website/content/blog/gstreamer.md

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---
title: "GStreamer"
date: 2020-02-08T20:46:36-05:00
draft: false
tags: [ "Audio-Video" ]
medium_enabled: true
---
GStreamer is a pipeline based multimedia framework that goes from capture, processing, to a sink such as a X window or UDP sink.
To install on Ubuntu run,
```bash
sudo apt install gstreamer1.0-tools
```
Pipelines are indicated via `!`.
To capture your webcam feed and display it in a X window, run the following:
```bash
gst-launch-1.0 v4l2src device=/dev/video0 ! videoconvert ! ximagesink
```
For the PiCar project I'm on, I need to send the video from the raspberry pi over the network as fast as possible. The next couple commands have options that reflect this.
On the PiCar, I send h264 video over the network. You might need to install an additional package for h264 encoding to work.
```bash
sudo apt install gstreamer1.0-plugins-ugly
```
To send h264 video over the network,
```bash
gst-launch-1.0 \
v4l2src device=/dev/video0 ! \
videoconvert ! \
x264enc ! \
rtph264pay ! \
udpsink host=192.168.0.2 port=5000
```
To send it as fast as you can,
```bash
gst-launch-1.0 \
v4l2src device=/dev/video0 ! \
videoconvert ! \
x264enc interlaced=true tune=zerolatency speed-preset=ultrafast ! \
rtph264pay ! \
udpsink host=192.168.0.2 port=5000
```
To send it as fast as possible under a given framerate (ex: 30)
```bash
gst-launch-1.0 \
v4l2src device=/dev/video0 ! \
videoconvert ! \
videorate ! \
video/x-raw,framerate=30/1 ! \
x264enc interlaced=true tune=zerolatency speed-preset=ultrafast ! \
rtph264pay ! \
udpsink host=192.168.0.2 port=5000
```
To receive it and display it on an X-window,
```bash
gst-launch-1.0 \
udpsrc port=5000 ! \
application/x-rtp,payload=96 ! \
rtph264depay ! \
decodebin ! \
videoconvert n-threads=4 ! \
ximagesink
```