moq-rs/moq-pub/README.md

moq-pub

A command line tool for publishing media via Media over QUIC (MoQ).

Expects to receive fragmented MP4 via standard input and connect to a MOQT relay.

ffmpeg ... - | moq-pub -i - -u https://localhost:4443

A note on the moq-pub code organization

• Media is responsible for reading from stdin and parsing MP4 boxes. It populates a MapSource of Tracks for which it holds the producer side, pushing segments of video/audio into them and notifying consumers via tokio watch async primitives.

• SessionRunner is where we create and hold the MOQT Session from the moq_transport library. We currently hard-code our implementation to use quinn as the underlying WebTranport implementation. We use a series of mpsc and broadcast channels to make it possible for other parts of our code to send/recieve control messages via that Session. Sending Objects is handled a little differently because we are able to clone the MOQT Session's sender wherever we need to do that.

• MediaRunner is responsible for consuming the Tracks that Media produces and populates. MediaRunner spawns tasks for each Track to .await new segments and then put the media data into Objects and onto the wire (via channels into SessionRunner). Note that these tasks are created, but block waiting un the reception of a MOQT SUBSCRIBE message before they actually send any segments on the wire. MediaRunner is also responsible for sending the initial MOQT ANNOUNCE message announcing the namespace for the tracks we will send.

• LogViewer as the name implies is responsible for logging. It snoops on some channels going in/out of SessionRunner and logs MOQT control messages.

Longer term, I think it'd be interesting to refactor everything such that the Media + MediaRunner bits consume an interface that's closer to what we'd like to eventually expose as a C FFI for consumption by external tools. That probably means greatly reducing the use of async Rust in the parts of this code that make up both sides of that interface boundary.

Invoking moq-pub:

Here's how I'm currently testing things, with a local copy of Big Buck Bunny named bbb_source.mp4:

$ ffmpeg -hide_banner -v quiet -stream_loop 0 -re -i ../media/bbb_source.mp4 -an -f mp4 -movflags empty_moov+frag_every_frame+separate_moof+omit_tfhd_offset - | RUST_LOG=moq_pub=info cargo run -- -i -

This relies on having moq-quinn (the relay server) already running locally in another shell.

Here's we can (eventually) run moq-pub without dropping the audio track (omit the -an I'm using above):

$ ffmpeg -hide_banner -v quiet -stream_loop 0 -re -i ../media/bbb_source.mp4 -f mp4 -movflags empty_moov+frag_every_frame+separate_moof+omit_tfhd_offset - | RUST_LOG=moq_pub=info cargo run -- -i -

Known issues

• Catalog track is a raw binary MP4 init segment rather than the newer JSON format moq-js now expects
• Doesn't handle EOF - just send it media forever with -stream_loop
• Probably still full of lots of bugs
• Various other TODOs you can find in the code