GSoC ’17 Wrap Up – GNU MediaGoblin

Prologue

Aaand, my open source journey continues! I was very fortunate to get selected for Google Summer of Code (GSoC) this year. I have to admit that it has propelled me to work with many open source tools.

I worked on extending the video player in GNU MediaGoblin to accommodate multiple resolutions of the video. It has been a great experience for me! I am extremely grateful to my mentors, Boris Bobrov and Christopher Webber.

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What I have worked on so far…

Community Bonding Period

May 4, 2017 – May 29, 2017

As I was quite new to the technologies that were required for this project, I spent most of my time getting used to Celery, Gstreamer and VideoJS.

• I built a sample project to get used to scheduling jobs and prioritizing them using Celery. It was really helpful for designing and implementing parallelism in transcoding video into multiple resolutions.
• I looked at some of the VideoJS plugins for rendering multiple qualities of video.
• We finalized the design changes for the backend.

Phase 1

May 30, 2017 – June 26, 2017

The main design change is adding the workflow method to the Class VideoProcessingManager. The Celery tasks are of two types: main_task and complimentary_task. The video is transcoded to the default resolution (which is set by the instance owner) in the main_task. After completion of the main_task, the video is transcoded to the other resolutions in different complimentary_tasks concurrently.

Major commits

• 16ef1164      Modify CommonVideoProcessor to accommodate multiple qualities
• 7cc9b6d1      Add main_task, complimentary_task and cleanup
• 9a27fa60      Add additional celery config settings
  
• 25ecdec9      Add priority to the celery tasks
• 2771f467      Add VideoProcessingManager.workflow() tests
• ee2b53de     Add test_chord for TestSubmissionVideo

Commits Link: https://gitlab.com/vijeth-aradhya/mediagoblin/commits/multiple-qualities-backend

Phase 2

June 27, 2017 – July 24, 2017

The major changes committed during this period are upgrading the VideoJS player version to v5.20.1 and adding video-resolution-switcher (v0.4.2), a VideoJS plugin. At this point, the video player could change the resolution of the video.

Major commits

• 809ebf45     Add get_all_media() in MediaEntryMixin
• ca469bb0     Add video-resolution-switcher (video.js plugin) v0.4.2
• d66d08d1    Change video.js version to v5.20.1
• b57a682c     Add change-video-resolution.js to start video-resolution-switcher plugin
• 9dea49e6     Modify video.html to add video-resolution-switcher plugin

Commits Link: https://gitlab.com/vijeth-aradhya/mediagoblin/commits/multiple-qualities-frontend

Final Phase

July 25, 2017 – August 29, 2017

In this phase, I concentrated on perfecting the work that I had done. I fixed small bugs, modified the logging and added more tests. I also modified the processing panel to show the progress of processing the video to the default resolution (previously, only the total progress of video processing was shown). Hence, I had to do a migration to the MediaEntry table for this to be possible.

Major commits

• 36c1e7dc     Replace print statements to logging
• 3456abe9     Fix percentage reporting
• 170cd28f      Create a seperate test for get_all_media
• beb9121c     Add main_transcoding_progress column migration
• b89e12a2     Add main_transcoding_progress to ProgressCallback
• e86e08ae     Show default resolution progress in processing panel

Commits Link: https://gitlab.com/vijeth-aradhya/mediagoblin/commits/transcoding_progress

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Further work that can be done…

I feel that I have successfully completed the proposed project, but there is always scope for improvement. I have decided to stick around with the MediaGoblin community even after GSoC so that I can continue to improve the video plugin, contribute to other parts of the code and help newcomers to start contributing in the future.

More features/ideas

• One of the features that is required is to show the real time progress of processing of each of the resolutions. Currently, only the total progress and the default resolution progress is shown in the processing panel.
• I think that there should be better error handling after we shifted to workflow() from ProcessMedia.run(). Currently, we directly schedule the Celery tasks by calling workflow() in submit/lib.py but we previously scheduled them by calling ProcessMedia.run() in processing/task.py.
• When the user has low network connection and he/she is trying to watch a video, then the player has to automatically switch to a lower resolution of the video (adaptive streaming discussion). MPEG DASH support might seem a bit too far-fetched right now, but it is still a good addition to the player.

Outstanding bugs

If there are any bugs/issues, then they will be listed in the issue tracker.

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