rtp_hdr_exts = Map.new(rtp_hdr_exts, fn extmap -> {extmap.uri, extmap} end)
     # TODO: handle cases when codec == nil (no valid codecs after negotiation)
     pt = if codec != nil, do: codec.payload_type, else: nil
     rtx_pt = if rtx_codec != nil, do: rtx_codec.payload_type, else: nil
 
-    %__MODULE__{
+    %{
       id: Utils.generate_id(),
       track: track,
       codec: codec,
@@ -71,15 +81,18 @@ defmodule ExWebRTC.RTPSender do
       ssrc: ssrc,
       rtx_ssrc: rtx_ssrc,
       mid: mid,
+      packets_sent: 0,
+      bytes_sent: 0,
+      markers_sent: 0,
       report_recorder: %ReportRecorder{clock_rate: codec && codec.clock_rate},
       nack_responder: %NACKResponder{}
     }
   end
 
   @doc false
-  @spec update(t(), String.t(), RTPCodecParameters.t() | nil, RTPCodecParameters.t() | nil, [
+  @spec update(sender(), String.t(), RTPCodecParameters.t() | nil, RTPCodecParameters.t() | nil, [
           Extmap.t()
-        ]) :: t()
+        ]) :: sender()
   def update(sender, mid, codec, rtx_codec, rtp_hdr_exts) do
     if sender.mid != nil and mid != sender.mid, do: raise(ArgumentError)
     # convert to a map to be able to find extension id using extension uri
@@ -93,7 +106,7 @@ defmodule ExWebRTC.RTPSender do
       | clock_rate: codec && codec.clock_rate
     }
 
-    %__MODULE__{
+    %{
       sender
       | mid: mid,
         codec: codec,
@@ -104,11 +117,8 @@ defmodule ExWebRTC.RTPSender do
     }
   end
 
-  # Prepares packet for sending i.e.:
-  # * assigns SSRC, pt, mid
-  # * serializes to binary
   @doc false
-  @spec send_packet(t(), ExRTP.Packet.t(), boolean()) :: {binary(), t()}
+  @spec send_packet(sender(), ExRTP.Packet.t(), boolean()) :: {binary(), sender()}
   def send_packet(sender, packet, rtx?) do
     %Extmap{} = mid_extmap = Map.fetch!(sender.rtp_hdr_exts, @mid_uri)
 
@@ -146,7 +156,8 @@ defmodule ExWebRTC.RTPSender do
   end
 
   @doc false
-  @spec receive_nack(t(), ExRTCP.Packet.TransportFeedback.NACK.t()) :: {[ExRTP.Packet.t()], t()}
+  @spec receive_nack(sender(), ExRTCP.Packet.TransportFeedback.NACK.t()) ::
+          {[ExRTP.Packet.t()], sender()}
   def receive_nack(sender, nack) do
     {packets, nack_responder} = NACKResponder.get_rtx(sender.nack_responder, nack)
     sender = %{sender | nack_responder: nack_responder}
@@ -155,7 +166,7 @@ defmodule ExWebRTC.RTPSender do
   end
 
   @doc false
-  @spec get_stats(t(), non_neg_integer()) :: map()
+  @spec get_stats(sender(), non_neg_integer()) :: map()
   def get_stats(sender, timestamp) do
     %{
       timestamp: timestamp,

lib/ex_webrtc/rtp_sender/nack_responder.ex

@@ -1,5 +1,5 @@
 defmodule ExWebRTC.RTPSender.NACKResponder do
-  @moduledoc nil
+  @moduledoc false
 
   alias ExRTP.Packet
   alias ExRTCP.Packet.TransportFeedback.NACK
@@ -14,7 +14,6 @@ defmodule ExWebRTC.RTPSender.NACKResponder do
   defstruct packets: %{},
             seq_no: Enum.random(0..0xFFFF)
 
-  @doc false
   @spec record_packet(t(), Packet.t()) :: t()
   def record_packet(responder, packet) do
     key = rem(packet.sequence_number, @max_packets)
@@ -23,7 +22,6 @@ defmodule ExWebRTC.RTPSender.NACKResponder do
     %__MODULE__{responder | packets: packets}
   end
 
-  @doc false
   @spec get_rtx(t(), NACK.t()) :: {[ExRTP.Packet.t()], t()}
   def get_rtx(responder, nack) do
     seq_nos = NACK.to_sequence_numbers(nack)

lib/ex_webrtc/rtp_sender/report_recorder.ex

@@ -1,5 +1,5 @@
 defmodule ExWebRTC.RTPSender.ReportRecorder do
-  @moduledoc nil
+  @moduledoc false
 
   import Bitwise
 
@@ -30,7 +30,8 @@ defmodule ExWebRTC.RTPSender.ReportRecorder do
             octet_count: 0
 
   @doc """
-  Records outgoing RTP Packet.
+  Records incoming RTP packet.
+
   `time` parameter accepts output of `System.os_time(:native)` as a value (UNIX timestamp in :native units).
   """
   @spec record_packet(t(), ExRTP.Packet.t(), integer()) :: t()
@@ -81,9 +82,9 @@ defmodule ExWebRTC.RTPSender.ReportRecorder do
   end
 
   @doc """
-  Creates an RTCP Sender Report.
-  `time` parameter accepts output of `System.os_time(:native)` as a value (UNIX timestamp in :native units).
+  Generates a RTCP Sender Report.
 
+  `time` parameter accepts output of `System.os_time(:native)` as a value (UNIX timestamp in :native units).
   This function can be called only if at least one packet has been recorded,
   otherwise it will raise.
   """