# Membrane FFmpeg SWResample plugin

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Plugin performing audio conversion, resampling and channel mixing, using SWResample module of [FFmpeg](https://www.ffmpeg.org/) library.

It is a part of [Membrane Multimedia Framework](https://membrane.stream).

## Installation

Add the following line to your `deps` in `mix.exs`. Run `mix deps.get`.

```elixir
{:membrane_ffmpeg_swresample_plugin, "~> 0.18.0"}
```

The precompiled builds of the [ffmpeg](https://www.ffmpeg.org) will be pulled and linked automatically. However, should there be any problems, consider installing it manually.

### Manual instalation of dependencies

#### macOS

```shell
brew install ffmpeg
```

#### Ubuntu

```shell
sudo apt-get install ffmpeg
```

#### Arch / Manjaro

```shell
pacman -S ffmpeg
```

## Usage

The pipeline takes raw audio, converts the sample format from `s24le` to `f32le` and resamples
it to 44.1 kHz rate.

```elixir
defmodule Resampling.Pipeline do
  use Membrane.Pipeline

  alias Membrane.FFmpeg.SWResample.Converter
  alias Membrane.{File, RawAudio}

  @impl true
  def handle_init(_ctx, _opts) do
    structure = [
      child(:file_src, %File.Source{location: "/tmp/input.raw"})
      |> child(:converter, %Converter{
        input_stream_format: %RawAudio{channels: 2, sample_format: :s24le, sample_rate: 48_000},
        output_stream_format: %RawAudio{channels: 2, sample_format: :f32le, sample_rate: 44_100}
      })
      |> child(:file_sink, %File.Sink{location: "/tmp/output.raw"})
    ]

    {[spec: structure, playback: :playing], nil}
  end

  @impl true
  def handle_element_end_of_stream(:file_sink, _pad, _ctx_, _state) do
    {[playback: :stopped], nil}
  end
end
```

## Copyright and License

Copyright 2018, [Software Mansion](https://swmansion.com/?utm_source=git&utm_medium=readme&utm_campaign=membrane)

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Licensed under the [Apache License, Version 2.0](LICENSE)