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https://gitlab.com/juergens/stabbot


https://gitlab.com/juergens/stabbot

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# stabbot



a reddit bot, that stabilizes videos



**Ranking**: https://botrank.pastimes.eu/



**Introduction**: https://www.reddit.com/r/botwatch/comments/6p1ilf/introducing_stabbot_a_bot_that_stabilizes_videos/



# User information



## how does it work?



### summoning



Mention /u/stabbot in a top-level comment to a submission.



The submission must be either:

  * a direct link to a video file

  * a html5 video

  * a link to youtube, gfycat, imgur or reddit



The video must be less than 240s



### Stabilization



**first pass**:

First it looks for edges and corners in a frame (= "image in a video").

Then it tries to find the same corners in the next frame. Then it tries

to rotate and translate the 2nd frame, so the so corresponding corners overlap with the

first frame. This transformation is saved in a separate file.

The process is repeated for all consecutive frames.



The result of the first pass is a file containing frame-to-frame transformations.



**second pass**:

Just applying the transformations would result in the video moving out of view eventually,

so the stabilized camera needs to follow the original camera. If it follows

too fast, the result will be too shaky. If it follows too slow the result will

be out of view for too long.



So the bot averages the transformation of the last 20 frames and the next 20 frames.

And this averaged transformation is then applied to frame, resulting in nice

and smooth camera movements.



### why it sometimes fails



**the black edges keep jumping around**: The could be solved by cropping the result,

but cropping too much would remove too much of the video in some cases, so

I decided against it. A positive side effect: by seeing how much the

result jumps around, you get a better feeling of how shaky the original really

was. A example of

this can be found [here](https://www.reddit.com/r/nonononoyes/comments/6vb4vb/motorcycle_takes_a_rocky_ride/dlyydcl/).



**It's way shakier then before**: The points where the frame is stabilized on, are

choosen almost randomly (actually it's dependant on the contrast, the area and some other factors). So sometimes it chooses points, that are not

part of the background, but part of the foreground. And then it switches between

stabilizing on the foreground and stabilizing on the background, resulting in

a shakier result than the original video. This happens especially if moving objekts

are a big part of the video, and if they are very well structured. A prime example of

this can be found [here](https://www.reddit.com/r/Simulated/comments/6va1j9/voxelized_explosion/dlz5zmi/).



If you are interested in ImageStabilization visit [/r/ImageStabilization](https://www.reddit.com/r/ImageStabilization/)



**it didn't reply to my summon**: There was an internal error. (e.g. video

couldn't be found, the comment was no top-level comment,

result couldn't be uploaded).



**it didn't reply to my summon on a saturday** or **the upload is takes really really long**: Many people are uploading to 

gfycat at the same time and bots have a very low priority compared to human uploaders. During peak-hours gfycat even seems to 

halt bot-uploads entirely. When that happens, all the bot can do is to try again and again, until the video finally makes a through. 

And if it doesn't work after about 2h, the video is dropped and the bot continues with the next one. 



# Dev-information



## relevant links



[guide to reddit bots](http://pythonforengineers.com/build-a-reddit-bot-part-1/)



[documention of vid.stab](https://github.com/georgmartius/vid.stab)



## testing



testing-related variables in bot.py:



    dryrun = False

    debug = False

    include_old_mentions = False



* *debug* just prints extra debug-info.

* *dryrun* won't upload videos and replies

* *include_old_mentions* will include old-summons.



I might eventually move those to env-vars.



## deployment



    git pull [email protected]:wotanii/stabbot.git

    cd stabbot

    nano secret.py

    docker-compose up --build -d

    docker-compose logs -f -t



secret.py must contain:



* imgur_id

* reddit_client_id

* reddit_client_secret

* reddit_password



### stabbot_crop



    git clone [email protected]:wotanii/stabbot.git --branch crop --single-branch stabbot_crop

    cp stabbot/secret.py stabbot_crop/

    cd stabbot_crop

    ...



## CI



if for some reason the CI-Runner stops working, you can set up a new one like this

get token from: Setting-->

CI / CD Settings --> Runners --> Specific Runners --> Setup a specific Runner manually

Configure Runner with token from above:



    docker run --rm -t -i -v /srv/gitlab-runner-stabbot/config:/etc/gitlab-runner --name gitlab-runner-stabbot gitlab/gitlab-runner register



(you may have to remove `/srv/gitlab-runner-stabbot` beforehand)



    sudo nano /srv/gitlab-runner-stabbot/config/config.toml 

    #privileged = true

    #maybe https://gitlab.com/gitlab-org/gitlab-ce/issues/64959



start runner



    docker run -d --restart always -v /srv/gitlab-runner-stabbot/config:/etc/gitlab-runner -v /var/run/docker.sock:/var/run/docker.sock  --name gitlab-runner-stabbot gitlab/gitlab-runner:latest run user=gitlab-runner working-directory=/home/gitlab-runner



view runner's logs



    docker logs gitlab-runner-stabbot