claude
a99932b427
silero-vad replaces the energy threshold when -vad-model points at it. Everything after the speech decision is the same state machine: the speech hold, the silence hold, the length cap and the utterance buffer. The model window is 512 samples and the capture frame is 480, so silero.go re-chunks across frames. main.go claimed the two matched, which was true of silero v4. Stage two, the wake word, is not here. It needs a Russian keyword model that does not exist yet.
64 lines
2.8 KiB
Markdown
64 lines
2.8 KiB
Markdown
# silero-vad against the energy threshold in mavwaked
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*Measured 2026-08-09 on homesrv. V-487, stage one of two.*
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mavwaked decided an utterance had started by comparing frame energy to an
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adaptive floor. That answers "is this frame loud". A fan, a door and a
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television are all loud, and every utterance mavwaked accepts becomes a turn.
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silero-vad answers "is this frame speech". It is 2.3MB of ONNX and it replaces
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the comparison and nothing else. The speech hold, the silence hold, the length
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cap and the utterance buffer are the same state machine either way.
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## What it declines
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Speech is the four piper fixtures `mavsttd` already scores against, so nothing
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of the owner's voice is committed. Non-speech is white noise at the same RMS as the clip beside it. That is the
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cheapest thing that fools an energy floor.
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| clip | silero, speech frames on speech | silero on noise | energy on noise |
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|---|---|---|---|
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| ru_fact.wav | 59 | 0 | 68 |
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| ru_query.wav | 69 | 0 | 79 |
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| ru_reminder.wav | 80 | 0 | 89 |
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| en_act.wav | 90 | 0 | 99 |
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The energy threshold accepts every noise clip as a complete utterance. Silero
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calls not one frame of any of them speech, and still hears all four spoken
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clips. `TestSileroHearsSpeechAndDeclinesNoise` is that table.
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White noise is a floor, not a proof. It says nothing about a television, which
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is speech, or about a fan, which is narrowband. Those need room recordings and
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this box has none.
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## What it costs
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`BenchmarkSileroFrame` on the homesrv laptop (Ryzen 5 5600U), one 30ms frame
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through the model including the re-chunking:
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509µs per frame
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That is 1.7% of one core, on the slower of the two machines. The detector runs
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on the workstation beside the microphone, never on the GPU. This number is what
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says it does not need one.
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## The window is 512 samples, not 480
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`cmd/mavwaked/main.go` claimed the frame contract matched silero's input
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exactly. That was true of silero v4. Version 5 takes exactly 512 samples at 16kHz, plus 64 samples of context from
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the previous window. So `sileroVAD` buffers across capture frames, and a frame
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completing no window inherits the previous probability. `TestSileroRechunksAcrossFrames` pins it.
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## Still an energy gate by default
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`-vad-model` is empty in the code default, so a deployment that does not pass
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it runs exactly what shipped before. Barge-in is untouched and deliberately so. It reads frame energy while she is
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speaking, which is a different question from whether the frame is speech.
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## Not done here
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The wake word. This is stage one of the two V-487 asks for. The second needs a
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keyword model that does not exist yet. The pretrained openWakeWord keywords are
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English, and a Russian one has to be trained. Until then anything spoken near
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the microphone still becomes a turn. It is now merely required to be speech.
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