57 lines
1.6 KiB
Markdown
57 lines
1.6 KiB
Markdown
# Architecture
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## Layers
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1. Capture
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- Hardware: ATSC antennas -> HDHomeRun or Linux IPTV capture devices.
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- Output: MPEG-TS or ATSC 3.0 streams.
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2. Normalize
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- Demux and normalize timestamps.
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- Select program IDs and identify audio/video tracks.
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3. Deterministic transcode
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- Encode with a fixed profile (codec, GOP, bitrate, keyframe cadence).
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- Emit fixed-duration chunks with stable ordering.
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- Hash chunks to produce content identifiers.
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4. MoQ publish
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- Map each channel to a track namespace.
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- Each chunk becomes a MoQ object in a group.
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- Objects are named and addressed deterministically.
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5. Relay mesh
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- Relays cache objects and announce tracks.
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- iroh provides programmable topology and peer routing.
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- Multiple relays can serve identical objects.
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6. Playback
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- Desktop: Tauri app that subscribes to tracks.
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- CLI: debugging, inspection, and headless clients.
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- Web: static site that connects to a relay gateway.
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## Roles
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- Runner: owns capture + transcode + publish.
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- Chopper: executes deterministic chunking profiles.
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- Relay: stores and forwards MoQ objects.
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- Manager: configures nodes and applies policy.
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- Provisioner: bootstraps nodes and manages deployment.
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## Determinism
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- The same input with the same profile should yield identical chunks.
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- Chunk hashes are the primitive for availability and de-duplication.
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- Deterministic names allow relays to converge without coordination.
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## Time synchronization
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- Chunk boundaries are derived from PCR and, when available, broadcast UTC (ATSC STT / DVB TDT/TOT).
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- Unsynced sources remain source-scoped until broadcast time is present.
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- Discontinuities force a new chunk group boundary.
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