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Reduce relay playback overhead

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James Magahern
2026-06-07 00:44:45 -07:00
parent a9b180f774
commit 0cb091cb53
5 changed files with 38 additions and 16 deletions
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README.md
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@@ -51,7 +51,7 @@ The app sets `FFMPEG_INPUT_SEEKABLE=0` by default so `ffmpeg` reads stream input
JPEG frames are dropped when the browser WebSocket falls behind instead of letting stale frames queue indefinitely. Tune the server-side backlog cap with `MAX_WS_BUFFER_BYTES`; the default is `524288`.
In single mode, audio output from `ffmpeg` is buffered before it is written to the browser so short HTTP backpressure pauses are less likely to stall frame generation. Tune the cap with `MAX_AUDIO_QUEUE_BYTES`; the default is `16777216`.
In single mode, audio output from `ffmpeg` is buffered before it is written to the browser so short HTTP backpressure pauses are less likely to stall frame generation. Tune the cap with `MAX_AUDIO_QUEUE_BYTES`; the default is `4194304`.
Playback uses `PLAYBACK_CONNECTION_MODE=split` by default. The Docker Compose example sets `PLAYBACK_CONNECTION_MODE=relay` so IPTV-style streams can be tested with one upstream connection.
@@ -61,9 +61,9 @@ Available playback modes:
- `relay`: One source connection from the backend, then the compressed input bytes are teed into separate audio and frame `ffmpeg` workers. This is intended for IPTV hosts that stop early or reject multiple active connections.
- `single`: One source connection and one `ffmpeg` worker with both audio and frame outputs. This is the simplest one-connection fallback, but audio and frame delivery can affect each other.
Finite-duration streams are treated as recorded video and become seekable once metadata is available. If the app is configured for `relay`, recorded streams switch to the seek-capable `split` path; live or unknown-duration streams stay in relay mode.
Finite-duration streams are treated as recorded video and become seekable once metadata is available. Metadata probing is enabled by default except in `relay`, where `METADATA_PROBE_ENABLED=0` avoids extra upstream connections. Set `METADATA_PROBE_ENABLED=1` if you want recorded relay sessions to become seekable and switch to the seek-capable `split` path.
Relay mode uses bounded per-worker input queues so one branch can briefly lag without immediately stalling the other. Tune the cap with `MAX_RELAY_BRANCH_QUEUE_BYTES`; the default is `16777216`.
Relay mode uses bounded per-worker input queues so one branch can briefly lag without immediately stalling the other. Tune the cap with `MAX_RELAY_BRANCH_QUEUE_BYTES`; the default is `8388608`.
## Tuning