webmetro

webmetro is a simple relay server for broadcasting a WebM stream from one uploader to many downloaders, via HTTP.

The initialization segment is remembered, so that viewers can join mid-stream.

Cluster timestamps are rewritten to be monotonic, so multiple (compatibly-encoded) webm files can be chained together without clients needing to reconnect.

Building

Dependencies & building are handed by Cargo:

cargo build --release

If you're feeling bold, you can let Cargo install it for you:

cargo install

Usage

Launch a relay server with the relay subcommand:

webmetro relay localhost:8080

At this point you can open http://localhost:8080/live in a web browser.

Next, a source client will need to POST or PUT a stream to that URL; a static file can be uploaded with the send subcommand:

webmetro send --throttle http://localhost:8080/live < file.webm

You can even glue together multiple files, provided they share the same codecs and track order:

cat 1.webm 2.webm 3.webm | webmetro send --throttle http://localhost:8080/live

You can use ffmpeg to transcode a non-WebM file or access a media device:

ffmpeg -i file.mp4 -deadline realtime -threads 4 -vb 700k -vcodec libvpx -f webm -live 1 - | webmetro send --throttle http://localhost:8080/live

(if the source is itself a live stream, you can leave off the --throttle flag)

Limitations

HTTPS is not supported yet. It really should be. (see "Nginx Proxying" below, though)
There aren't any access controls on either the source or viewer roles yet. (see "Nginx Proxying" below, though)
Currently the server only recognizes a single stream, at /live.
The server tries to start a viewer at a cluster containing a keyframe; it is not yet smart enough to ensure that the keyframe belongs to the video stream.
The server doesn't parse any metadata, such as tags; the Info segment is stripped out, everything else is blindly passed along.
The server drops any source that it feels uses too much buffer space. This is not yet configurable, though sane files probably won't hit the limit. (Essentially, clusters & the initialization segment can't individually be more than 2M)

Nginx Proxying

To get around the current lack of native HTTPS support, you can have nginx terminate the SSL connection; likewise you can have nginx handle access control.

The proxy block will need to include at least the following:

location /webmetro/ {
    # needed to stream PUT request bodies properly
    proxy_http_version 1.1;
    proxy_request_buffering off;
    client_max_body_size 0;

    # alternatively you may wish to bar PUT requests so only local clients can transmit
    # proxy_method GET;

    # proxy to a relay server that's only listening on localhost
    proxy_pass http://localhost:8080/;
}

This is also useful to simply have the same public port shared by webmetro and a nicely-formatted viewer page.

License

webmetro is licensed under the MIT license; see the LICENSE file.

3.2 KiB Raw Blame History