= Using "youtube-dl" to manage YouTube subscriptions

:ytsm-ann: https://old.reddit.com/r/DataHoarder/comments/9sg8q5/i_built_a_selfhosted_youtube_subscription_manager/
:ytsm-code: https://github.com/chibicitiberiu/ytsm
:ytdl: https://youtube-dl.org/

I've recently read the {ytsm-ann}[announcement] of a very nice
{ytsm-code}[self-hosted YouTube subscription manager].  I haven't used YouTube's
built-in subscriptions for a while now, and haven't missed it at all.  When I
saw the announcement, I considered writing about the solution I've built on top
of {ytdl}[youtube-dl].

== Background: the problem with YouTube

:net-giants: https://staltz.com/what-happens-when-you-block-internet-giants.html

In many ways, I agree with {net-giants}[André Staltz's view on data ownership
and privacy]:

____
I started with the basic premise that "I want to be in control of my data".
Sometimes that meant choosing when to interact with an internet giant and how
much I feel like revealing to them.  Most of times it meant not interacting with
them at all.  I don't want to let them be in full control of how much they can
know about me.  I don't want to be in autopilot mode.  (...) Which leads us to
YouTube.  While I was able to find alternatives to Gmail (Fastmail), Calendar
(Fastmail), Translate (Yandex Translate), _etc._ YouTube remains as the most
indispensable Google-owned web service.  It is really really hard to avoid
consuming YouTube content.  It was probably the smartest startup acquisition
ever.  My privacy-oriented alternative is to watch YouTube videos through Tor,
which is technically feasible but not polite to use the Tor bandwidth for these
purposes.  I'm still scratching my head with this issue.
____

Even though I don't use most alternative services he mentions, I do watch videos
from YouTube.  But I also feel uncomfortable logging in to YouTube with a Google
account, watching videos, creating playlists and similar things.

Using the mobile app is worse: you can't even block ads in there.  You're in
less control on what you share with YouTube and Google.

== youtube-dl

:other-sites: https://rg3.github.io/youtube-dl/supportedsites.html

youtube-dl is a command-line tool for downloading videos, from YouTube and
{other-sites}[many other sites]:

[source,shell]
----
$ youtube-dl https://www.youtube.com/watch?v=rnMYZnY3uLA
[youtube] rnMYZnY3uLA: Downloading webpage
[youtube] rnMYZnY3uLA: Downloading video info webpage
[download] Destination: A Origem da Vida _ Nerdologia-rnMYZnY3uLA.mp4
[download] 100% of 32.11MiB in 00:12
----

It can be used to download individual videos as showed above, but it also has
some interesting flags that we can use:

* `--output`: use a custom template to create the name of the downloaded file;
* `--download-archive`: use a text file for recording and remembering which
  videos were already downloaded;
* `--prefer-free-formats`: prefer free video formats, like `webm`, `ogv` and
  Matroska `mkv`;
* `--playlist-end`: how many videos to download from a "playlist" (a channel, a
  user or an actual playlist);
* `--write-description`: write the video description to a `.description` file,
  useful for accessing links and extra content.

Putting it all together:

[source,shell]
----
$ youtube-dl "https://www.youtube.com/channel/UClu474HMt895mVxZdlIHXEA" \
	--download-archive ~/Nextcloud/cache/youtube-dl-seen.conf \
	--prefer-free-formats \
	--playlist-end 20 \
	--write-description \
	--output "~/Downloads/yt-dl/%(uploader)s/%(upload_date)s - %(title)s.%(ext)s"
----

This will download the latest 20 videos from the selected channel, and write
down the video IDs in the `youtube-dl-seen.conf` file.  Running it immediately
after one more time won't have any effect.

If the channel posts one more video, running the same command again will
download only the last video, since the other 19 were already downloaded.

With this basic setup you have a minimal subscription system at work, and you
can create some functions to help you manage that:

[source,shell]
----
#!/bin/sh

export DEFAULT_PLAYLIST_END=15

download() {
	youtube-dl "$1" \
		--download-archive ~/Nextcloud/cache/youtube-dl-seen.conf \
		--prefer-free-formats \
		--playlist-end "$2" \
		--write-description \
		--output "~/Downloads/yt-dl/%(uploader)s/%(upload_date)s - %(title)s.%(ext)s"
}
export -f download


download_user() {
	download "https://www.youtube.com/user/$1" "${2-$DEFAULT_PLAYLIST_END}"
}
export -f download_user


download_channel() {
	download "https://www.youtube.com/channel/$1" "${2-$DEFAULT_PLAYLIST_END}"
}
export -f download_channel


download_playlist() {
	download "https://www.youtube.com/playlist?list=$1" "${2-$DEFAULT_PLAYLIST_END}"
}
export -f download_playlist
----

With these functions, you now can have a subscription fetching script to
download the latest videos from your favorite channels:

[source,shell]
----
#!/bin/sh

download_user     ClojureTV                            15
download_channel  'UCmEClzCBDx-vrt0GuSKBd9g'           100
download_playlist 'PLqG7fA3EaMRPzL5jzd83tWcjCUH9ZUsbX' 15
----

Now, whenever you want to watch the latest videos, just run the above script
and you'll get all of them in your local machine.

== Tradeoffs

=== I've made it for myself, with my use case in mind


[qanda]
Offline::
My internet speed it somewhat
reasonable{empty}footnote:[
  Considering how expensive it is and the many ways it could be better, but also
  how much it has improved over the last years, I say it's reasonable.
], but it is really unstable.  Either at work or at home, it's not uncommon to
loose internet access for 2 minutes 3~5 times every day, and stay completely
offline for a couple of hours once every week.
+
Working through the hassle of keeping a playlist on disk has payed off many,
many times.  Sometimes I even not notice when the connection drops for some
minutes, because I'm watching a video and working on some document, all on my
local computer.
+
There's also no quality adjustment for YouTube's web player, I always pick the
higher quality and it doesn't change during the video.  For some types of
content, like a podcast with some tiny visual resources, this doesn't change
much.  For other types of content, like a keynote presentation with text written
on the slides, watching on 144p isn't really an option.
+
If the internet connection drops during the video download, youtube-dl will
resume from where it stopped.
+
This is an offline first benefit that I really like, and works well for me.


Sync the "seen" file::
I already have a running instance of Nextcloud, so just dumping the
`youtube-dl-seen.conf` file inside Nextcloud was a no-brainer.
+
You could try putting it in a dedicated git repository, and wrap the script with
an autocommit after every run.  If you ever had a merge conflict, you'd simply
accept all changes and then run the following to tidy up the file:
+
[source,shell]
----
$ uniq youtube-dl-seen.conf > youtube-dl-seen.conf
----


Doesn't work on mobile::
My primary device that I use everyday is my laptop, not my phone.  It works well
for me this way.
+
Also, it's harder to add ad-blockers to mobile phones, and most mobile software
still depends on Google's and Apple's blessing.
+
If you wish, you can sync the videos to the SD card periodically, but that's a
bit of extra manual work.


=== The Good


[qanda]
Better privacy::
We don't even have to configure the ad-blocker to keep ads and trackers away!
+
YouTube still has your IP address, so using a VPN is always a good idea.
However, a timing analysis would be able to identify you (considering the
current implementation).


No need to self-host::
There's no host that needs maintenance.  Everything runs locally.
+
As long as you keep youtube-dl itself up to date and sync your "seen" file,
there's little extra work to do.


Track your subscriptions with git::
After creating a `subscriptions.sh` executable that downloads all the videos,
you can add it to git and use it to track metadata about your subscriptions.


=== The Bad


[qanda]
Maximum playlist size is your disk size::
This is a good thing for getting a realistic view on your actual "watch later"
list.  However I've run out of disk space many times, and now I need to be more
aware of how much is left.


=== The Ugly

We can only avoid all the bad parts of YouTube with youtube-dl as long as
YouTube keeps the videos public and programmatically accessible.  If YouTube
ever blocks that we'd loose the ability to consume content this way, but also
loose confidence on considering YouTube a healthy repository of videos on the
internet.


== Going beyond

Since you're running everything locally, here are some possibilities to be
explored:


=== A playlist that is too long for being downloaded all at once

You can wrap the `download_playlist` function (let's call the wrapper
`inc_download`) and instead of passing it a fixed number to the `--playlist-end`
parameter, you can store the `$n` in a folder (something like
`$HOME/.yt-db/$PLAYLIST_ID`) and increment it by `$step` every time you run
`inc_download`.

This way you can incrementally download videos from a huge playlist without
filling your disk with gigabytes of content all at once.


=== Multiple computer scenario

The `download_playlist` function could be aware of the specific machine that it
is running on and apply specific policies depending on the machine: always
download everything; only download videos that aren't present anywhere else;
_etc._


== Conclusion

youtube-dl is a great tool to keep at hand.  It covers a really large range of
video websites and works robustly.

Feel free to copy and modify this code, and send me suggestions of improvements
or related content.

== _Edit_

2019-05-22: Fix spelling.
