chrismugisha/gst-airplay

GStreamer source element for AirPlay video streams

A GStreamer plugin that provides an airplaysrc element for receiving video streamed from Apple devices using the AirPlay protocol. Audio is currently not supported.

Here's a screenshot showing the iPad screen in OBS Studio:

Installation

See below for build instructions. Once you have the file libgstairplay.so, you must let GStreamer find it. You can do one of the following:

• place the libgstairplay.so file in ~/.local/share/gstreamer-1.0/plugins (create this plugins directory if it doesn't exist already), or
• use the --gst-plugin-path option with gst-launch (for example gst-launch-1.0 --gst-plugin-path=~/my-gst-plugins airplaysrc ! ..., see below for examples of complete pipelines), or
• add the directory containing the plugin to the GST_PLUGIN_PATH environment variable.

Usage

The airplaysrc element can be used like other video sources in GStreamer pipelines. Examples are shown below.

Typical use will require the following packages (tested on Ubuntu 20.04):

gstreamer1.0-tools
gstreamer1.0-plugins-good
gstreamer1.0-plugins-bad
gstreamer1.0-libav
libavahi-compat-libdnssd1
libplist3

To stream the video from an iPad, once you have a GStreamer pipeline running, select "Screen Mirroring" in the iPad control center. You should see "gstairplay" as a mirroring destination. Select it, and the streaming should start after a few seconds.

Showing the video in a window

The gst-launch tool can be used to run a pipeline that shows the video stream in a new window:

gst-launch-1.0 airplaysrc ! queue ! h264parse ! avdec_h264 max-threads=1 ! autovideosink

Explanation: the video stream is received in the H.264 format. The stream must be parsed (h264parse) and decoded (avdec_h264) before showing in a window (autovideosink). The queue element adds some buffering. The max-threads=1 decoding option can help reduce latency.

Using as a source in OBS Studio

The airplaysrc element can be used with the OBS GStreamer plugin to configure an OBS source that shows the AirPlay video stream:

1. Install the OBS Gstreamer plugin. After compiling, I put the file obs-gstreamer.so in the directory ~/.config/obs-studio/plugins/obs-gstreamer/bin/64bit/.

2. In your OBS scene, add a "GStreamer Source"

3. Set the pipeline parameter, using airplaysrc as first element. I use the following:

   airplaysrc ! queue ! h264parse ! avdec_h264 max-threads=1 ! videoconvert ! videoscale ! video.
   

4. For best results, set the canvas and output sizes to the resolution of the AirPlay stream.

Using as a Linux camera device

Using the v4l2loopback kernel module, you can expose the AirPlay video stream as a camera device in Linux.

1. Install the v4l2loopback module. Your distribution might have it as a package, for example v4l2loopback-dkms in Ubuntu 20.04.

2. Load the module with appropriate options. I use the following:

   sudo modprobe v4l2loopback devices=1 video_nr=10 card_label="AirPlay Cam" exclusive_caps=1 max_buffers=3
   

   This creates a virtual camera with name "AirPlay Cam" and device /dev/video10.

3. Start a GStreamer pipeline that feeds the AirPlay stream to the video device:

   gst-launch-1.0 -v airplaysrc ! queue ! h264parse ! avdec_h264 max-threads=1 ! videoconvert ! videoscale ! v4l2sink device=/dev/video10
   

Once you start streaming from the Apple device, you should see "AirPlay Cam" in the list of cameras on your computer.

Troubleshooting

Call gst-inspect-1.0 libgstairplay.so (giving the path where the libgstairplay.so file is located) to check for problems such as missing libraries. For example if it says libplist.so.3: cannot open shared object file: No such file or directory, you can fix it by installing the libplist3 package (on Ubuntu 20.04 at least).

If you get an uninformative error message such as Could not load plugin file: File "libgstairplay.so" appears to be a GStreamer plugin, but it failed to initialize, try running again with GST_DEBUG=4 gst-inspect-1.0 build/libgstairplay.so.

Building

First install the build dependencies. The following packages are needed on Ubuntu 20.04:

git
gcc
pkg-config
cmake
gstreamer1.0-tools
libgstreamer1.0-dev
libgstreamer-plugins-base1.0-dev
libavahi-compat-libdnssd-dev
libplist-dev
libssl-dev
meson
ninja-build

Then clone and build this project. I use the following:

git clone https://github.com/knuesel/gst-airplay
cd gst-airplay
meson build
ninja -C build

You should now have the compiled plugin libgstairplay.so in the build directory. To check that it is a valid GStreamer plugin, run:

gst-inspect-1.0 build/libgstairplay.so 

This should display something such as

Plugin Details:
  Name                     airplay
  Description              receive video through Apple AirPlay
  Filename                 build/libgstairplay.so
  Version                  0.1
  License                  GPL
  Source module            gst-airplay-plugin
  Binary package           GStreamer airplay Plug-ins
  Origin URL               https://github.com/knuesel/gst-airplay

  airplaysrc: AirPlay source

  1 features:
  +-- 1 elements

If you get an error message, see the Troubleshooting section.

If you have a valid plugin, you can proceed to install it (see the Installation section at the top of this page).

Credits

The pluging code is based on gst-template and uses the AirPlay implementation from RPiPlay with some changes (published in this fork).

License

The plugin makes use of RPiPlay so it is licensed under the GNU GPL 3.0.