datlt4 / gst-learn

gst-learn

Format C++ code

apt install clang-format -y
clang-format -style=microsoft -dump-config > .clang-format
sed -i 's/AlwaysBreakTemplateDeclarations: MultiLine/AlwaysBreakTemplateDeclarations: false/g' .clang-format

# To use
find . -regex '.*\.\(c\|cc\|cpp\|cxx\|cu\|h\|hh\|hpp\|hxx\|inl\|inc\|ipp\|m\|mm\)$' -exec clang-format -style=file -i {} \;

Pre-commit

python3 -m pip install pre-commit
pre-commit install      # runs every time you commit in git
pre-commit run -a       # To use
pre-commit autoupdate   # To update this file

Tutorials

Basic Tutorial 1: Hello World!

• See source code at basic-tutorial-1.cpp.

Conclusion

• Initialize GStreamer using gst_init().

• Quickly build a pipeline from a textual description using gst_parse_launch().

• Create an automatic playback pipeline using playbin.

• Signal GStreamer to start playback using gst_element_set_state().

• Sit back and relax, while GStreamer takes care of everything, using gst_element_get_bus() and gst_bus_timed_pop_filtered().

Basic tutorial 2: GStreamer concepts

• See source code at basic-tutorial-2.cpp.

Conclusion

• Create elements with gst_element_factory_make().

• Create an empty pipeline with gst_pipeline_new().

• Add elements to the pipeline with gst_bin_add_many().

• Link the elements with each other with gst_element_link().

Basic tutorial 3: Dynamic pipelines

• See source code at basic-tutorial-3.cpp.

Conclusion

• Be notified of events using GSignals.

• Connect GstPads directly instead of their parent elements.

• The various states of a GStreamer element.

Basic tutorial 4: Time management

• See source code at basic-tutorial-4.cpp.

Conclusion

• How to query the pipeline for information using GstQuery

• How to obtain common information like position and duration using gst_element_query_position() and gst_element_query_duration().

• How to seek to an arbitrary position in the stream using gst_element_seek_simple().

• In which states all these operations can be performed.

Basic tutorial 5: GUI toolkit integration

• See source code at basic-tutorial-5.cpp.

Conclusion

• How to output the video to a particular GTK Widget using the gtksink Element.

• How to refresh the GUI periodically by registering a timeout callback with g_timeout_add_seconds().

• How to convey information to the main thread by means of application messages through the bus with gst_element_post_message().

• How to be notified only of interesting messages by making the bus emit signals with gst_bus_add_signal_watch() and discriminating among all message types using the signal details.

Basic tutorial 6: Media formats and Pad Capabilities

• See source code at basic-tutorial-6.cpp.

Conclusion

• What are Pad Capabilities and Pad Template Capabilities.

• How to retrieve them with gst_pad_get_current_caps() or gst_pad_query_caps().

• That they have different meaning depending on the state of the pipeline (initially they indicate all the possible Capabilities, later they indicate the currently negotiated Caps for the Pad).

• That Pad Caps are important to know beforehand if two elements can be linked together.

• That Pad Caps can be found using the gst-inspect-1.0 tool described in Basic tutorial 10: GStreamer tools.

Basic tutorial 7: Multithreading and Pad Availability

• See source code at basic-tutorial-6.cpp.

Conclusion

• How to make parts of a pipeline run on a different thread by using queue elements.

• What is a Request Pad and how to link elements with request pads, with gst_element_request_pad_simple(), gst_pad_link() and gst_element_release_request_pad().

• How to have the same stream available in different branches by using tee elements.