feel free download to your computer and share around if this help!

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handbrake ~ compress
==============
1. most default settings match input video, but check for crop just in case
2. set constant framerate, same as source
3. set video quality as 23 or higher - higher number = more artifacts, so still keep fairly low (default usually around 21)
4. check that audio is intact (may not be if start from .avi)
5. set name, location, and start encode :)

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kdenlive ~ video to mp3
==============
1. in project bin (left column), right click and add clip. choose video to convert
2. drag this video to timeline below (V1/V2/etc.)
3. in menu bar at top, select project -> render
4. in render menu, scroll until see "audio only"
5. select format, give name, and press "render to file"

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youtube-dl ~ choose lower resolution
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why do this? if quality not important, if want smaller file, if want shorter download time
    youtube-dl -f 'best[height<=###][ext=...]' URL
    where ### is resolution (360, 720, etc.) and ext is extension (mp4, webm, etc)

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youtube-dl ~ embed captions
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first check for captions:
    youtube-dl --list-sub URL
this give list for all possible caption formats. look at very bottom:
if "URL has no subtitles":
    youtube-dl --format [mp4/mkv/webm] --write-auto-sub --embed-subs URL
    unfortunately find lately this have bad habit of barf whole subtitle file on screen at once, which not very helpful. 
    still include because have better results in past, and maybe you will too.
if "Available subtitles for URL" and "Language formats":
    youtube-dl --format [mp4/mkv/webm] --write-sub --sub lang ## --embed-subs URL
    where ## is language code, like en for english

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youtube-dl ~ take only audio
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note: you need ffmpeg/ffprobe or avconv/avprobe for this
    youtube-dl -x --audio-format ... URL
    where ... is extension
    
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youtube-dl ~ take only part from video
==============
important: youtube-dl still download whole video, cut only happen in post process.
still, can be helpful if you prefer avoid edit after fact.
    --postprocessor-args
    "-ss HH:MM:SS - start at this time code, and
    -to HH:MM:SS" - end at this time code, OR
    -t HH:MM:SS" - take this length from video after start
youtube-dl --postprocessor-args "-ss 00:00:15 -to 01:05:00" URL - take from 0 hours, 0 minutes, 15 seconds, and go until 1 hour, 5 minutes, 0 seconds
youtube-dl --postprocessor-args "-ss 00:00:15 -t 00:45:30" URL - take from 0 hours, 0 minutes, 15 seconds, and continue for 45 minutes, 30 seconds

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youtube-dl ~ whole options list
==============
https://github.com/ytdl-org/youtube-dl#options