android: keep radio VAD blocked until AudioTrack plays the receive tail

tools/chatgui-android/app/src/main/java/com/utun/chat/data/NativeLib.kt

@@ -210,7 +210,7 @@ object NativeLib {
     fun radioSubscribers(groupId: Long): Int = nativeRadioSubscribers(groupId)
     fun radioAudioStart(groupId: Long, channels: Int): Boolean = nativeRadioAudioStart(groupId, channels)
     fun radioAudioFeed(groupId: Long, samples: ShortArray): Boolean = nativeRadioAudioFeed(groupId, samples)
-    fun radioAudioPull(groupId: Long, out: ShortArray): Int = nativeRadioAudioPull(groupId, out)
+    fun radioAudioPull(groupId: Long, out: ShortArray, playedFrames: Long): Int = nativeRadioAudioPull(groupId, out, playedFrames)
     fun radioAudioStop() { nativeRadioAudioStop() }
     fun radioCaptureStart(groupId: Long, channels: Int, vad: Boolean): Boolean = nativeRadioCaptureStart(groupId, channels, vad)
     fun radioCaptureStop() { nativeRadioCaptureStop() }
@@ -334,7 +334,7 @@ object NativeLib {
     private external fun nativeRadioSubscribers(groupId: Long): Int
     private external fun nativeRadioAudioStart(groupId: Long, channels: Int): Boolean
     private external fun nativeRadioAudioFeed(groupId: Long, samples: ShortArray): Boolean
-    private external fun nativeRadioAudioPull(groupId: Long, out: ShortArray): Int
+    private external fun nativeRadioAudioPull(groupId: Long, out: ShortArray, playedFrames: Long): Int
     private external fun nativeRadioAudioStop()
     private external fun nativeRadioCaptureStart(groupId: Long, channels: Int, vad: Boolean): Boolean
     private external fun nativeRadioCaptureStop()

tools/chatgui-android/app/src/main/java/com/utun/chat/data/RadioAudioEngine.kt

@@ -692,14 +692,32 @@ class RadioAudioEngine {
     private fun playLoop() {
         val frame = FRAME_SAMPLES * PLAY_CHANNELS
         val buf = ShortArray(frame)
-        val silence = ShortArray(frame)
         val frameNs = FRAME_MS * 1_000_000L   /* 20мс в наносекундах */
         var nextNs = System.nanoTime()
+        var previousHead = 0L
+        var playedFrames = 0L
+        val group = audioGroup
+        val track = audioTrack ?: return
+        LogManager.addLog("DEBUG", "radio", "playback progress tracking group=$group guard=200ms")
         while (playbackRunning) {
-            val track = audioTrack ?: return
-            val n = NativeLib.radioAudioPull(audioGroup, buf)
-            if (n > 0) track.write(buf, 0, n)
-            if (n < frame) track.write(silence, 0, frame - n)
+            /* AudioTrack возвращает unsigned 32-bit позицию; разворачиваем wrap (~25 часов @48k). */
+            val head = track.playbackHeadPosition.toLong() and 0xffffffffL
+            playedFrames += (head - previousHead) and 0xffffffffL
+            previousHead = head
+            val n = NativeLib.radioAudioPull(group, buf, playedFrames)
+            if (n < frame) buf.fill(0, n.coerceAtLeast(0), frame)
+            var written = 0
+            while (written < frame && playbackRunning) {
+                val count = track.write(buf, written, frame - written)
+                if (count <= 0) {
+                    if (playbackRunning) {
+                        LogManager.addLog("ERROR", "radio", "playback write failed group=$group rc=$count written=$written/$frame")
+                        mainHandler.post { if (audioTrack === track) stop() }
+                    }
+                    return
+                }
+                written += count
+            }
 
             /* абсолютный deadline: не даём Thread.sleep накопить систематический дрейф */
             nextNs += frameNs