Add ffmpeg example (#61)

ffmpeg-examples/how-to-fix-errors.md

@@ -0,0 +1,34 @@
+# Fixes for errors
+
+To fix the following error:
+```
+Package libavdevice was not found in the pkg-config search path.
+```
+please run
+
+```
+sudo apt-get install libavdevice-dev
+```
+
+To fix the following error
+```
+Makefile:28: *** FFmpeg version should be n5.1 or above!.  Stop.
+```
+please run
+```
+sudo apt-get install software-properties-common
+sudo add-apt-repository ppa:savoury1/ffmpeg4
+sudo add-apt-repository ppa:savoury1/ffmpeg5
+sudo apt-get update
+sudo apt-get install ffmpeg --reinstall
+sudo apt-get install libavutil-dev --reinstall
+```
+
+To fix the following error:
+```
+ModuleNotFoundError: No module named 'apt_pkg'
+```
+please run:
+```
+sudo apt-get install python-apt
+```