Domagoj Zecevic
1 month ago
7 changed files with 342 additions and 162 deletions
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package com.dzecevic.babymonitor |
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import android.media.AudioFormat |
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import android.media.AudioRecord |
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import android.media.MediaRecorder |
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import android.media.audiofx.AcousticEchoCanceler |
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import android.media.audiofx.AutomaticGainControl |
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import android.media.audiofx.NoiseSuppressor |
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import android.util.Log |
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import java.util.concurrent.atomic.AtomicBoolean |
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class AudioRecorder( |
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private val sampleRate: Int = 16000 |
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) { |
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private var record: AudioRecord? = null |
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private val running = AtomicBoolean(false) |
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private var thread: Thread? = null |
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fun start() { |
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if (running.getAndSet(true)) return |
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val minBuf = AudioRecord.getMinBufferSize( |
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sampleRate, |
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AudioFormat.CHANNEL_IN_MONO, |
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AudioFormat.ENCODING_PCM_16BIT |
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) |
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// Target ~40ms buffer (low latency but stable) |
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val bufSize = (minBuf * 2).coerceAtLeast(sampleRate / 25 * 2) |
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record = AudioRecord( |
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MediaRecorder.AudioSource.VOICE_COMMUNICATION, // MUCH better than MIC |
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sampleRate, |
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AudioFormat.CHANNEL_IN_MONO, |
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AudioFormat.ENCODING_PCM_16BIT, |
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bufSize |
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) |
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val r = record ?: return |
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if (r.state != AudioRecord.STATE_INITIALIZED) { |
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Log.e("AudioRecorder", "AudioRecord not initialized") |
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running.set(false) |
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return |
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} |
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r.startRecording() |
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// Disable latency-causing DSP if possible |
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try { |
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NoiseSuppressor.create(r.audioSessionId)?.enabled = false |
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AutomaticGainControl.create(r.audioSessionId)?.enabled = false |
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AcousticEchoCanceler.create(r.audioSessionId)?.enabled = false |
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} catch (_: Exception) {} |
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thread = Thread { |
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val buf = ByteArray(1024) // small chunk = low latency |
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while (running.get()) { |
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val n = r.read(buf, 0, buf.size) |
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if (n > 0) { |
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// Optional debug level meter |
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/* |
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var max = 0 |
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var i = 0 |
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while (i + 1 < n) { |
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val lo = buf[i].toInt() and 0xff |
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val hi = buf[i + 1].toInt() |
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val sample = (hi shl 8) or lo |
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max = max.coerceAtLeast(kotlin.math.abs(sample)) |
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i += 2 |
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} |
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Log.d("AUDIO", "level=$max") |
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*/ |
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FrameStoreAudio.latestPcm.set(buf.copyOf(n)) |
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} |
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} |
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}.apply { |
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isDaemon = true |
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start() |
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} |
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} |
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fun stop() { |
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running.set(false) |
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try { thread?.join(300) } catch (_: Exception) {} |
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thread = null |
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try { |
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record?.stop() |
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record?.release() |
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} catch (_: Exception) {} |
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record = null |
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} |
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} |
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@ -0,0 +1,7 @@ |
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package com.dzecevic.babymonitor |
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import java.util.concurrent.LinkedBlockingQueue |
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object AudioStore { |
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val audioQueue = LinkedBlockingQueue<ByteArray>(50) |
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} |
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@ -0,0 +1,7 @@ |
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package com.dzecevic.babymonitor |
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import java.util.concurrent.atomic.AtomicReference |
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object FrameStoreAudio { |
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val latestPcm = AtomicReference<ByteArray?>(null) |
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} |
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