[Feature] Add DASH / CMAF support for adaptive, smooth video streaming

[Thinkscape]

I have searched the existing feature requests to make sure this is not a duplicate request.

• Yes

The feature

Sister feature to: #1674

Intro

DASH, also known as MPEG-DASH, is a similar standard to HLS but is not proprietary. It allows high-quality streaming of media content over the internet delivered from conventional HTTP web servers. Like HLS, DASH works by breaking the content into a series of small segments.

• Codec Agnostic: Unlike HLS, DASH is codec agnostic, meaning it can use any codec.
• Adaptive Streaming: It also supports adaptive streaming by allowing the client to choose from several different quality levels depending on available bandwidth.
• Manifest Files: DASH uses an XML-based manifest file (Media Presentation Description, MPD) that describes segment information for adaptive playback.

Why

• Support for slower connections (by serving lower quality video)
• Better streaming performance and resilience (i.e. on unstable connections)
• Adaptive streaming - could serve one of several quality versions, downgrade on slower connections.
• CDN-friendly - would allow i.e. CloudFlare to cache much smaller chunks (otherwise videos hit the MB limit which all plans have)
• Well supported in browsers and foundational to all video streaming services (Netflix, Youtube etc.)

How

Some reference:

• https://ffmpeg.org/ffmpeg-formats.html#dash-2
• https://blog.zazu.berlin/internet-programmierung/mpeg-dash-and-hls-adaptive-bitrate-streaming-with-ffmpeg.html
• https://github.com/shaka-project/shaka-player?tab=readme-ov-file#dash-features
• https://github.com/video-dev/hls.js/

Platform

• Server
• Web
• Mobile

[bo0tzz]

DASH doesn't magically do adaptive quality, right? IE we would still need to do dynamic transcoding on the server, making this a (partial) duplicate of #7666?

[bo0tzz]

We already have logic to serve the original file for images, so I think extending that to videos would be acceptable. @jrasm91 @mertalev thoughts?

[NicholasFlamy]

No one's asking me but I'll say that even without more than 2 video sources (original and transcoded) having it load the original on Wi-Fi and the transcoded not on Wi-Fi or when the connection is slow would be useful.

[mertalev]

I think it's conceptually fine to support displaying the original video. That being said, the logic for using the generated vs. original is pretty janky at the moment, so I think we'd want to refactor that area of the code before adding onto it.

[suurt8ll]

I think just a simple logic for serving the original video file on LAN and transcoded video when outside LAN would already be a huge improvement! Just giving my thoughts.

[Thinkscape]

I think just a simple logic for serving the original video file on LAN and transcoded video when outside LAN would already be a huge improvement! Just giving my thoughts.

This is similar to my suggestion above as low-hanging fruit, but the LAN detection could be janky (see how plex struggles with it) and would require new config options, some detection for setting the default (auto) setting etc.