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peertube/FAQ.md
Mark Van den Borre a5c9fa1051
Update FAQ.md wrt performance estimates and strategies (#3246) 
Co-authored-by: Rigel Kent <sendmemail@rigelk.eu>
2020-11-06 15:27:37 +01:00

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FAQ

Why did you create PeerTube?

We can't build a FOSS video streaming alternative to YouTube, Dailymotion, Vimeo... with centralized software. One organization alone may not have enough money to pay for bandwidth and video storage of its servers.

Our stance is that only a decentralized network of servers can provide an acceptable answer to technical issues (bandwidth, transcoding expenses, etc.) and social answers (need for a particular moderation policy, preserving content, etc.).

While a paragraph is not enough to answer all these problems, PeerTube has very early prided itself on using a contributory design, both for creating communities as federated nodes (as Mastodon for example), and for seeding videos (instances can seed each other's videos). But that's not enough because one video could become popular and overload the server. That is why we need to use a P2P protocol to limit the server load. Thanks to WebTorrent, we can use BitTorrent inside most modern web browsers, and users become seeds as the video gets more viewers.

I don't like the name "PeerTube"

PeerTube is just the name of the software. You can install it on your server, and choose a name you want. For example, this instance is named "Framatube".

If nobody watches a video, is it seeded?

Yes, the origin server always seeds videos uploaded on it thanks to Webseed. It can also be helped by other servers using redundancy.

What is WebSeed?

It is a BitTorrent extension that allows a server to seed a file through HTTP. It just needs to statically serve a file, then the clients will request chunks with a Content-Range HTTP header.

If a client requests each chunk of a video through HTTP, will the server be overloaded?

Not really. Reverse proxies like Nginx handle static file requests very well. In my tests, it can send chunks at 10MB/s without consuming more than 5% CPU on a very small VPS.

Will an index of all the videos of servers you follow be too large for small servers?

In our benchmarks, 1,000,000 videos consume around 2GB of PostgreSQL storage. We think that is acceptable for a video platform.

Which container formats can I use for the videos I want to upload?

WEBM, MP4 or OGV videos are supported by default (they are streamable formats), but instance administrators can additionally enable support for MKV, MOV, AVI and FLV formats when transcoding is enabled on their instance.

I want to change my domain name, how can I do that?

It's not officially supported, but you can try the update-host script: https://docs.joinpeertube.org/#/maintain-tools?id=update-hostjs

Why do we have to put our Twitter username in the PeerTube configuration?

You don't have to: we set a default value if you don't have a Twitter account. We need this information because Twitter requires an account for links share/videos embed on their platform.

How are video views counted?

Your web browser sends a view to the server after 30 seconds of playback. If a video is less than 30 seconds in length, a view is sent after 75% of the video. After giving a view, that IP address cannot add another view in the next hour. Views are buffered, so don't panic if the view counter stays the same after you watched a video.

Should I have a big server to run PeerTube?

PeerTube should run happily on a virtual machine with 2 threads/vCPUs, at least 1 Gb of RAM and enough storage for videos. In terms of bandwidth, a lot will depend on which PeerTube instances you federate with and what your relation with them is (more about that below).

As a real life example, the PeerTube demonstration server https://peertube.cpy.re runs on 2 vCores and 2GB of RAM. Average consumption is:

  • CPU: nginx ~ 20%, peertube ~ 10%, postgres ~ 1%, redis ~ 3%
  • RAM: nginx ~ 6MB, peertube ~ 120MB, postgres ~ 10MB, redis ~ 5MB

CPU

Except for video transcoding, a PeerTube instance is not CPU bound. Neither Nginx, PeerTube itself, PpostgreSQL nor Redis require a lot of computing power. If it were only for those, one could easily get by with just one thread/vCPU.

You will hugely benefit from at least a second thread though, because of transcoding. Transcoding is very cpu intensive. It serves two purposes on a PeerTube instance: it ensures all videos can be played optimally in the web interface, and it generates different resolutions for the same video. PeerTube support for offloading transcoding to other machines is being discussed, but not yet implemented. See https://github.com/Chocobozzz/PeerTube/issues/947 .

RAM

1 Gb of RAM should be plenty for a basic PeerTube instance, which usually takes at most 150 Mb in RAM. The only reason you might want more would be if you colocate your Redis or PostgreSQL services on a non-SSD system.

Storage

There are two important angles to storage: disk space usage and sustained read speed.

To make a rough estimate of your disk space usage requirements, you want to know the answer to three questions:

  • What is the total size of the videos you wish to stream?
  • Do you want to enable transcoding? If so, do you want to provide multiple resolutions per video? Try this out with a few videos and you will get an idea of how much extra space is required per video and estimate a multiplication factor for future space allocation.
  • Which sharing mechanisms do you want to enable? Just WebTorrent, or also HLS with p2p? If you want both, this will double your storage needs.

In terms of read speed, you want to make sure that you can saturate your network uplink serving PeerTube videos. This should not be a problem with SSD disks, whereas traditional HDD should be accounted for: typical sustained read rates for a well tuned system with a 7200rpm hard disk should hover around 120 MB/s or 960 Mbit/s. The latter should be enough for a typical 1 Gbit/s network uplink.

Network

A rough estimate of a traditional server's video streaming network capacity is usually quite straightforward. You simply divide your server's available bandwidth by the average bandwidth per stream, and you have an upper bound.

Take a server for example with a 1 Gbit/s uplink for example pushing out 1080p60 streams at 5 Mbit/s per stream. That means the absolute theoretical upper capacity bound is 200 simultaneous viewers if your server's disk i/o can keep up. Expect a bit less in practice.

But what if you need to serve more users? That's where PeerTube's federation feature shines. If other PeerTube instances following yours, chances are they have decided to mirror part of your instance! The feature is called "server redundancy" and caches your most popular videos to help serve additional viewers. While viewers themselves contribute a little additional bandwidth while watching the video in their browsers (mostly during surges), mirroring servers have a much greater uplink and will help your instance with sustained higher concurrent streaming.

If all your preparations and friends' bandwidth is not enough, you might prefer serving files from a CDN ; see our remote storage guide.

Can I seed videos with my classic BitTorrent client (Transmission, rTorrent...)?

Yes you can, but you won't be able to send data to users that watch the video in their web browser. The reason is they connect to peers through WebRTC whereas your BitTorrent client uses classic TCP/UDP. You can check if your BitTorrent client supports WebTorrent in this issue: https://github.com/webtorrent/webtorrent/issues/369

Why host on GitHub and Framagit?

The project was initially hosted on GitHub by Chocobozzz. A full migration to Framagit would be ideal now that Framasoft supports PeerTube, but it would take a lot of time and is an ongoing effort.

Are you going to use the Steem blockchain?

Short answer: no, since like most appchains/votechains, it modifies the dynamic of creation, and as such cannot be integrated into mainline PeerTube. Read more about that in the dedicated section.

Long answer is that the Steem blockchain goes astray of its promises of fairness and decentralization: the deliberate relaunching of the currency to ensure centralization, and the stake-based voting power, makes manipulation by wealthy users inevitable (source here). Worse, money generated primarily goes to stakeholders (source here ). For more information, read the complete whitepaper analysis done by Tone Vays.

Are you going to support advertisements?

Short answer: no, we don't want advertisers to dictate which content should be financed. That would modify the dynamic of creation; as such it cannot be integrated into mainline PeerTube. Read more about that in the dedicated section.

The long answer is probably more subtle. YouTube has shaped generations of video creators by making it easy to place ads; but making big money with the platform can be a challenge. A typical video ad runs between .10 and .30 per 1000 views (as of March 2018). More than 70% of video creators use ads as the main way to make money on YouTube, yet less than 3% of video creators make a living out of their YouTube activity (with partnerships and commissions, otherwise counting only ad revenue it drops to 1%). Read more about it in the 2018 study by Mathias Bärtl, YouTube channels, uploads and views: A statistical analysis of the past 10 years. To the best of our knowledge, small and medium-community creators are better off getting support from their community on platforms such as Liberapay, Tipeee or Patreon. Moreover, don't forget that advertisers already pay considering YouTube's large user base; with PeerTube's way smaller user base and refusal of user profiling, a pay-per-view that's lower than YouTube's could only be expected.

What is "creation dynamic" and why not modify it?

We define creation dynamic as the way any original content, regardless of its monetary value, is created and incentivized. We want to stay neutral by limiting the influence of our platform on authors as much as possible. We are not curators, and want to limit the scope of PeerTube instance owners and administrators' responsibilities to moderation tasks only.

If you still want to use a functionality potentially altering that state of things, then you could interface with our upcoming plug-in system, which will be the place to integrate such features in the near future.

With that being said, know that we are not against these features per se. We are always open to discussion about potential PRs bringing in features, even of that kind. But we certainly won't dedicate our limited resources to develop them ourselves when there is so much to be done elsewhere.

I have found a security vulnerability in PeerTube. Where and how should I report it?

We have a policy for contributions related to security. Please refer to SECURITY.md

Does PeerTube ensure federation compatibility with previous version?

We try to keep compatibility with the latest minor version (2.3.1 with 2.2 for example). We don't have resources to keep compatibility with other versions.