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mpeg_ts

2.0.1
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MPEG Transport Stream (TS) library.

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mpeg_ts lib mpeg ts pat.ex
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lib/mpeg/ts/pat.ex 

defmodule MPEG.TS.PAT do

  alias MPEG.TS.PSI



  @moduledoc """

  Program Association Table.

  """



  @type program_id_t :: 0..65_535

  @type program_pid_t :: 0..8191

  @type t :: %{required(program_id_t()) => program_pid_t()}



  @entry_length 4



  def unmarshal(data, is_start_unit) do

    with {:ok, %PSI{table: table}} <- PSI.unmarshal(data, is_start_unit),

         {:ok, table} <- unmarshal_table(table) do

      {:ok, table}

    end

  end



  # Unmarshals Program Association Table data. Each entry should be 4 bytes

  # long. If provided data length is not divisible by entry length an error

  # shall be returned.

  @spec unmarshal_table(binary) :: {:ok, t()} | {:error, :invalid_data}

  def unmarshal_table(data) when rem(byte_size(data), @entry_length) == 0 do

    programs =

      for <<program_number::16, _reserved::3, pid::13 <- data>>,

        into: %{} do

        {program_number, pid}

      end



    {:ok, programs}

  end



  def unmarshal_table(_) do

    {:error, :invalid_data}

  end

end