* sfu: forward the dependency descriptor for VP8 simulcast
libwebrtc sends VP8 with a one byte payload descriptor when it sends the
dependency descriptor, so a VP8 subscriber gets neither picture IDs nor the
descriptor and finds frame references by sequence number alone. Under loss
with temporal filtering it stalls until a key frame.
DDForwarder rewrites the publisher's descriptor for each forwarded packet:
frame numbers continue across simulcast layer switches and stream restarts,
the structure goes out with the current layer's key frame, and the active
decode targets follow the forwarded temporal layer.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
* sfu: keep VP8 descriptor frame numbers from going back
Rebase frame numbers only when a new stream would go back past the last
number sent: on a layer switch, a stream restart (also when it starts with a
delta frame) and a new forwarder on the same downtrack, which now carries
over the last number sent.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
* sfu: set VP8 descriptor decode targets from the packet's layer
The active decode targets use the temporal layer the packet is forwarded at,
not the selector's next layer on the last packet before a down switch. They
also go out on key frames, combined with the publisher's own mask.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
* sfu: carry the current active decode targets on every DD packet
The parser puts the stream's current mask on every packet, so a mask change
on a dropped packet still reaches the VP8 descriptor forwarder, which no
longer tracks the publisher's mask itself.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
* sfu: take the first DD active decode targets mask at any sequence number
A publisher whose first packet has RTP sequence number 0 never had its key
frame's mask applied, so every packet reported no active decode targets.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
* sfu/buffer: parse the dependency descriptor without allocating
Every VP9 and AV1 SVC packet allocated six objects in the dependency
descriptor parse: the descriptor, a clone of the frame template with
its three slices, a resolution copy, and a frame entity that took the
address of a parameter.
The pooled ExtDependencyDescriptor now owns the storage for the
descriptor, the template and the resolution, with fixed arrays for the
template's slices. The reader copies the matching template into that
storage.
Delta frame parse: 6 allocs, 176 B, 174 ns -> 0 allocs, 0 B, 122 ns.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
* sfu/dd: never copy a parsed frame into a structure template
A caller can hand Unmarshal a descriptor whose FrameDependencies points
at one of the structure's templates. Copying the packet's custom fields
into it would change the template for every later packet, so the reader
allocates a fresh template in that case.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
