Merge pull request #2 from membraneframework-labs/handle_alignment_in…

…dicator

Add handling of `alignment_indicator`

lib/mpeg/ts/packet.ex

@@ -67,16 +67,17 @@ defmodule MPEG.TS.Packet do
          pusi = parse_flag(payload_unit_start_indicator),
          scrambling = parse_scrambling_control(transport_scrambling_control),
          {:ok, adaptation, data} <- parse_payload(optional_fields, adaptation_field_id, pid_class) do
-      packet = %__MODULE__{
-        pusi: pusi,
-        pid: pid,
-        payload: data,
-        scrambling: scrambling,
-        continuity_counter: continuity_counter,
-        discontinuity_indicator: Map.get(adaptation, :discontinuity_indicator, false),
-        random_access_indicator: Map.get(adaptation, :random_access_indicator, false),
-        pcr: Map.get(adaptation, :pcr, nil)
-      }
+      packet =
+        %__MODULE__{
+          pusi: pusi,
+          pid: pid,
+          payload: data,
+          scrambling: scrambling,
+          continuity_counter: continuity_counter,
+          discontinuity_indicator: Map.get(adaptation, :discontinuity_indicator, false),
+          random_access_indicator: Map.get(adaptation, :random_access_indicator, false),
+          pcr: Map.get(adaptation, :pcr, nil)
+        }
 
       {:ok, packet}
     else

lib/mpeg/ts/partial_pes.ex

@@ -12,9 +12,10 @@ defmodule MPEG.TS.PartialPES do
           data: binary(),
           stream_id: pos_integer(),
           pts: pos_integer(),
-          dts: pos_integer()
+          dts: pos_integer(),
+          is_aligned: boolean()
         }
-  defstruct [:data, :stream_id, :pts, :dts]
+  defstruct [:data, :stream_id, :pts, :dts, :is_aligned]
 
   require Logger
 
@@ -36,13 +37,15 @@ defmodule MPEG.TS.PartialPES do
     # Packet length is ignored as the field is also allowed to be zero in case
     # the payload is a video elementary stream. If the PES packet length is set
     # to zero, the PES packet can be of any length.
+
     with {:ok, optional, payload} <- parse_optional(optional_fields, has_header?(stream_id)) do
       {:ok,
        %__MODULE__{
          data: payload,
          stream_id: stream_id,
          dts: Map.get(optional, :dts),
-         pts: Map.get(optional, :pts)
+         pts: Map.get(optional, :pts),
+         is_aligned: Map.get(optional, :is_aligned, false)
        }}
     end
   end
@@ -64,7 +67,7 @@ defmodule MPEG.TS.PartialPES do
            0b10::2,
            _scrambling_control::2,
            _priority::1,
-           _data_alignment_indicator::1,
+           data_alignment_indicator::1,
            _copyright::1,
            _original_or_copy::1,
            pts_dts_indicator::2,
@@ -82,15 +85,34 @@ defmodule MPEG.TS.PartialPES do
        ) do
     pts_dts_indicator = parse_pts_dts_indicator(pts_dts_indicator)
 
-    with {:ok, pts_dts, _rest} <- parse_pts_dts_field(optional_fields, pts_dts_indicator) do
-      {:ok, pts_dts, rest}
+    with {:ok, optionals_map, _rest} <- parse_pts_dts_field(optional_fields, pts_dts_indicator),
+         {:ok, optionals_map} =
+           parse_data_alignment_indicator(data_alignment_indicator, optionals_map) do
+      {:ok, optionals_map, rest}
     end
   end
 
   defp parse_optional(_data, _has_header) do
     {:error, :invalid_optional_field}
   end
 
+  defp parse_data_alignment_indicator(alignment_indicator, optionals_map) do
+    alignment_indicator_flag =
+      case alignment_indicator do
+        0b0 -> false
+        0b1 -> true
+      end
+
+    optionals_map =
+      Map.put(
+        optionals_map,
+        :is_aligned,
+        alignment_indicator_flag
+      )
+
+    {:ok, optionals_map}
+  end
+
   defp parse_pts_dts_indicator(0b11), do: :pts_and_dts
   defp parse_pts_dts_indicator(0b01), do: :forbidden
   defp parse_pts_dts_indicator(0b10), do: :only_pts

lib/mpeg/ts/pes.ex

@@ -1,4 +1,4 @@
 defmodule MPEG.TS.PES do
-  @derive {Inspect, only: [:stream_id, :pts, :dts]}
-  defstruct [:data, :stream_id, :pts, :dts]
+  @derive {Inspect, only: [:stream_id, :pts, :dts, :is_aligned]}
+  defstruct [:data, :stream_id, :pts, :dts, :is_aligned]
 end

lib/mpeg/ts/stream_queue.ex

@@ -102,7 +102,9 @@ defmodule MPEG.TS.StreamQueue do
         data: data,
         stream_id: leader.stream_id,
         pts: leader.pts,
-        dts: leader.dts
+        dts: leader.dts,
+        # the information about alignment should be available in the first `PartialPES`
+        is_aligned: leader.is_aligned
       }
     else
       nil