An informal GStreamer C++ tutorial, focused on appsrc and appsink

By Oleksiy Grechnyev, IT-JIM, 2022.

https://www.it-jim.com/

This does not replace, but complements the official GStreamer tutorials. Here we focus on using appsrc and appsink for custom video (or audio) processing in the C++ code. In such situation, GStreamer is used mainly for encoding and decoding of various audio and video formats.

Note: Our examples are written in C++ and not C. We are NOT using any GLib stuff we don't really need. This includes the GLib "main loop". Our code is well-commented. For the best experience, follow the examples in the order specified below.

On Linux, the code builds fine with CMake.
On other OS-es, you'll probably have to replace pkg-config with something else.
OpenCV is used in some examples for custom image processing.

The examples:

• fun1 : An (almost) minimal GStreamer C++ example
• fun2 : Creating pipeline by hand, message processing
• capinfo : Information on pads, caps and elements, otherwise similar to fun2
• video1: Send video to appsink, display with cv::imshow()
• video2 : Decode a video file with opencv and send to a gstreamer pipeline via appsrc
• video3 : Two pipelines, with custom video processing in the middle, no audio
• audio1 : Two audio pipelines, with custom audio processing in the middle, no video
• av1 : Two pipelines, with both audio and video (video3 + audio1 combined !)