gstreamer/Basic+tutorial+16+Platform-specific+elements.markdown

# Basic tutorial 16: Platform-specific elements

# Goal

Even though GStreamer is a multiplatform framework, not all the elements
are available on all platforms. For example, the audio and video sinks
depend heavily on the underlying windowing system, and a different one
needs to be selected depending on the platform. You normally do not need
to worry about this when using elements like `playbin2` or
`autovideosink`, but, for those cases when you need to use one of the
sinks that are only available on specific platforms, this tutorial hints
you some of their peculiarities.

# Linux

### `ximagesink`

A standard X-based video sink. It implements the XOverlay interface, so
the video window can be re-parented (embedded inside other windows). It
does not support scaling; it has to be performed by different means
(using the `videoscale` element, for example).

### `xvimagesink`

An X-based video sink, using the [X Video
Extension](http://en.wikipedia.org/wiki/X_video_extension) (Xv). It
implements the XOverlay interface, so the video window can be
re-parented (embedded inside other windows). It can perform scaling
efficiently, on the GPU. It is only available if the hardware and
corresponding drivers support the Xv extension.

### `cluttersink`

This is a GStreamer video sink element that sends data to a
[ClutterTexture](http://developer.gnome.org/clutter-gst/stable/ClutterGstVideoTexture.html)
which can then be used in any [Clutter](https://clutter-project.org/)
scene (See [Basic tutorial 15: Clutter
integration](Basic%2Btutorial%2B15%253A%2BClutter%2Bintegration.html)). Clutter
is a multiplatform library, so this sink is available on every platform
(as long as Clutter is installed). Clutter achieves
platform-independence by using [OpenGL](http://www.opengl.org) as the
rendering backend, so OpenGL must also be available in the system.

### `alsasink`

This audio sink outputs to the sound card via
[ALSA](http://www.alsa-project.org/) (Advanced Linux Sound
Architecture). This sink is available on almost every Linux platform. It
is often seen as a “low level” interface to the sound card, and can be
complicated to configure (See the comment on [Playback tutorial 9:
Digital audio
pass-through](Playback%2Btutorial%2B9%253A%2BDigital%2Baudio%2Bpass-through.html)).

### `pulsesink`

This sink plays audio to a [PulseAudio](http://www.pulseaudio.org/)
server. It is a higher level abstraction of the sound card than ALSA,
and is therefore easier to use and offers more advanced features. It has
been known to be unstable on some older Linux distributions, though.

# Mac OS X

### `osxvideosink`

This is the only video sink available to GStreamer on Mac OS X.

### `cluttersink`

This is a GStreamer video sink element that sends data to
a [ClutterTexture](http://developer.gnome.org/clutter-gst/stable/ClutterGstVideoTexture.html) which
can then be used in any [Clutter](https://clutter-project.org/) scene
(See [Basic tutorial 15: Clutter
integration](Basic%2Btutorial%2B15%253A%2BClutter%2Bintegration.html)). Clutter
is a multiplatform library, so this sink is available on every platform
(as long as Clutter is installed). Clutter achieves
platform-independence by using [OpenGL](http://www.opengl.org/) as the
rendering backend, so OpenGL must also be available in the system.

### `osxaudiosink`

This is the only audio sink available to GStreamer on Mac OS X.

# Windows

### `directdrawsink`

This is the oldest of the Windows video sinks, based on [Direct
Draw](http://en.wikipedia.org/wiki/DirectDraw). It requires DirectX 7,
so it is available on almost every current Windows platform. It supports
rescaling and filtering of the scaled image to alleviate aliasing.

### `dshowvideosink`

This video sink is based on [Direct
Show](http://en.wikipedia.org/wiki/Direct_Show).  It can use different
rendering back-ends, like
[EVR](http://en.wikipedia.org/wiki/Enhanced_Video_Renderer),
[VMR9](http://en.wikipedia.org/wiki/Direct_Show#Video_rendering_filters)
or
[VMR7](http://en.wikipedia.org/wiki/Direct_Show#Video_rendering_filters),
EVR only being available on Windows Vista or more recent. It supports
rescaling and filtering of the scaled image to alleviate aliasing. It
implements the XOverlay interface, so the video window can be
re-parented (embedded inside other windows).

### `d3dvideosink`

This video sink is based on
[Direct3D](http://en.wikipedia.org/wiki/Direct3D) and it’s the most
recent Windows video sink. It supports rescaling and filtering of the
scaled image to alleviate aliasing. It implements the XOverlay
interface, so the video window can be re-parented (embedded inside other
windows).

### `cluttersink`

This is a GStreamer video sink element that sends data to
a [ClutterTexture](http://developer.gnome.org/clutter-gst/stable/ClutterGstVideoTexture.html) which
can then be used in any [Clutter](https://clutter-project.org/) scene
(See [Basic tutorial 15: Clutter
integration](Basic%2Btutorial%2B15%253A%2BClutter%2Bintegration.html)). Clutter
is a multiplatform library, so this sink is available on every platform
(as long as Clutter is installed). Clutter achieves
platform-independence by using [OpenGL](http://www.opengl.org/) as the
rendering backend, so OpenGL must also be available in the system.

### `directsoundsink`

This is the default audio sink for Windows, based on [Direct
Sound](http://en.wikipedia.org/wiki/DirectSound), which is available in
all Windows versions.

### `dshowdecwrapper`

[Direct Show](http://en.wikipedia.org/wiki/Direct_Show) is a multimedia
framework similar to GStreamer. They are different enough, though, so
that their pipelines cannot be interconnected. However, through this
element, GStreamer can benefit from the decoding elements present in
Direct Show. `dshowdecwrapper` wraps multiple Direct Show decoders so
they can be embedded in a GStreamer pipeline. Use the `gst-inspect` tool
(see [Basic tutorial 10: GStreamer
tools](Basic%2Btutorial%2B10%253A%2BGStreamer%2Btools.html)) to see the
available decoders.

# Android

### `eglglessink`

This video sink is based on [OpenGL
ES](http://en.wikipedia.org/wiki/OpenGL_ES) and
[EGL](http://en.wikipedia.org/wiki/EGL_%28OpenGL%29). It supports
rescaling and filtering of the scaled image to alleviate aliasing. It
implements the XOverlay interface, so the video window can be
re-parented (embedded inside other windows).

### `openslessink`

This is the only audio sink available to GStreamer on Android. It is
based on [OpenSL
ES](http://en.wikipedia.org/wiki/OpenSL_ES).

### `androidmedia`

[android.media.MediaCodec](http://developer.android.com/reference/android/media/MediaCodec.html)
is an Android specific API to access the codecs that are available on
the device, including hardware codecs. It is available since API level
16 (JellyBean) and GStreamer can use it via the androidmedia plugin for
audio and video decoding.

# iOS

### `eglglessink`

This video sink is based on [OpenGL
ES](http://en.wikipedia.org/wiki/OpenGL_ES) and [EGL](http://en.wikipedia.org/wiki/EGL_%28OpenGL%29).
It supports rescaling and filtering of the scaled image to alleviate
aliasing. It implements the XOverlay interface, so the video window can
be re-parented (embedded inside other windows).

### `osxaudiosink`

This is the only audio sink available to GStreamer on iOS.

### `iosassetsrc`

Source element to read iOS assets, this is, documents stored in the
Library (like photos, music and videos). It can be instantiated
automatically by `playbin2` when URIs use the
`assets-library://` scheme.

### `iosavassetsrc`

Source element to read and decode iOS audiovisual assets, this is,
documents stored in the Library (like photos, music and videos). It can
be instantiated automatically by `playbin2` when URIs use the
`ipod-library://` scheme. Decoding is performed by the system, so
dedicated hardware will be used if available.

# Conclusion

This tutorial has shown a few specific details about some GStreamer
elements which are not available on all platforms. You do not have to
worry about them when using multiplatform elements like `playbin2` or
`autovideosink`, but it is good to know their personal quirks if
instancing them manually.

It has been a pleasure having you here, and see you soon\!