# Membrane Multimedia Framework: MPEG-TS
[](https://hex.pm/packages/membrane_mpegts_plugin)
[](https://circleci.com/gh/membraneframework/membrane_mpegts_plugin)
This package provides an element that can be used for demuxing MPEG-TS.
It is part of [Membrane Multimedia Framework](https://membraneframework.org).
## Installation
The package can be installed by adding `membrane_mpegts_plugin` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:membrane_mpegts_plugin, "~> 0.1.0"}
]
end
```
The docs can be found at [HexDocs](https://hexdocs.pm/membrane_mpegts_plugin).
## Abbreviations
PAT - Program Association Table
PMT - Program Mapping Table
## Usage
Demuxer is an element that has one `:input` and variable amount of outputs depending on the stream.
In this particular example we are demuxing a file that contains MPEG1 audio and H264 video.
```elixir
@impl true
def handle_init(path) do
children = [
source_file: %File.Source{location: path, chunk_size: 64_000},
demuxer: MPEG.TS.Demuxer,
video_parser: %H264.Parser{framerate: {24, 1}},
video_decoder: H264.Decoder,
player: SDL.Player,
audio_decoder: Mad.Decoder,
audio_converter: %SWResample.Converter{
output_caps: %Raw{channels: 2, format: :s16le, sample_rate: 48_000}
},
portaudio: PortAudio.Sink
]
links = [
link(:source_file) |> to(:demuxer),
link(:demuxer) |> via_out(Pad.ref(:output, 256)) |> to(:video_parser),
link(:demuxer) |> via_out(Pad.ref(:output, 257)) |> to(:audio_decoder),
link(:video_parser) |> to(:video_decoder),
link(:video_decoder) |> to(:player),
link(:audio_decoder) |> to(:audio_converter),
link(:audio_converter) |> to(:portaudio)
]
spec = %Spec{
children: children,
links: links,
stream_sync: :sinks
}
{{:ok, spec: spec}, %{}}
end
```
Upon successful parsing of MPEG Transport stream specific information, demuxer will notify
its parent (usally a pipeline). When the parent receives `{:mpeg_ts_stream_info, prog_map_tables}` message it will need to
link the demuxer outputs. The demuxer will continue its work when either every stream will have its
corresponding pad linked or after receiving `:pads_ready` message. If demuxer receives
`:pads_ready` it will continue its work even though some pads might not be linked.
`prog_map_tables` that is received by pipeline has following format:
```
%{
program_id => %Membrane.MPEG.TS.ProgramMapTable{
streams: %{
packet_identifier => %{
type: atom,
type_id: 0..255
}
}
}
}
```
So, far example, if we wanted to have as simple behaviour as use first stream with matching type
we would do it like this:
```elixir
@impl true
def handle_notification({:mpeg_ts_stream_info, pmt}, _from, state) do
{audio_pid, video_pid} = parse_mapping(pmt)
children = [
audio: An.Audio.Element,
video: A.Video.Element
]
links = [
link(:demuxer) |> via_out(Pad.ref(:output, audio_pid)) |> to(:audio),
link(:demuxer) |> via_out(Pad.ref(:output, video_pid)) |> to(:video)
]
spec = %Spec{
children: children,
links: links,
}
{{:ok, spec: spec}, state}
end
defp parse_mapping(mapping) do
mapping = mapping[1]
with {:ok, audio_pid} <- first_matching_stream(mapping.streams, :MPEG1_AUDIO),
{:ok, video_pid} <- first_matching_stream(mapping.streams, :H264) do
{audio_pid, video_pid}
end
end
def first_matching_stream(streams, type) do
streams
|> Enum.find(fn {_, value} -> value.type == type end)
|> case do
nil -> {:error, :no_stream}
{pid, _stream_spec} -> {:ok, pid}
end
end
```
## Copyright and License
Copyright 2019, [Software Mansion](https://swmansion.com/?utm_source=git&utm_medium=readme&utm_campaign=membrane_mpegts_plugin)
[](https://swmansion.com/?utm_source=git&utm_medium=readme&utm_campaign=membrane_mpegts_plugin)
Licensed under the [Apache License, Version 2.0](https://github.com/membraneframework/membrane_mpegts_plugin/blob/master/LICENSE)
