恒定滞后喂料:换人切点零串行(用户拍板,静音轮替+无缝都治):

- 音频先进 pendingBuf,识别流滞后 feedLagSamples(1.5s)喂入;分析窗口保持实时(判定时机不变)
- 开口即查/SWITCH-FORCE 判定即置 cutRequested:录制线程冻结缓冲→强制断句→补喂冻结音频给新流,旧句在切点干净收尾;旧句已结算则直接补喂开新句;Stop 前补齐缓冲防丢尾
- 效果:静音轮替渗漏1.2s→≈0;无缝插话渗漏2~4s→≈1~2s(受缓冲深度约束);代价=全局实时字幕统一晚约1.5s;日志 ONSET-HOLD/ONSET-FLUSH 对账

app/src/main/java/com/k2fsa/sherpa/onnx/MainActivity.kt

@@ -219,6 +219,10 @@ class MainActivity : AppCompatActivity() {
     private val onsetEnabled = true
     private val onsetGapSamples = 9600      // 0.6s 前置静音
     private val onsetMinSamples = 19200     // 1.2s 开口窗
+    // 喂料恒定滞后(2026-09-16):识别流滞后 1.2s 喂入,切点前的音频可改道;
+    // 全局字幕延迟 ~1.2s 的代价换取换人零串行
+    private val feedLagSamples = 24000   // 1.5s:覆盖判定链(1.2s采集+计算)的
+    // 余量,开口渗漏≈0;全局字幕延迟即此值,调参范围 1.2~1.5s
     @Volatile private var onsetSeq = 0L     // 行切换/会话开始作废在途开口判定
     private var pendingOnsetLabel: String? = null // 主线程:下一新行预置标签
     private var pendingOnsetLabelAt = 0L          // 预置标签时间戳(过期作废)
@@ -230,6 +234,8 @@ class MainActivity : AppCompatActivity() {
     // 不再等停顿,直接强判 endpoint 断句。单窗毛刺(音量/瞬时)攒不满 2。
     @Volatile private var rollingLowStreak = 0
     @Volatile private var pendingForceEndpoint = false
+    // 滞后喂料的切点冻结请求(判定线程置位,录制线程消费,2026-09-16)
+    @Volatile private var cutRequested = false
     private val forceSwitchStreaks = 2
     // 强切冷却(仅 speakerCheckHandler 线程访问,无需 volatile)
     private var lastForceSwitchAtMs = 0L
@@ -630,6 +636,16 @@ class MainActivity : AppCompatActivity() {
         var newSinceCheck = 0
         var silenceRun = 0
         var onsetRun = 0   // 开口即查:静音后已累积的开口语音采样数
+        // 恒定滞后喂料(2026-09-16):音频先进 pendingBuf,滞后 feedLagSamples
+        // 再喂识别流/样本缓冲(窗口分析保持实时)。换人决定时冻结缓冲,
+        // 断句后补喂给新流——新人开头音频从不进入旧句子。
+        val pendingBuf = java.util.ArrayDeque<FloatArray>()
+        var pendingSamples = 0
+        var frozen = false
+        fun feedChunk(ch: FloatArray) {
+            pushChunk(ch)
+            stream.acceptWaveform(ch, sampleRate = sampleRateInHz)
+        }
 
         while (isRecording) {
             val ret = audioRecord?.read(buffer, 0, buffer.size)
@@ -639,11 +655,26 @@ class MainActivity : AppCompatActivity() {
                 val wasSilent = silenceRun >= onsetGapSamples
                 silenceRun = if (blockRms < silenceRms)
                     silenceRun + ret else 0
-                pushChunk(samples)
+                window.push(samples)   // 分析窗口实时;识别流滞后喂
-                window.push(samples)
+                if (!frozen && cutRequested) {
+                    cutRequested = false
+                    frozen = true
+                    if (sentenceId != -1L) pendingForceEndpoint = true
+                    Log.i(TAG, "ONSET-HOLD frozen pending=" +
+                            "${pendingSamples * 1000 / sampleRateInHz}ms")
+                }
+                pendingBuf.addLast(samples)
+                pendingSamples += samples.size
+                if (!frozen) {
+                    while (pendingSamples > feedLagSamples) {
+                        val head = pendingBuf.removeFirst()
+                        pendingSamples -= head.size
+                        feedChunk(head)
+                    }
+                }
 
                 // 开口即查(2026-09-16):≥0.6s 静音后的开口攒 1.2s 立即判一次
-                if (onsetEnabled && enableRollingSwitch && speakersEnabled) {
+                if (onsetEnabled && enableRollingSwitch && speakersEnabled && !frozen) {
                     if (blockRms >= silenceRms) {
                         if (wasSilent && onsetRun == 0) onsetRun = ret
                         else if (onsetRun > 0) onsetRun += ret
@@ -673,6 +704,7 @@ class MainActivity : AppCompatActivity() {
                                             " label=$label kind=" +
                                             (if (known != null) "known" else "new") +
                                             " active=${active ?: "-"}")
+                                    cutRequested = true
                                     uiHandler.post { onOnsetSwitch(label) }
                                 }
                             }
@@ -685,7 +717,7 @@ class MainActivity : AppCompatActivity() {
                 // P2(2026-09-11):跨句常驻检测,参考 embedding 为"行级"
                 // (appendNewLine 时重置)——新人开口后第一个周期内即可触发换行,
                 // 句间不再依赖 endpoint 的迟到判定
-                if (enableRollingSwitch && speakersEnabled) {
+                if (enableRollingSwitch && speakersEnabled && !frozen) {
                     newSinceCheck += ret
                     if (newSinceCheck >= checkStep) {
                         newSinceCheck = 0
@@ -808,6 +840,7 @@ class MainActivity : AppCompatActivity() {
                                                                         " streak>=$forceSwitchStreaks") +
                                                                     " label=$label" +
                                                                     " owner=sid$owner")
+                                                            cutRequested = true
                                                             uiHandler.post {
                                                                 onOnsetSwitch(label)
                                                             }
@@ -823,7 +856,6 @@ class MainActivity : AppCompatActivity() {
                     }
                 }
 
-                stream.acceptWaveform(samples, sampleRate = sampleRateInHz)
                 while (onlineRecognizer.isReady(stream)) {
                     onlineRecognizer.decode(stream)
                 }
@@ -909,9 +941,46 @@ class MainActivity : AppCompatActivity() {
                             uiHandler.post { closeOnsetLineIfPending() }
                         }
                     }
+                    // 冻结缓冲在断句/重置后补喂给新流(时间轴连续)
+                    if (frozen) {
+                        var drained = 0
+                        while (pendingBuf.isNotEmpty()) {
+                            val ch = pendingBuf.removeFirst()
+                            drained += ch.size
+                            feedChunk(ch)
+                        }
+                        pendingSamples = 0
+                        frozen = false
+                        Log.i(TAG, "ONSET-FLUSH " +
+                                "${drained * 1000 / sampleRateInHz}ms -> new stream")
+                    }
+                }
+
+                // 冻结时无句可断(旧句已结算)→ 直接补喂开新句
+                if (frozen && sentenceId == -1L) {
+                    var drained = 0
+                    while (pendingBuf.isNotEmpty()) {
+                        val ch = pendingBuf.removeFirst()
+                        drained += ch.size
+                        feedChunk(ch)
+                    }
+                    pendingSamples = 0
+                    frozen = false
+                    Log.i(TAG, "ONSET-FLUSH(no-sentence) " +
+                            "${drained * 1000 / sampleRateInHz}ms")
                 }
             }
         }
+        // Stop:补齐滞后缓冲(否则丢最后 ~1.2s),解码后再走软 endpoint
+        if (pendingBuf.isNotEmpty()) {
+            while (pendingBuf.isNotEmpty()) feedChunk(pendingBuf.removeFirst())
+            pendingSamples = 0
+            frozen = false
+        }
+        while (onlineRecognizer.isReady(stream)) {
+            onlineRecognizer.decode(stream)
+        }
+
         // Stop 兜底(软 endpoint):最后一句未完的转写同样走定格→判定→精修,
         // 否则丢半句 + 灰"未识别"行滞留(用户反馈 2026-09-11)
         if (sentenceId != -1L) {