add FU-A start constraint

Author: brzep

lib/ex_webrtc/rtp/h264/nal_formats/fu.ex

@@ -70,21 +70,24 @@ defmodule ExWebRTC.RTP.H264.FU do
 
   defp do_parse(header, packet, acc)
 
-  defp do_parse(%FU.Header{start_bit: true}, packet, acc),
-    do: {:incomplete, %__MODULE__{acc | data: [packet]}}
+  defp do_parse(%FU.Header{start_bit: true}, data, %{data: []} = acc),
+    do: {:incomplete, %__MODULE__{acc | data: [data]}}
+
+  defp do_parse(%FU.Header{start_bit: true}, _data, _acc),
+    do: {:error, :last_fu_not_finished}
 
   defp do_parse(%FU.Header{start_bit: false}, _data, %__MODULE__{data: []}),
     do: {:error, :invalid_first_packet}
 
-  defp do_parse(%FU.Header{end_bit: true, type: type}, packet, %__MODULE__{data: acc_data}) do
+  defp do_parse(%FU.Header{end_bit: true, type: type}, data, %__MODULE__{data: acc_data}) do
     result =
-      [packet | acc_data]
+      [data | acc_data]
       |> Enum.reverse()
       |> Enum.join()
 
     {:ok, {result, type}}
   end
 
-  defp do_parse(_header, packet, %__MODULE__{data: acc_data} = fu),
-    do: {:incomplete, %__MODULE__{fu | data: [packet | acc_data]}}
+  defp do_parse(_header, data, %__MODULE__{data: acc_data} = fu),
+    do: {:incomplete, %__MODULE__{fu | data: [data | acc_data]}}
 end

test/ex_webrtc/rtp/h264/depayloader_test.exs

@@ -71,6 +71,26 @@ defmodule ExWebRTC.RTP.H264.DepayloaderTest do
              {bin, depayloader}
   end
 
+  test "Check starting new without ending previous FU-A" do
+    payload_fuas = <<60, 133, 128>>
+    payload_fua = <<60, 133, 129>>
+
+    depayloader = Depayloader.H264.new()
+
+    packet1 = ExRTP.Packet.new(payload_fuas, timestamp: 10)
+    packet2 = ExRTP.Packet.new(payload_fua, timestamp: 10)
+
+    {bin, depayloader} = Depayloader.H264.depayload(depayloader, packet1)
+
+    assert {nil, %{current_timestamp: 10, fu_parser_acc: %{data: [<<128>>]}}} =
+             {bin, depayloader}
+
+    {bin, depayloader} = Depayloader.H264.depayload(depayloader, packet2)
+
+    assert {nil, %{current_timestamp: nil, fu_parser_acc: nil}} =
+             {bin, depayloader}
+  end
+
   test "Check all reserved NAL types" do
     # reserved NALu types (22, 23, 30, 31)
     payloads_nalu_reserved = [<<55, 131>>, <<56, 131>>, <<62, 131>>, <<63, 131>>]