# Set up the source stream using GStreamer

Use GStreamer, a command-line tool to configure your source stream.

We recommend using GStreamer v1.18 or later.

## Example

```
gst-launch-1.0 -v

videotestsrc ! video/x-raw,width=1920,height=1080,framerate=30/1 !

x264enc tune=zerolatency bitrate=500 speed-preset=superfast key-int-max=60 !

h264parse ! queue ! mux.

audiotestsrc ! audio/x-raw,rate=44100 !

voaacenc bitrate=128000 ! queue ! mux.

flvmux streamable=true name=mux !

rtmpsink location="rtmp://<rtmp-server-ip-or-url>/<path>"
```

## Command breakdown

The table describes each part of the command:

### Video component

| Command | Description |
| :-- | :-- |
| `videotestsrc` | This is a test video source in GStreamer, which generates a test pattern. Replace this with your actual video source (e.g. v4l2src for webcams). |
| `video/x-raw,width=1920,height=1080,framerate=30/1` | This caps filter sets the resolution and framerate of the raw video ( **1920x1080 sets the resolution to 1080p**). |
| `x264enc` | Encodes the video as H.264. `tune=zerolatency` lowers latency. `bitrate=500` sets the bitrate to 500 kbps. `speed-preset=superfast` selects the encoding-speed preset. `key-int-max=60` sets a 60-frame keyframe interval, which is two seconds at 30 frames per second. Match this value to the **Input key frame interval** configured in [MK.IO](https://docs.mediakind.com/mkio/how-to/live-streaming/set-up-a-live-streaming-event#configure-a-live-event). `h264parse` prepares the H.264 stream for RTMP. |

### Audio component

| Command | Description |
| :-- | :-- |
| `audiotestsrc` | A test audio source for generating sample audio. Replace with your own audio source. |
| `voaacenc` | Encodes the audio to AAC, which is compatible with RTMP. |
| `queue` | Adds buffers between streams to help with sync issues. |

### RTMP component

| Command | Description |
| :-- | :-- |
| `flvmux` | Packs the H.264 video (and audio if included) into an FLV container, suitable for RTMP. |
| `rtmpsink` | Sends the output stream to an RTMP server. |
| `location="rtmp://<rtmp-server-ip-or-url>/<path>"` | The RTMP **Input URL** provided after you [start the live event](https://docs.mediakind.com/mkio/how-to/live-streaming/set-up-a-live-streaming-event#start-streaming). |