Signal logger #558
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| package sip | ||
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| const signalLoggingFeatureFlag = "sip.signal_logging" |
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| // Copyright 2024 LiveKit, Inc. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
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| package sip | ||
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| import ( | ||
| "fmt" | ||
| "time" | ||
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| msdk "github.com/livekit/media-sdk" | ||
| "github.com/livekit/protocol/logger" | ||
| ) | ||
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| const ( | ||
| DefaultSignalMultiplier = float64(2) // Singnal needs to be at least 2 times the noise floor to be detected. | ||
| DefaultNoiseFloor = float64(25) // Use a low noise floor; The purpose is to detect any kind of signal, not just voice. | ||
| DefaultHangoverDuration = 1 * time.Second // Duration of silence that needs to elapse before we no longer consider it a signal. | ||
| ) | ||
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| // Keeps an internal state of whether we're currently transmitting signal (voice or noise), or silence. | ||
| // This implements msdk.PCM16Writer to inspect decoded packet content. | ||
| // Used to log changes betweem those states. | ||
| type SignalLogger struct { | ||
|
Contributor
There was a problem hiding this comment. We should consider moving it to |
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| // Configuration | ||
| log logger.Logger | ||
| next msdk.PCM16Writer | ||
| name string | ||
| hangoverDuration time.Duration // Time to stay in "signal" state after last signal to avoid flip-flopping. | ||
| signalMultiplier float64 // Threshold multiplier for signal to be detected. | ||
| noiseFloor float64 // Moveing average of noise floor. | ||
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| // State | ||
| lastSignalTime time.Time | ||
| lastIsSignal bool | ||
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| // Stats | ||
| framesProcessed uint64 | ||
| stateChanges uint64 | ||
| } | ||
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| type SignalLoggerOption func(*SignalLogger) error | ||
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| func WithSignalMultiplier(signalMultiplier float64) SignalLoggerOption { | ||
| return func(s *SignalLogger) error { | ||
| if signalMultiplier <= 1 { | ||
| return fmt.Errorf("signal multiplier must be greater than 1") | ||
| } | ||
| s.signalMultiplier = signalMultiplier | ||
| return nil | ||
| } | ||
| } | ||
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| func WithNoiseFloor(noiseFloor float64) SignalLoggerOption { | ||
| return func(s *SignalLogger) error { | ||
| if noiseFloor <= 0 { | ||
| return fmt.Errorf("noise floor min must be positive") | ||
| } | ||
| s.noiseFloor = noiseFloor | ||
| return nil | ||
| } | ||
| } | ||
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| func WithHangoverDuration(hangoverDuration time.Duration) SignalLoggerOption { | ||
| return func(s *SignalLogger) error { | ||
| if hangoverDuration <= 0 { | ||
| return fmt.Errorf("hangover duration must be positive") | ||
| } | ||
| s.hangoverDuration = hangoverDuration | ||
| return nil | ||
| } | ||
| } | ||
| func NewSignalLogger(log logger.Logger, name string, next msdk.PCM16Writer, options ...SignalLoggerOption) (msdk.PCM16Writer, error) { | ||
| s := &SignalLogger{ | ||
| log: log, | ||
| next: next, | ||
| name: name, | ||
| hangoverDuration: DefaultHangoverDuration, | ||
| signalMultiplier: DefaultSignalMultiplier, | ||
| noiseFloor: DefaultNoiseFloor, | ||
| lastSignalTime: time.Time{}, | ||
|
Contributor
There was a problem hiding this comment. No need to initialize explicitly. |
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| lastIsSignal: false, | ||
| framesProcessed: 0, | ||
| stateChanges: 0, | ||
| } | ||
| for _, option := range options { | ||
| if err := option(s); err != nil { | ||
| return next, err | ||
| } | ||
| } | ||
| return s, nil | ||
| } | ||
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| func (s *SignalLogger) String() string { | ||
| return fmt.Sprintf("SignalLogger(%s) -> %s", s.name, s.next.String()) | ||
| } | ||
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| func (s *SignalLogger) SampleRate() int { | ||
| return s.next.SampleRate() | ||
| } | ||
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| func (s *SignalLogger) Close() error { | ||
| if s.stateChanges > 0 { | ||
| s.log.Infow("signal logger closing", "name", s.name, "stateChanges", s.stateChanges) | ||
| } | ||
| return s.next.Close() | ||
| } | ||
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| // Calculates the mean absolute deviation of the frame. | ||
| func (s *SignalLogger) MeanAbsoluteDeviation(sample msdk.PCM16Sample) float64 { | ||
| if len(sample) == 0 { | ||
| return 0 | ||
| } | ||
| var totalAbs int64 | ||
| for _, v := range sample { | ||
| if v < 0 { | ||
| totalAbs += int64(-v) | ||
| } else { | ||
| totalAbs += int64(v) | ||
| } | ||
| } | ||
| return float64(totalAbs) / float64(len(sample)) | ||
|
Contributor
There was a problem hiding this comment. We could also consider calculating a median, it will be less affected by sudden spikes. |
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| } | ||
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| func (s *SignalLogger) WriteSample(sample msdk.PCM16Sample) error { | ||
| currentEnergy := s.MeanAbsoluteDeviation(sample) | ||
|
Contributor
There was a problem hiding this comment. Probably doesn't matter here, but energy is usually computed as a square of amplitude. Maybe rename to |
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| now := time.Now() | ||
| isSignal := currentEnergy > (s.noiseFloor * s.signalMultiplier) | ||
| if isSignal { | ||
| s.lastSignalTime = now | ||
| } | ||
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| s.framesProcessed++ | ||
| if s.framesProcessed > 10 { // Don't log any changes at first | ||
| if isSignal && isSignal != s.lastIsSignal { // silence -> signal: Immediate transition | ||
|
Contributor
There was a problem hiding this comment. This could potentially hit each frame, wouldn't it be too spammy? |
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| s.lastIsSignal = true | ||
| s.stateChanges++ | ||
| s.log.Infow("signal changed", "name", s.name, "signal", isSignal, "stateChanges", s.stateChanges) | ||
| } else if !isSignal && isSignal != s.lastIsSignal { // signal -> silence: Only after hangover | ||
| if now.Sub(s.lastSignalTime) >= s.hangoverDuration { | ||
| s.lastIsSignal = false | ||
| s.stateChanges++ | ||
| s.log.Infow("signal changed", "name", s.name, "signal", isSignal, "stateChanges", s.stateChanges) | ||
| } | ||
| } | ||
| } else { | ||
| s.lastIsSignal = isSignal | ||
| } | ||
| return s.next.WriteSample(sample) | ||
| } | ||
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It is okay to omit this change, map lookup will still work on nil value.