Streaming Audio from Raspberry Pi to iPad Over Wi-Fi Using GStreamer

Streaming audio from a Raspberry Pi to an iPad over Wi-Fi allows for a variety of applications, from home intercom systems to real-time monitoring. Since iOS does not support receiving Bluetooth audio directly from external sources, Wi-Fi streaming is the best alternative.

In this guide, we’ll use GStreamer, a powerful multimedia framework, to capture audio from a microphone connected to the Raspberry Pi and stream it over Wi-Fi. The iPad will then receive and play the stream using an app like VLC for iOS.

Understanding the Technology

Why Not Bluetooth?

iOS does not support Bluetooth A2DP Sink mode, meaning it cannot receive audio over Bluetooth like a speaker. Instead, we leverage Wi-Fi streaming, which is more flexible and allows better control over audio quality and latency.

What is GStreamer?

GStreamer is an open-source multimedia framework that enables processing and streaming of audio and video. It provides an efficient way to capture audio, encode it, and transmit it over a network.

How Will This Work?

1. Capture audio from the microphone on the Raspberry Pi.
2. Encode the audio into a format suitable for streaming.
3. Stream it over the network using UDP or HTTP.
4. Receive the stream on the iPad using VLC or another media player.

Step 1: Install GStreamer on the Raspberry Pi

First, update the Raspberry Pi and install the necessary GStreamer packages:

sudo apt update
sudo apt install -y gstreamer1.0-tools gstreamer1.0-alsa \
    gstreamer1.0-plugins-base gstreamer1.0-plugins-good \
    gstreamer1.0-plugins-bad gstreamer1.0-plugins-ugly \
    gstreamer1.0-libav gstreamer1.0-pulseaudio

This installs:

• Core GStreamer tools (gst-launch-1.0)
• Plugins for audio capture, encoding, and streaming

Step 2: Identify Your Audio Input Device

To list all connected microphones, run:

arecord -l

You should see output like this:

**** List of CAPTURE Hardware Devices ****
card 1: USB-Audio [USB Audio], device 0: USB Audio [USB Audio]

Note the card and device numbers. If your microphone is card 1, device 0, the GStreamer device string will be plughw:1,0.

Step 3: Stream Audio Over Wi-Fi

Option 1: Low-Latency UDP Streaming (Recommended)

UDP streaming has lower latency and is ideal for real-time audio applications.

On the Raspberry Pi (Sender):

Run the following command to start streaming audio with optimized noise reduction:

gst-launch-1.0 alsasrc device=plughw:1,0 buffer-time=100000 ! \
    audioconvert ! \
    audioresample quality=10 ! \
    audio/x-raw,rate=44100,channels=1 ! \
    rtpL16pay ! \
    udpsink host=<ipad-ip> port=5004 buffer-size=65536

Replace <ipad-ip> with the actual IP address of your iPad.

On the iPad (Receiver):

1. Install VLC for iOS from the App Store.
2. Open VLC and go to Network Stream.
3. Enter:

   rtp://@:5004
   

4. Tap Play to start listening.

Option 2: HTTP MP3 Streaming (More Compatible)

MP3 streaming over HTTP introduces more latency (1-3 seconds) but is easier to access in Safari or VLC.

On the Raspberry Pi (Sender):

Run:

gst-launch-1.0 -v alsasrc device=plughw:1,0 ! audioconvert ! lamemp3enc ! \
    mpegaudioparse ! shout2send ip=<raspberry-pi-ip> port=8000 password=hackme mount=/stream.mp3

On the iPad (Receiver):

1. Open Safari or VLC for iOS.
2. Enter the following URL:

   http://<raspberry-pi-ip>:8000/stream.mp3
   

3. Press Play.

Step 4: Find Your iPad’s IP Address

Before running the streaming commands, you need to find your iPad’s IP address.

Method 1: Check in iPad Settings

1. Open Settings > Wi-Fi.
2. Tap the (i) button next to your connected Wi-Fi network.
3. Find IP Address (e.g., 192.168.1.102).

Method 2: Scan the Network from Raspberry Pi

If you want to find all devices on the network:

sudo apt install arp-scan
sudo arp-scan --localnet

Look for an entry with Apple in the manufacturer column.

Step 5: Optimize for Lower Latency

• Reduce buffering in GStreamer by setting buffer-time=100000 in the pipeline.
• Use UDP (udpsink) instead of HTTP (shout2send) for real-time streaming.
• Ensure both devices are on the same Wi-Fi network and avoid interference.

Conclusion

Using GStreamer, we successfully streamed live microphone audio from a Raspberry Pi to an iPad over Wi-Fi. This setup works for real-time intercoms, remote monitoring, or simply experimenting with audio transmission over a network.

Comparison of Methods

If low latency is important, use UDP streaming with VLC. If you need a more general-purpose solution, MP3 over HTTP is easier to access in Safari or other media players.

Happy Streaming! 🚀