4/10/20

Extracting video from blob url

First press F12, then select Network tab. reload page, then play video.  You should see a file called playlist.m3u8.  Right click it then copy address.

On a command line(Win, Mac, Linux), type youtube-dl followed by pasting the m3u8 link, then enter.

Of course you should already have youtube-dl installed.

4/9/20

Disable ubuntu update manager, timer from command line


On command lines:
sudo systemctl disable apt-daily.timer
sudo systemctl disable apt-daily-upgrade.timer
then edit 2 files:
sudo vi /etc/apt/apt.conf.d/10periodic
sudo vi /etc/apt/apt.conf.d/20auto-upgrades
In both files, change "1" to "0".

4/4/20

Creating Time Lapsed video from dashcam videos

Time lapsed video are usually create from photos.  Here's how to create one from dashcam videos.
First move all videos into a single folder, then list files and redirect output into a text file.  On linux, it's `ls > files.txt`, on Windows, it's `dir /B > files.txt`.

Then edit this file.  This file should list videos in the order of timestamp, if not, adjust them manually. Remove any files that's not video or any videos that you don't want to be included in the final video.  Put 'file ' at the beginning of every line.  (In Vim, you can do this by :%s/^/file /g)

Then create a raw video by select one frame in every 30 frames from all the videos in the file:

ffmpeg -f concat -i files.txt -vf "select=not(mod(n\,30)),setpts=N/(FRAME_RATE*TB)" -vcodec rawvideo -pix_fmt yuv420p -an raw.yuv
Because this is uncompressed raw video, its size will be huge, probably tens of GigBytes. You probably don't want to play it on your computer, let alone uploaded to youtube.  To make it playable, we need to compress it to mp4 format:

ffmpeg -f rawvideo -pix_fmt yuv420p -s:v 1920x1080 -i raw.yuv -vcodec libx264 video.mp4
 You can see an example of the time lapsed video here: