90 lines
3.6 KiB
Markdown
90 lines
3.6 KiB
Markdown
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# warp
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Live media delivery protocol utilizing QUIC streams.
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## How
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Warp works by delivering each audio and video segment as a separate QUIC stream. These streams are assigned a priority such that old video will arrive last and can be dropped. This avoids buffering in many cases, offering the viewer a potentially better experience.
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## Browser Support
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This demo currently only works on Chrome for two reasons:
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1. WebTransport support.
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2. [https://github.com/whatwg/html/issues/6359](Media underflow behavior).
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### Specification
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See the [https://datatracker.ietf.org/doc/draft-lcurley-warp/](Warp draft). This demo includes a few custom messages.
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## Setup
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### Software
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* Go
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* ffmpeg
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* openssl
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* Chrome Canary
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### Media
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This demo simulates a live stream by reading a file from disk and sleeping based on media timestamps. Obviously you should hook this up to a real live stream to do anything useful
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Download your favorite media file:
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```
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wget http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4 -O media/combined.mp4
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```
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Use ffmpeg to create a LL-DASH playlist. This creates a segment every 2s and MP4 fragment every 50ms.
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```
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ffmpeg -i media/combined.mp4 -f dash -use_timeline 0 -r:v 24 -g:v 48 -keyint_min:v 48 -sc_threshold:v 0 -tune zerolatency -streaming 1 -ldash 1 -seg_duration 2 -frag_duration 0.01 -frag_type duration media/fragmented.mpd
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```
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You can increase the `frag_duration` (microseconds) to slightly reduce the file size in exchange for higher latency.
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### TLS
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Unfortunately, QUIC mandates TLS and makes local development difficult.
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#### Existing
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If you have a valid certificate you can use it instead of self-signing. The go binaries take a `-cert` and `-key` argument.
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Skip the remaining steps in this section and use your hostname instead of `localhost.warp.demo`.
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#### Self-Signed
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Generate a self-signed certificate for local testing:
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```
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./cert/generate
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```
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This creates `cert/localhost.warp.demo.crt` and `cert/localhost.warp.demo.key`.
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#### CORS
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To have the browser accept our self-signed certificate, you'll need to add an entry to `/etc/hosts`.
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```
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echo '127.0.0.1 localhost.warp.demo' | sudo tee -a /etc/hosts
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```
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#### Chrome
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Now we need to make Chrome accept these certificates, which normally would involve trusting a root CA but this was not working with WebTransport when I last tried.
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Instead, we need to run a *fresh instance* of Chrome, instructing it to allow our self-signed certificate. This command will not work if Chrome is already running, so it's easier to use Chrome Canary instead. This command also needs to be executed in the project root because it invokes `./cert/fingerprint`.
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Launch a new instance of Chrome Canary:
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```
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/Applications/Google\ Chrome\ Canary.app/Contents/MacOS/Google\ Chrome\ Canary --origin-to-force-quic-on="localhost.warp.demo:4443" --ignore-certificate-errors-spki-list="`./cert/fingerprint`" https://localhost.warp.demo:4444
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```
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Note that this will open our web server on `localhost.warp.demo:4444`, which is started in the next section.
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### Warp Server
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The Warp server defaults to listening on UDP 4443. It supports HTTP/3 and WebTransport, pushing media over WebTransport streams once a connection has been established. A more refined implementation would load content based on the WebTransport URL or some other messaging scheme.
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```
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cd server
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go run ./warp-server
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```
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### Web Server
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The web assets need to be hosted with a HTTPS server. If you're using a self-signed certificate, you will need to ignore the security warning in Chrome (Advanced -> proceed to localhost.warp.demo).
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```
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cd client
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yarn serve
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```
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These can be accessed on `https://localhost.warp.demo:4444` by default.
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