Broadcast

msf.Broadcast is an optional helper that integrates an MSF catalog with moqt.TrackHandler routing. It manages the catalog snapshot and per-track handlers together, automatically serving the catalog track and dispatching subscriptions to the appropriate handler.

Create a Broadcast

    catalog := msf.Catalog{
        Version: 1,
        Tracks: []msf.Track{
            {Name: "video", Packaging: msf.PackagingLOC, Role: msf.RoleVideo},
            {Name: "audio", Packaging: msf.PackagingLOC, Role: msf.RoleAudio},
        },
    }

    broadcast, err := msf.NewBroadcast(catalog)
    if err != nil {
        // handle error
    }

The catalog is validated before the broadcast is created. You can also start with a zero-value Broadcast and call SetCatalog later.

msf.Broadcast

func NewBroadcast(catalog Catalog) (*Broadcast, error)
func (b *Broadcast) Catalog() Catalog
func (b *Broadcast) CatalogBytes() ([]byte, error)
func (b *Broadcast) CatalogTrackName() moqt.TrackName
func (b *Broadcast) SetCatalog(catalog Catalog) error
func (b *Broadcast) RegisterTrack(track Track, handler moqt.TrackHandler) error
func (b *Broadcast) RemoveTrack(name moqt.TrackName) bool
func (b *Broadcast) Handler(name moqt.TrackName) moqt.TrackHandler
func (b *Broadcast) ServeTrack(tw *moqt.TrackWriter)

Register Tracks

    err := broadcast.RegisterTrack(
        msf.Track{Name: "video", Packaging: msf.PackagingLOC, Role: msf.RoleVideo},
        videoHandler,
    )

RegisterTrack adds a track to the catalog and associates a moqt.TrackHandler with it. If a track with the same name already exists, it is replaced. The catalog is validated after modification.

The reserved catalog track name ("catalog" by default) cannot be used.

Remove Tracks

    removed := broadcast.RemoveTrack("old-video")

RemoveTrack removes the named track and its handler from the broadcast. Returns true if the track was present.

Use as TrackHandler

msf.Broadcast implements moqt.TrackHandler, so it can be published directly:

    mux := moqt.DefaultMux
    mux.Publish("/live", broadcast)

Subscriptions to the catalog track name are served automatically with the current catalog snapshot serialized as JSON. All other subscriptions are routed to the registered per-track handler.

Update Catalog

    err := broadcast.SetCatalog(newCatalog)

SetCatalog replaces the catalog snapshot atomically. Tracks present in the old catalog but absent in the new one are automatically removed along with their handlers.

Catalog Track

The catalog is served as a special track (default name: "catalog"). When a subscriber requests this track, the current catalog snapshot is serialized as JSON and written as a single group with one frame.

    name := broadcast.CatalogTrackName() // "catalog"

The default catalog track name is msf.DefaultCatalogTrackName.