# Membrane Opus plugin
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Opus encoder and decoder.
It is a part of [Membrane Multimedia Framework](https://membrane.stream).
## Installation
The package can be installed by adding `membrane_opus_plugin` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:membrane_opus_plugin, "~> 0.20.3"}
]
end
```
This package depends on [libopus](http://opus-codec.org/docs/) library. The precompiled builds will be pulled and linked automatically. However, should there be any problems, consider installing it manually.
### Manual instalation of dependencies
#### Ubuntu
```
sudo apt-get install libopus-dev
```
#### Arch/Manjaro
```
pacman -S opus
```
#### MacOS
```
brew install opus
```
#### MacOS M1/M2 (Apple silicon)
On Apple M1/M2 chips, one needs to export variables:
```
export C_INCLUDE_PATH=$C_INCLUDE_PATH:$(brew --cellar)/opus/1.3.1/include
export LIBRARY_PATH=$LIBRARY_PATH:$(brew --cellar)/opus/1.3.1/lib
```
On different local setups, directory and version names may differ.
## Usage
### Encoder
The pipeline encodes a sample raw file and saves it as an opus file:
```elixir
defmodule Membrane.ReleaseTest.Pipeline do
use Membrane.Pipeline
alias Membrane.RawAudio
@input_filename "/tmp/input.raw"
@output_filename "/tmp/output.opus"
@impl true
def handle_init(_ctx, _options) do
structure =
child(:source, %Membrane.File.Source{
location: @input_filename
})
|> child(:encoder, %Membrane.Opus.Encoder{
application: :audio,
input_stream_format: %RawAudio{
channels: 2,
sample_format: :s16le,
sample_rate: 48_000
}
})
|> child(:parser, %Membrane.Opus.Parser{delimitation: :delimit})
|> child(:sink, %Membrane.File.Sink{
location: @output_filename
})
{[spec: structure], %{}}
end
end
```
Opus audio generally needs to be packaged in an [Ogg container](https://xiph.org/ogg/) in order to be played by a
media player. See `Membrane.Ogg.Payloader` in the [Membrane Ogg Plugin](https://github.com/membraneframework/membrane_ogg_plugin).
### Decoder
The pipeline parses, decodes a sample opus file and then saves it as a raw file:
```elixir
defmodule Membrane.ReleaseTest.Pipeline2 do
use Membrane.Pipeline
@input_filename "/tmp/input.raw"
@output_filename "/tmp/output.opus"
@impl true
def handle_init(_ctx, _options) do
structure =
child(:source, %Membrane.File.Source{
location: @input_filename
})
|> child(:parser, Membrane.Opus.Parser)
|> child(:opus, Membrane.Opus.Decoder)
|> child(:sink, %Membrane.File.Sink{
location: @output_filename
})
{[spec: structure], %{}}
end
end
```
## Copyright and License
Copyright 2019, [Software Mansion](https://swmansion.com/?utm_source=git&utm_medium=readme&utm_campaign=membrane_opus_plugin)
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Licensed under the [Apache License, Version 2.0](LICENSE)