Match stream audio queue to device buffer and document playback ownership

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

@@ -12,6 +12,7 @@ internal class StreamAudioOutput(
     private val log: (String) -> Unit = {}
 ) {
     internal interface Sink {
+        val bufferFrames: Int
         val threshold: Int
         val head: Long
         val description: String
@@ -36,6 +37,7 @@ internal class StreamAudioOutput(
                 if (Build.VERSION.SDK_INT >= 31) track.setStartThresholdInFrames(1)
             } catch (e: Exception) { track.release(); throw e }
         }
+        override val bufferFrames: Int get() = track.bufferSizeInFrames
         override val threshold: Int get() = if (Build.VERSION.SDK_INT >= 31)
             minOf(track.startThresholdInFrames, track.bufferSizeInFrames) else track.bufferSizeInFrames
         override val head: Long get() = track.playbackHeadPosition.toLong() and 0xffffffffL
@@ -79,12 +81,13 @@ internal class StreamAudioOutput(
         }
         previousHead = raw
         val head = headEpoch + raw
+        val first = deviceHead == 0L && head > 0
         if (head > deviceHead) {
-            if (deviceHead == 0L) log("audio started delayMs=${(now - openedAt) / 1_000_000} $description")
             stalledSince = -1
         }
         deviceHead = head
         played = head.coerceAtMost(written)
+        if (first) log("audio started delayMs=${(now - openedAt) / 1_000_000} $description")
     }
 
     /** Ровно одна неблокирующая запись за итерацию; ожидание устройства не задерживает video pump. */
@@ -96,7 +99,8 @@ internal class StreamAudioOutput(
             log("audio ${if (hold) "paused" else "resumed"} $description")
         }
         if (hold) return
-        if (pending == null && written - played < maxOf(960, sink?.threshold ?: 1)) {
+        // Размер устройства уже учитывает его период обслуживания; 20ms могут быть меньше одного периода.
+        if (pending == null && written - played < (sink?.bufferFrames ?: 1)) {
             val pcm = pull()
             if (pcm != null) {
                 check(pcm.isNotEmpty() && pcm.size <= 960 && pcm.size % 2 == 0) { "Invalid stream PCM size=${pcm.size}" }

tools/chatgui-android/app/src/test/java/com/utun/chat/data/StreamAudioOutputTest.kt

@@ -6,6 +6,7 @@ import java.util.ArrayDeque
 
 class StreamAudioOutputTest {
     private class Device(override val threshold: Int = 1) : StreamAudioOutput.Sink {
+        override val bufferFrames = maxOf(960, threshold)
         override var head = 0L
         override val description: String get() = "fake threshold=$threshold"
         val samples = ArrayList<Short>()
@@ -59,6 +60,14 @@ class StreamAudioOutputTest {
         assertEquals(100L, p.output.written); assertEquals(0L, p.output.played)
     }
 
+    @Test fun feedsHardwareBufferEvenWhenStartThresholdIsSmall() {
+        val p = Player(); repeat(4) { p.input.add(ShortArray(960)) }
+        p.step(0); p.step(5); p.step(10)
+        assertEquals(960L, p.output.written); assertEquals(2, p.pulls)
+        p.device.head = 480; p.step(15)
+        assertEquals(1440L, p.output.written); assertEquals(3, p.pulls)
+    }
+
     @Test fun clockDoesNotAdvanceWithWallTimeAndStalledDeviceFails() {
         val p = Player(); p.input.add(ShortArray(960)); p.step(0); p.step(1999)
         assertEquals(0L, p.output.played)