Merge pull request #2584 from vitorpamplona/claude/optimize-video-loading-5opqr

Optimize video playback with warm player pool and buffer tuning

amethyst/src/main/java/com/vitorpamplona/amethyst/AppModules.kt

@@ -525,10 +525,16 @@ class AppModules(
             }
         }
 
-        // initializes diskcache on an IO thread.
+        // Warms the video cache off the main thread. SimpleCache's constructor opens a SQLite
+        // index over StandaloneDatabaseProvider and walks every cached span on disk — up to a
+        // few hundred ms on a populated 4 GB cache — so leaving it for the first session's
+        // onGetSession would do that work on the main thread. The short delay keeps the IO
+        // dispatcher free for the urgent first-paint work above (account load, image loader,
+        // ui state, robohash) while still landing the warmup well before a typical user can
+        // scroll to and tap a video. The previous 10 s delay was long enough that a fast user
+        // (or a deep link) could lose the lazy { } race and trigger main-thread init.
         applicationIOScope.launch {
-            // Prepares video cache later
-            delay(10_000)
+            delay(1_500)
             videoCache
         }
     }

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/GetVideoController.kt

@@ -21,10 +21,11 @@
 package com.vitorpamplona.amethyst.service.playback.composable
 
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
 import androidx.compose.ui.platform.LocalContext
-import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import androidx.media3.common.Player
 import com.vitorpamplona.amethyst.service.playback.composable.mediaitem.LoadedMediaItem
 import com.vitorpamplona.amethyst.service.playback.pip.BackgroundMedia
 import com.vitorpamplona.amethyst.service.playback.service.PlaybackServiceClient
@@ -49,25 +50,43 @@ fun GetVideoController(
             ).onEach { state ->
                 Log.d("PlaybackService") { "Controller instance: ${state.controller}" }
 
-                if (BackgroundMedia.isPlaying()) {
-                    // There is a video playing, start this one on mute.
-                    state.controller.volume = 0f
-                    Log.d("PlaybackService", "OnEach Muted due to BackgroundMedia.isPlaying")
-                } else {
-                    // There is no other video playing. Use the default mute state to
-                    // decide if sound is on or not.
-                    state.controller.volume = if (muted) 0f else 1f
-                    Log.d("PlaybackService") { "OnEach $muted" }
+                // The default ExoPlayer volume is 1f and the MediaSessionPool reset lambda
+                // sets it to 0f when the player is acquired, so the controller arrives at 0f.
+                // Read first and only push an IPC if the value actually needs to change —
+                // with several feed videos preloading at once each volume= write was a
+                // round-trip to the service for nothing.
+                val targetVolume =
+                    when {
+                        BackgroundMedia.isPlaying() -> 0f
+                        muted -> 0f
+                        else -> 1f
+                    }
+                if (state.controller.volume != targetVolume) {
+                    state.controller.volume = targetVolume
+                    Log.d("PlaybackService") { "OnEach volume=$targetVolume" }
                 }
 
                 if (play) {
                     state.controller.playWhenReady = true
                 }
 
-                state.controller.setMediaItem(mediaItem.item)
-                state.controller.prepare()
+                // Warm-pool fast path: when the underlying ExoPlayer was retained paused-with-
+                // buffer for this exact MediaItem, the MediaController's local mirror already
+                // shows the matching mediaId. Calling setMediaItem in that case would reset the
+                // player and discard the buffer — exactly what the warm pool exists to avoid.
+                // We still re-prepare if the player ended up IDLE somehow (e.g. it was demoted
+                // to cold and resurfaced, or hit an error before we attached).
+                val targetMediaId = mediaItem.item.mediaId
+                val needsLoad = state.controller.currentMediaItem?.mediaId != targetMediaId
+                if (needsLoad) {
+                    state.controller.setMediaItem(mediaItem.item)
+                    state.controller.prepare()
+                } else if (state.controller.playbackState == Player.STATE_IDLE) {
+                    Log.d("PlaybackService") { "Warm controller in STATE_IDLE — re-preparing" }
+                    state.controller.prepare()
+                }
             }
-    }.collectAsStateWithLifecycle(null)
+    }.collectAsState(null)
 
     controllerState?.let {
         inner(it)

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/LoadThumbAndThenVideoView.kt

@@ -29,7 +29,14 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.layout.ContentScale
 import androidx.compose.ui.platform.LocalContext
+import coil3.asDrawable
+import coil3.imageLoader
+import coil3.request.ImageRequest
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
+import com.vitorpamplona.quartz.utils.Log
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import kotlin.coroutines.cancellation.CancellationException
 
 @Composable
 fun LoadThumbAndThenVideoView(
@@ -45,56 +52,47 @@ fun LoadThumbAndThenVideoView(
     accountViewModel: AccountViewModel,
     onDialog: (() -> Unit)? = null,
 ) {
-    var loadingFinished by remember { mutableStateOf<Pair<Boolean, Drawable?>>(Pair(false, null)) }
+    var loadingFinished by remember(thumbUri) { mutableStateOf<Pair<Boolean, Drawable?>>(Pair(false, null)) }
     val context = LocalContext.current
 
-    LaunchedEffect(Unit) {
-        accountViewModel.loadThumb(
-            context,
-            thumbUri,
-            onReady = {
-                loadingFinished =
-                    if (it != null) {
-                        Pair(true, it)
-                    } else {
-                        Pair(true, null)
+    // Run the Coil fetch in this LaunchedEffect's scope (was previously launched into the
+    // AccountViewModel's viewModelScope, which meant a scroll-away wouldn't cancel the in-flight
+    // image request — wasted bandwidth, plus the late callback wrote into a state that no
+    // longer mattered). Keying on thumbUri also makes the effect re-fire when a recycled slot
+    // gets a new audio track with a new cover instead of stalling on the stale Pair(true, ...).
+    LaunchedEffect(thumbUri) {
+        loadingFinished =
+            try {
+                val request = ImageRequest.Builder(context).data(thumbUri).build()
+                val drawable =
+                    withContext(Dispatchers.IO) {
+                        context.imageLoader
+                            .execute(request)
+                            .image
+                            ?.asDrawable(context.resources)
                     }
-            },
-            onError = { loadingFinished = Pair(true, null) },
-        )
+                Pair(true, drawable)
+            } catch (e: Exception) {
+                if (e is CancellationException) throw e
+                Log.e("VideoView", "Fail to load cover $thumbUri", e)
+                Pair(true, null)
+            }
     }
 
     if (loadingFinished.first) {
-        if (loadingFinished.second != null) {
-            VideoView(
-                videoUri = videoUri,
-                mimeType = mimeType,
-                title = title,
-                thumb = VideoThumb(loadingFinished.second),
-                roundedCorner = roundedCorner,
-                contentScale = contentScale,
-                artworkUri = thumbUri,
-                authorName = authorName,
-                nostrUriCallback = nostrUriCallback,
-                isLiveStream = isLiveStream,
-                accountViewModel = accountViewModel,
-                onDialog = onDialog,
-            )
-        } else {
-            VideoView(
-                videoUri = videoUri,
-                mimeType = mimeType,
-                title = title,
-                thumb = null,
-                roundedCorner = roundedCorner,
-                contentScale = contentScale,
-                artworkUri = thumbUri,
-                authorName = authorName,
-                nostrUriCallback = nostrUriCallback,
-                isLiveStream = isLiveStream,
-                accountViewModel = accountViewModel,
-                onDialog = onDialog,
-            )
-        }
+        VideoView(
+            videoUri = videoUri,
+            mimeType = mimeType,
+            title = title,
+            thumb = loadingFinished.second?.let { VideoThumb(it) },
+            roundedCorner = roundedCorner,
+            contentScale = contentScale,
+            artworkUri = thumbUri,
+            authorName = authorName,
+            nostrUriCallback = nostrUriCallback,
+            isLiveStream = isLiveStream,
+            accountViewModel = accountViewModel,
+            onDialog = onDialog,
+        )
     }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/MediaControllerState.kt

@@ -31,14 +31,13 @@ import kotlin.uuid.Uuid
 class MediaControllerState(
     // each composable has an ID.
     val id: String = Uuid.random().toString(),
-    // This is filled after the controller returns from this class
-    var controller: Player,
+    val controller: Player,
     // visibility onscreen
     val visibility: VisibilityData = VisibilityData(),
 ) {
     fun isPlaying() = controller.isPlaying
 
-    fun currrentMedia() = controller.currentMediaItem?.mediaId
+    fun currentMedia() = controller.currentMediaItem?.mediaId
 
     fun toggleMute() {
         controller.volume = if (controller.volume == 0f) 1f else 0f

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/RenderVideoPlayer.kt

@@ -34,7 +34,6 @@ import androidx.compose.ui.geometry.Size
 import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.ui.layout.ContentScale
 import androidx.compose.ui.layout.onSizeChanged
-import androidx.compose.ui.unit.IntSize
 import androidx.media3.common.Player
 import androidx.media3.common.util.UnstableApi
 import androidx.media3.ui.compose.ContentFrame
@@ -90,19 +89,22 @@ fun RenderVideoPlayer(
     hasBlurhash: Boolean = false,
     accountViewModel: AccountViewModel,
 ) {
-    val containerSize = remember { mutableStateOf(IntSize.Zero) }
-    val isLive = isLiveStreaming(mediaItem.src.videoUri)
+    // Hold the container size in a non-state holder so layout passes don't trigger an
+    // unnecessary recomposition of the whole player tree just to update a value that is only
+    // ever read inside the onDoubleTap callback below.
+    val containerWidth = remember { intArrayOf(0) }
+    val isLive = remember(mediaItem.src.videoUri) { isLiveStreaming(mediaItem.src.videoUri) }
 
     Box(
         modifier =
             borderModifier
-                .onSizeChanged { containerSize.value = it }
+                .onSizeChanged { containerWidth[0] = it.width }
                 .pointerInput(isLive, controllerState) {
                     detectTapGestures(
                         onTap = { controllerVisible.value = !controllerVisible.value },
                         onDoubleTap = { offset ->
                             if (!isLive) {
-                                val isLeftSide = offset.x < containerSize.value.width / 2
+                                val isLeftSide = offset.x < containerWidth[0] / 2
                                 if (isLeftSide) {
                                     controllerState.controller.seekBackward()
                                 } else {

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/VideoView.kt

@@ -105,15 +105,32 @@ fun VideoView(
     thumbhash: String? = null,
 ) {
     val initialAutoStart = if (alwaysShowVideo) true else accountViewModel.settings.startVideoPlayback()
-    val automaticallyStartPlayback = remember { mutableStateOf(initialAutoStart) }
+    // Reset the manual-show toggle when the video URI changes so a recycled feed slot
+    // doesn't inherit "tapped to show" state from a prior video.
+    val automaticallyStartPlayback = remember(videoUri) { mutableStateOf(initialAutoStart) }
 
     // Once the video is being shown, only honor the user's autoplay preference when it was auto-loaded.
     // If the user manually tapped the download button, they want it to play.
     val autoplay = alwaysShowVideo || (initialAutoStart && accountViewModel.settings.autoPlayVideos()) || (!initialAutoStart && automaticallyStartPlayback.value)
 
-    if (blurhash == null && thumbhash == null) {
-        val ratio = dimensions?.aspectRatio() ?: MediaAspectRatioCache.get(videoUri)
+    // Resolve the aspect ratio once per composition. Prime the URL-keyed cache from the imeta
+    // dim tag so the next time this video appears (PiP, dialog, list re-enter) the cache hits
+    // without waiting for ExoPlayer's onVideoSizeChanged. Keys are primitive width/height so
+    // a freshly parsed DimensionTag instance for the same event doesn't re-run this lambda —
+    // DimensionTag uses reference equality, not structural.
+    val dimW = dimensions?.width
+    val dimH = dimensions?.height
+    val ratio =
+        remember(videoUri, dimW, dimH) {
+            if (dimW != null && dimH != null && dimW > 0 && dimH > 0) {
+                MediaAspectRatioCache.add(videoUri, dimW, dimH)
+                dimW.toFloat() / dimH.toFloat()
+            } else {
+                MediaAspectRatioCache.get(videoUri)
+            }
+        }
 
+    if (blurhash == null && thumbhash == null) {
         val modifier =
             if (ratio != null && automaticallyStartPlayback.value) {
                 Modifier.aspectRatio(ratio)
@@ -149,8 +166,6 @@ fun VideoView(
             }
         }
     } else {
-        val ratio = dimensions?.aspectRatio() ?: MediaAspectRatioCache.get(videoUri)
-
         val modifier =
             if (ratio != null) {
                 Modifier.aspectRatio(ratio)

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/VideoViewInner.kt

@@ -59,6 +59,11 @@ fun VideoViewInner(
     // keeps a copy of the value to avoid recompositions here when the DEFAULT value changes
     val muted = remember(videoUri) { DEFAULT_MUTED_SETTING.value }
 
+    // The proxy port is decided once per video URI; recomputing on every recomposition does
+    // pointless work (the result is anyway dropped because GetMediaItem.remember is keyed on the
+    // URI alone, so the cached MediaItemData is locked in on the first frame).
+    val proxyPort = remember(videoUri) { accountViewModel.httpClientBuilder.proxyPortForVideo(videoUri) }
+
     GetMediaItem(
         videoUri = videoUri,
         title = title,
@@ -67,7 +72,7 @@ fun VideoViewInner(
         callbackUri = nostrUriCallback,
         mimeType = mimeType,
         aspectRatio = aspectRatio,
-        proxyPort = accountViewModel.httpClientBuilder.proxyPortForVideo(videoUri),
+        proxyPort = proxyPort,
         keepPlaying = true,
         waveformData = waveform,
         isLiveStream = isLiveStream,

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/controls/GradientOverlay.kt

@@ -38,24 +38,33 @@ import androidx.compose.ui.unit.dp
 private val FadeIn = fadeIn()
 private val FadeOut = fadeOut()
 
-private val TopGradientColors =
-    listOf(
-        Color.Black.copy(alpha = 0.6f),
-        Color.Black.copy(alpha = 0.3f),
-        Color.Transparent,
+// Both gradient brushes are static; pre-build them once at class init so we don't allocate a
+// new Brush on every recomposition while the controllers are visible (which is most of the
+// time during playback / interaction).
+private val TopGradientBrush =
+    Brush.verticalGradient(
+        colors =
+            listOf(
+                Color.Black.copy(alpha = 0.6f),
+                Color.Black.copy(alpha = 0.3f),
+                Color.Transparent,
+            ),
     )
 
-private val BottomGradientColors =
-    listOf(
-        Color.Transparent,
-        Color.Black.copy(alpha = 0.4f),
-        Color.Black.copy(alpha = 0.7f),
+private val BottomGradientBrush =
+    Brush.verticalGradient(
+        colors =
+            listOf(
+                Color.Transparent,
+                Color.Black.copy(alpha = 0.4f),
+                Color.Black.copy(alpha = 0.7f),
+            ),
     )
 
 @Composable
 private fun GradientOverlay(
     controllerVisible: State<Boolean>,
-    colors: List<Color>,
+    brush: Brush,
     height: Dp,
     modifier: Modifier = Modifier,
 ) {
@@ -70,7 +79,7 @@ private fun GradientOverlay(
                 Modifier
                     .fillMaxWidth()
                     .height(height)
-                    .background(brush = Brush.verticalGradient(colors = colors)),
+                    .background(brush = brush),
         )
     }
 }
@@ -80,11 +89,11 @@ fun TopGradientOverlay(
     controllerVisible: State<Boolean>,
     modifier: Modifier = Modifier,
     height: Dp = 80.dp,
-) = GradientOverlay(controllerVisible, TopGradientColors, height, modifier)
+) = GradientOverlay(controllerVisible, TopGradientBrush, height, modifier)
 
 @Composable
 fun BottomGradientOverlay(
     controllerVisible: State<Boolean>,
     modifier: Modifier = Modifier,
     height: Dp = 120.dp,
-) = GradientOverlay(controllerVisible, BottomGradientColors, height, modifier)
+) = GradientOverlay(controllerVisible, BottomGradientBrush, height, modifier)

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/controls/MuteButton.kt

@@ -47,9 +47,7 @@ import com.vitorpamplona.amethyst.ui.theme.Size30Modifier
 import com.vitorpamplona.amethyst.ui.theme.Size50Modifier
 import com.vitorpamplona.amethyst.ui.theme.ThemeComparisonColumn
 import com.vitorpamplona.amethyst.ui.theme.VolumeBottomIconSize
-import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.delay
-import kotlinx.coroutines.launch
 
 @Preview
 @Composable
@@ -79,11 +77,12 @@ fun MuteButton(
             )
         }
 
+    // LaunchedEffect already runs on Main, and delay() suspends without holding a thread, so
+    // the previous launch(Dispatchers.IO) was just unnecessary dispatcher hopping for a state
+    // mutation that's also fine on Main.
     LaunchedEffect(key1 = controllerVisible) {
-        launch(Dispatchers.IO) {
-            delay(2000)
-            holdOn.value = false
-        }
+        delay(2000)
+        holdOn.value = false
     }
 
     val mutedInstance = remember(startingMuteState) { mutableStateOf(startingMuteState) }

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/controls/OverflowMenu.kt

@@ -50,6 +50,8 @@ import com.vitorpamplona.amethyst.ui.theme.Size20Modifier
 import com.vitorpamplona.amethyst.ui.theme.Size50Modifier
 import com.vitorpamplona.amethyst.ui.theme.ThemeComparisonColumn
 import com.vitorpamplona.amethyst.ui.theme.VolumeBottomIconSize
+import kotlinx.collections.immutable.ImmutableList
+import kotlinx.collections.immutable.persistentListOf
 
 private val FadeIn = fadeIn()
 private val FadeOut = fadeOut()
@@ -60,7 +62,7 @@ fun OverflowMenuButtonPreview() {
     ThemeComparisonColumn {
         Box(Modifier.background(BitcoinOrange)) {
             OverflowMenuButton(
-                actions = listOf(VideoPlayerAction.Share, VideoPlayerAction.Download, VideoPlayerAction.PictureInPicture),
+                actions = persistentListOf(VideoPlayerAction.Share, VideoPlayerAction.Download, VideoPlayerAction.PictureInPicture),
                 startingMuteState = false,
                 onFullscreenClick = {},
                 onMuteClick = {},
@@ -76,7 +78,7 @@ fun OverflowMenuButtonPreview() {
 @Composable
 fun AnimatedOverflowMenuButton(
     controllerVisible: State<Boolean>,
-    actions: List<VideoPlayerAction>,
+    actions: ImmutableList<VideoPlayerAction>,
     startingMuteState: Boolean,
     onFullscreenClick: (() -> Unit)?,
     onMuteClick: () -> Unit,
@@ -107,7 +109,7 @@ fun AnimatedOverflowMenuButton(
 
 @Composable
 fun OverflowMenuButton(
-    actions: List<VideoPlayerAction>,
+    actions: ImmutableList<VideoPlayerAction>,
     startingMuteState: Boolean,
     onFullscreenClick: (() -> Unit)?,
     onMuteClick: () -> Unit,

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/controls/RenderTopButtons.kt

@@ -70,6 +70,7 @@ import com.vitorpamplona.amethyst.ui.theme.PinBottomIconSize
 import com.vitorpamplona.amethyst.ui.theme.Size20Modifier
 import com.vitorpamplona.amethyst.ui.theme.Size50Modifier
 import com.vitorpamplona.amethyst.ui.theme.ThemeComparisonColumn
+import kotlinx.collections.immutable.toImmutableList
 
 @Preview
 @Composable
@@ -105,7 +106,7 @@ fun RenderTopButtons(
     accountViewModel: AccountViewModel,
 ) {
     val context = LocalContext.current
-    val isLive = isLiveStreaming(mediaData.videoUri)
+    val isLive = remember(mediaData.videoUri) { isLiveStreaming(mediaData.videoUri) }
     val pipSupported =
         remember {
             context.packageManager.hasSystemFeature(PackageManager.FEATURE_PICTURE_IN_PICTURE)
@@ -212,17 +213,22 @@ fun RenderTopButtons(
         }
 
     val canFullscreen = onZoomClick != null
+    // ImmutableList so Compose can treat the action lists as stable parameters when they're
+    // passed through to AnimatedOverflowMenuButton — a plain List is unstable and forces the
+    // overflow tree to recompose whenever any unrelated parent state ticks.
     val topBarActions =
         remember(buttonItems, canFullscreen, hasMultipleQualities, isLive, pipSupported) {
             buttonItems
                 .filter { it.location == VideoButtonLocation.TopBar && isAvailable(it.action) }
                 .map { it.action }
+                .toImmutableList()
         }
     val overflowActions =
         remember(buttonItems, canFullscreen, hasMultipleQualities, isLive, pipSupported) {
             buttonItems
                 .filter { it.location == VideoButtonLocation.OverflowMenu && isAvailable(it.action) }
                 .map { it.action }
+                .toImmutableList()
         }
 
     Row(modifier) {

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/pip/PipVideoView.kt

@@ -58,7 +58,7 @@ fun RenderPipVideo(
     val modifier =
         remember {
             val ratio =
-                controller.currrentMedia()?.let {
+                controller.currentMedia()?.let {
                     MediaAspectRatioCache.get(it)
                 }
 

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/playerPool/ExoPlayerBuilder.kt

@@ -24,6 +24,7 @@ import android.content.Context
 import androidx.annotation.OptIn
 import androidx.media3.common.util.UnstableApi
 import androidx.media3.datasource.DataSource
+import androidx.media3.exoplayer.DefaultLoadControl
 import androidx.media3.exoplayer.ExoPlayer
 import com.vitorpamplona.amethyst.model.MediaAspectRatioCache
 import com.vitorpamplona.amethyst.service.playback.diskCache.VideoCache
@@ -42,10 +43,35 @@ class ExoPlayerBuilder(
             .Builder(context)
             .apply {
                 setMediaSourceFactory(CustomMediaSourceFactory(videoCache, dataSourceFactory))
+                setLoadControl(feedTunedLoadControl())
             }.build()
             .apply {
                 addListener(AspectRatioCacher(MediaAspectRatioCache))
                 addListener(KeepVideosPlaying(this))
                 addListener(CurrentPlayPositionCacher(this, VideoViewedPositionCache))
             }
+
+    companion object {
+        // Default DefaultLoadControl buffers 50s ahead before slowing down. Every visible video
+        // in the feed is prepared eagerly so it's ready when the user scrolls to it; with the
+        // default settings 5 simultaneous preloads would fight for ~250s of buffer between them
+        // and chew through ~30+ MB per HD player. Feed playback is optimized for "the active
+        // video plays smoothly while a few neighbours stay warm," so we cap the buffer at ~15s
+        // and let playback kick in as soon as ~750 ms is buffered. Fullscreen still gets a
+        // healthy buffer because seeks-within-15s are virtually instant from disk cache.
+        private fun feedTunedLoadControl() =
+            DefaultLoadControl
+                .Builder()
+                .setBufferDurationsMs(
+                    // minBufferMs =
+                    10_000,
+                    // maxBufferMs =
+                    15_000,
+                    // bufferForPlaybackMs =
+                    750,
+                    // bufferForPlaybackAfterRebufferMs =
+                    2_000,
+                ).setPrioritizeTimeOverSizeThresholds(true)
+                .build()
+    }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/playerPool/ExoPlayerPool.kt

@@ -34,16 +34,43 @@ import kotlinx.coroutines.cancel
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
+import kotlinx.coroutines.yield
 import java.util.concurrent.ConcurrentLinkedQueue
+import java.util.concurrent.atomic.AtomicBoolean
 
 @OptIn(UnstableApi::class)
 class ExoPlayerPool(
     val builder: ExoPlayerBuilder,
     private val poolSize: Int,
+    // Requested ceiling on paused-with-buffer players retained across releases. Each retained
+    // player keeps its decoder and LoadControl buffer alive, which costs both memory and a
+    // MediaCodec instance, so warm slots count against the same [poolSize] codec budget as
+    // cold players (see [warmSlotsCap]). Default 3 keeps the most recent few feed videos hot
+    // for scroll-back without monopolizing the device's decoder pool.
+    requestedWarmSlots: Int = DEFAULT_WARM_SLOTS,
 ) {
-    private val playerPool = ConcurrentLinkedQueue<ExoPlayer>()
+    // Cap warm slots at poolSize-1 so there's always at least one slot available for a cold
+    // (cleared) player; otherwise a feed full of unique URIs would starve the cold pool and
+    // every new URI would force a fresh ExoPlayer build.
+    private val warmSlotsCap = requestedWarmSlots.coerceAtMost((poolSize - 1).coerceAtLeast(0))
+
+    // Idle players that have been stop()'d and clearMediaItems()'d — ready to be re-prepared
+    // with any URI. Maintained as a FIFO so the oldest cleared instance is reused first.
+    private val coldPool = ConcurrentLinkedQueue<ExoPlayer>()
     private val poolStartingSize = 3
 
+    // Most-recent paused players, indexed by the mediaId of the MediaItem they still hold.
+    // ArrayDeque is used as an LRU: head = oldest, tail = newest. Access is guarded by
+    // [warmPoolLock] (a plain monitor, since both acquire and release callers run on the
+    // service's main thread but we don't want to require the suspending [mutex] in acquire).
+    private data class WarmPlayer(
+        val mediaId: String,
+        val player: ExoPlayer,
+    )
+
+    private val warmPool = ArrayDeque<WarmPlayer>(warmSlotsCap.coerceAtLeast(1))
+    private val warmPoolLock = Any()
+
     // Exists to avoid exceptions stopping the coroutine
     val exceptionHandler =
         CoroutineExceptionHandler { _, throwable ->
@@ -54,21 +81,63 @@ class ExoPlayerPool(
 
     private val mutex = Mutex()
 
+    // Guards against firing the warmup more than once if create() is called repeatedly
+    // (e.g. on reconfiguration or when both pools share a startup hook).
+    private val warmupStarted = AtomicBoolean(false)
+
+    /**
+     * Pre-warms the pool with [poolStartingSize] ExoPlayer instances on the main looper, yielding
+     * between each build so the warmup is spread across frames instead of stalling the UI in one
+     * burst. ExoPlayer must be constructed on the same thread that will operate it (the main
+     * thread for this pool), so we cannot fan out across IO threads here. Idempotent — additional
+     * calls are no-ops.
+     */
     fun create(context: Context) {
-        while (playerPool.size < poolStartingSize) {
-            playerPool.offer(builder.build(context))
+        if (!warmupStarted.compareAndSet(false, true)) return
+        scope.launch {
+            while (coldPool.size < poolStartingSize) {
+                coldPool.offer(builder.build(context))
+                // Hand the frame back so an in-flight onGetSession / acquirePlayer / layout
+                // pass isn't blocked behind the next build.
+                yield()
+            }
         }
     }
 
-    fun acquirePlayer(context: Context): ExoPlayer {
-        if (playerPool.isEmpty()) {
-            // If the pool is empty, create a new player (or handle it differently)
-            return builder.build(context)
+    /**
+     * Acquire a player. When [preferredMediaId] matches a warm entry, returns that player intact
+     * — it still holds its MediaItem and any populated LoadControl buffer, so the caller can
+     * skip [androidx.media3.common.Player.setMediaItem] / [androidx.media3.common.Player.prepare]
+     * and resume immediately. Falls back to a cold (cleared) player or a freshly built one.
+     */
+    fun acquirePlayer(
+        context: Context,
+        preferredMediaId: String? = null,
+    ): ExoPlayer {
+        if (preferredMediaId != null) {
+            val warm = takeWarm(preferredMediaId)
+            if (warm != null) {
+                Log.d("PlaybackService") { "ExoPlayerPool warm hit: $preferredMediaId" }
+                return warm
+            }
         }
-
-        return playerPool.poll() ?: builder.build(context)
+        return coldPool.poll() ?: builder.build(context)
     }
 
+    private fun takeWarm(mediaId: String): ExoPlayer? =
+        synchronized(warmPoolLock) {
+            // Iterate from the newest end so a duplicated URI returns the freshest player.
+            val it = warmPool.listIterator(warmPool.size)
+            while (it.hasPrevious()) {
+                val entry = it.previous()
+                if (entry.mediaId == mediaId) {
+                    it.remove()
+                    return@synchronized entry.player
+                }
+            }
+            null
+        }
+
     fun releasePlayerAsync(player: ExoPlayer) {
         scope.launch {
             releasePlayer(player)
@@ -77,27 +146,70 @@ class ExoPlayerPool(
 
     suspend fun releasePlayer(player: ExoPlayer) {
         mutex.withLock {
-            if (!player.isReleased) {
+            if (player.isReleased) return@withLock
+
+            val mediaId = player.currentMediaItem?.mediaId
+            if (mediaId != null && warmSlotsCap > 0) {
+                // Warm path: keep the player paused but loaded so a quick scroll-back to the
+                // same video resumes from the existing buffer instead of re-fetching from disk
+                // cache and re-priming the decoder.
                 player.pause()
-                player.stop()
-                player.clearVideoSurface()
-                player.clearMediaItems()
-
-                // Clear any video quality overrides so the next video starts with Auto
-                player.trackSelectionParameters =
-                    player.trackSelectionParameters
-                        .buildUpon()
-                        .clearOverridesOfType(C.TRACK_TYPE_VIDEO)
-                        .build()
-
-                if (playerPool.size < poolSize) {
-                    if (!playerPool.contains(player)) {
-                        playerPool.add(player)
-                    }
-                } else {
-                    player.release() // Release if pool is full.
+                val evicted = pushWarm(mediaId, player)
+                if (evicted != null) {
+                    Log.d("PlaybackService") { "ExoPlayerPool warm evict: ${evicted.mediaId}" }
+                    demoteToCold(evicted.player)
                 }
+                return@withLock
             }
+
+            demoteToCold(player)
+        }
+    }
+
+    private fun pushWarm(
+        mediaId: String,
+        player: ExoPlayer,
+    ): WarmPlayer? =
+        synchronized(warmPoolLock) {
+            // If the same URI is already warm (rare — duplicate VideoView in another scroller),
+            // drop the older entry so it can be demoted; the freshest copy wins.
+            val duplicate = warmPool.indexOfFirst { it.mediaId == mediaId }
+            val displaced =
+                if (duplicate >= 0) {
+                    warmPool.removeAt(duplicate)
+                } else if (warmPool.size >= warmSlotsCap) {
+                    warmPool.removeFirst()
+                } else {
+                    null
+                }
+            warmPool.addLast(WarmPlayer(mediaId, player))
+            displaced
+        }
+
+    private fun demoteToCold(player: ExoPlayer) {
+        if (player.isReleased) return
+        player.pause()
+        player.stop()
+        player.clearVideoSurface()
+        player.clearMediaItems()
+
+        // Clear any video quality overrides so the next video starts with Auto
+        player.trackSelectionParameters =
+            player.trackSelectionParameters
+                .buildUpon()
+                .clearOverridesOfType(C.TRACK_TYPE_VIDEO)
+                .build()
+
+        // Total idle (cold + warm) must respect the device-derived poolSize cap so we don't
+        // exceed the MediaCodec instance budget. Warm slots get first dibs; cold gets the rest.
+        val warmSize = synchronized(warmPoolLock) { warmPool.size }
+        val coldCap = (poolSize - warmSize).coerceAtLeast(0)
+        if (coldPool.size < coldCap) {
+            if (!coldPool.contains(player)) {
+                coldPool.add(player)
+            }
+        } else {
+            player.release() // Release if pool is full.
         }
     }
 
@@ -105,11 +217,22 @@ class ExoPlayerPool(
         scope
             .launch {
                 mutex.withLock {
-                    playerPool.forEach { it.release() }
-                    playerPool.clear()
+                    val warmSnapshot =
+                        synchronized(warmPoolLock) {
+                            val copy = warmPool.toList()
+                            warmPool.clear()
+                            copy
+                        }
+                    warmSnapshot.forEach { it.player.release() }
+                    coldPool.forEach { it.release() }
+                    coldPool.clear()
                 }
             }.invokeOnCompletion {
                 scope.cancel()
             }
     }
+
+    companion object {
+        private const val DEFAULT_WARM_SLOTS = 3
+    }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/playerPool/MediaSessionPool.kt

@@ -37,13 +37,14 @@ import com.google.common.util.concurrent.Futures
 import com.google.common.util.concurrent.ListenableFuture
 import com.vitorpamplona.amethyst.service.playback.composable.mediaitem.MediaItemCache
 import com.vitorpamplona.amethyst.ui.MainActivity
-import com.vitorpamplona.quartz.utils.TimeUtils
 import kotlinx.coroutines.CoroutineExceptionHandler
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.SupervisorJob
 import kotlinx.coroutines.cancel
 import kotlinx.coroutines.launch
+import java.util.concurrent.TimeUnit
+import java.util.concurrent.atomic.AtomicLong
 
 class SessionListener(
     val session: MediaSession,
@@ -72,7 +73,22 @@ class MediaSessionPool(
     private val scope = CoroutineScope(SupervisorJob() + Dispatchers.Main + exceptionHandler)
 
     val globalCallback = MediaSessionCallback(this, appContext)
-    var lastCleanup = TimeUtils.now()
+
+    // Last cleanup timestamp in nanos, guarded by CAS so concurrent releaseSession() calls
+    // can't all win the time check and each launch a redundant scope.launch sweep.
+    private val lastCleanupNs = AtomicLong(System.nanoTime())
+
+    // The bitmap loader is stateless w.r.t. the session; a fresh allocation per session was
+    // pure noise. ExoPlayer's DEFAULT_EXECUTOR_SERVICE is a process-wide singleton, the
+    // dataSourceFactory is owned by the pool, and the appContext is already retained.
+    @OptIn(UnstableApi::class)
+    private val sharedBitmapLoader by lazy {
+        DataSourceBitmapLoader
+            .Builder(appContext)
+            .setExecutorService(DataSourceBitmapLoader.DEFAULT_EXECUTOR_SERVICE.get())
+            .setDataSourceFactory(dataSourceFactory)
+            .build()
+    }
 
     // protects from LruCache killing playing sessions
     private val playingMap = mutableMapOf<String, SessionListener>()
@@ -102,18 +118,16 @@ class MediaSessionPool(
         id: String,
         keepPlaying: Boolean,
         context: Context,
+        // Best-effort affinity hint: when the pool still has a paused player carrying this
+        // exact mediaId (matches MediaItem.mediaId, which is the videoUri), the warm player
+        // is reused so the populated buffer survives. Null falls back to a cold acquire.
+        preferredMediaId: String?,
     ): MediaSession {
         val mediaSession =
             MediaSession
-                .Builder(context, exoPlayerPool.acquirePlayer(context))
+                .Builder(context, exoPlayerPool.acquirePlayer(context, preferredMediaId))
                 .apply {
-                    setBitmapLoader(
-                        DataSourceBitmapLoader
-                            .Builder(context)
-                            .setExecutorService(DataSourceBitmapLoader.DEFAULT_EXECUTOR_SERVICE.get())
-                            .setDataSourceFactory(dataSourceFactory)
-                            .build(),
-                    )
+                    setBitmapLoader(sharedBitmapLoader)
                     setId(id)
                     setCallback(globalCallback)
                 }.build()
@@ -142,16 +156,17 @@ class MediaSessionPool(
     }
 
     fun cleanupUnused() {
-        if (lastCleanup < TimeUtils.oneMinuteAgo()) {
-            lastCleanup = TimeUtils.now()
-            scope.launch {
-                val snap = cache.snapshot()
-                snap.values.forEach {
-                    if (it.session.connectedControllers.isEmpty()) {
-                        releaseSession(it.session)
-                    }
+        val now = System.nanoTime()
+        val previous = lastCleanupNs.get()
+        if (now - previous < CLEANUP_INTERVAL_NS) return
+        // CAS so only one caller actually launches the sweep when many releases fire at once.
+        if (!lastCleanupNs.compareAndSet(previous, now)) return
+        scope.launch {
+            val snap = cache.snapshot()
+            snap.values.forEach {
+                if (it.session.connectedControllers.isEmpty()) {
+                    releaseSession(it.session)
                 }
-                lastCleanup = TimeUtils.now()
             }
         }
     }
@@ -175,13 +190,14 @@ class MediaSessionPool(
         id: String,
         keepPlaying: Boolean,
         context: Context,
+        preferredMediaId: String? = null,
     ): MediaSession {
         val existingSession = playingMap.get(id) ?: cache.get(id)
         if (existingSession != null) {
             return existingSession.session
         }
 
-        return newSession(id, keepPlaying, context)
+        return newSession(id, keepPlaying, context, preferredMediaId)
     }
 
     fun playingContent() = playingMap.values
@@ -234,4 +250,8 @@ class MediaSessionPool(
             }
         }
     }
+
+    companion object {
+        private val CLEANUP_INTERVAL_NS = TimeUnit.MINUTES.toNanos(1)
+    }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/playerPool/positions/CurrentPlayPositionCacher.kt

@@ -66,7 +66,14 @@ class CurrentPlayPositionCacher(
                 Player.STATE_READY -> {
                     if (!isLiveStreaming) {
                         cache.get(uri)?.let { lastPosition ->
-                            if (abs(player.currentPosition - lastPosition) > 5 * 60) {
+                            // Restore the saved position only if it's meaningfully far from
+                            // the player's current position. Position values are in
+                            // milliseconds, so the previous `5 * 60` constant was a 300 ms
+                            // threshold — small enough to trigger a seek (and an extra buffer
+                            // flush right at playback start) for almost any saved position.
+                            // 5 s gives the user a perceptible "resumed where I left off"
+                            // without forcing a re-seek for trivially short clips.
+                            if (abs(player.currentPosition - lastPosition) > 5_000) {
                                 player.seekTo(lastPosition)
                             }
                         }

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/service/PlaybackService.kt

@@ -105,7 +105,15 @@ class PlaybackService : MediaSessionService() {
             val blossomServerResolver = Amethyst.instance.blossomResolver
 
             // creates new
-            return newPool(videoCache, okHttpClient, blossomServerResolver).also { poolNoProxy = it }
+            return newPool(videoCache, okHttpClient, blossomServerResolver)
+                .also {
+                    poolNoProxy = it
+                    // Kick off the player pool warmup as soon as we know this pool is being used.
+                    // It runs async on the main looper, yielding between builds, so the very first
+                    // session still acquires synchronously while subsequent ones can grab a warm
+                    // ExoPlayer instead of paying the build cost on the main thread.
+                    it.exoPlayerPool.create(applicationContext)
+                }
         } else {
             poolWithProxy?.let { return it }
 
@@ -116,7 +124,11 @@ class PlaybackService : MediaSessionService() {
             val videoCache = Amethyst.instance.videoCache
             val blossomServerResolver = Amethyst.instance.blossomResolver
 
-            return newPool(videoCache, okHttpClient, blossomServerResolver).also { poolWithProxy = it }
+            return newPool(videoCache, okHttpClient, blossomServerResolver)
+                .also {
+                    poolWithProxy = it
+                    it.exoPlayerPool.create(applicationContext)
+                }
         }
     }
 
@@ -161,23 +173,27 @@ class PlaybackService : MediaSessionService() {
             return
         }
 
-        playing.forEachIndexed { idx, it ->
+        playing.forEach {
             if (it.session.player.isPlaying && it.session.player.volume > 0 && it.session.id == BackgroundMedia.bgInstance?.id) {
                 super.onUpdateNotification(it.session, startInForegroundRequired)
                 return
             }
         }
 
-        playing.forEachIndexed { idx, it ->
+        playing.forEach {
             if (it.session.player.isPlaying && it.session.player.volume > 0) {
                 super.onUpdateNotification(it.session, startInForegroundRequired)
                 return
             }
         }
 
-        playing.forEachIndexed { idx, it ->
+        // Falls through to the first muted-but-playing session. Earlier this loop missed
+        // its return and called super.onUpdateNotification once per playing session,
+        // hammering the notification system whenever multiple feed videos were preloading.
+        playing.forEach {
             if (it.session.player.isPlaying) {
                 super.onUpdateNotification(it.session, startInForegroundRequired)
+                return
             }
         }
     }
@@ -188,7 +204,17 @@ class PlaybackService : MediaSessionService() {
         val id = controllerInfo.connectionHints.getString("id") ?: return null
         val proxyPort = controllerInfo.connectionHints.getInt("proxyPort")
         val keepPlaying = controllerInfo.connectionHints.getBoolean("keepPlaying", true)
+        // Optional warm-pool affinity hint: when the pool still has a paused ExoPlayer
+        // holding this exact URI, the new session reuses it so the buffer survives.
+        val preferredMediaId = controllerInfo.connectionHints.getString(HINT_VIDEO_URI)
         val manager = lazyPool(proxyPort)
-        return manager.getSession(id, keepPlaying, applicationContext)
+        return manager.getSession(id, keepPlaying, applicationContext, preferredMediaId)
+    }
+
+    companion object {
+        const val HINT_ID = "id"
+        const val HINT_PROXY_PORT = "proxyPort"
+        const val HINT_KEEP_PLAYING = "keepPlaying"
+        const val HINT_VIDEO_URI = "videoUri"
     }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/service/PlaybackServiceClient.kt

@@ -36,7 +36,15 @@ import kotlin.uuid.ExperimentalUuidApi
 import kotlin.uuid.Uuid
 
 object PlaybackServiceClient {
-    val executorService: ExecutorService = Executors.newCachedThreadPool()
+    // Runs the MediaController.buildAsync() completion callbacks. The work per callback is
+    // trivial in the steady state (Future.get() on an already-completed future + a non-blocking
+    // trySend into this video's own callbackFlow channel), so the IPC bind itself dominates and
+    // happens on Media3's own threads regardless. We size the pool small enough to stay bounded
+    // under churn but parallel enough that one stuck listener (e.g. the defensive 5s get()
+    // timeout actually firing) can't stall the rest of the videos onscreen behind it. The
+    // original newCachedThreadPool was unbounded and could spin up a thread per concurrent
+    // video, each lingering for the 60s keep-alive afterwards.
+    val executorService: ExecutorService = Executors.newFixedThreadPool(4)
 
     fun shutdown() {
         executorService.shutdown()
@@ -56,11 +64,15 @@ object PlaybackServiceClient {
             Bundle().apply {
                 // link the id with the client's id to make sure it can return the
                 // same session on background media.
-                putString("id", id)
-                putBoolean("keepPlaying", keepPlaying)
+                putString(PlaybackService.HINT_ID, id)
+                putBoolean(PlaybackService.HINT_KEEP_PLAYING, keepPlaying)
                 proxyPort?.let {
-                    putInt("proxyPort", it)
+                    putInt(PlaybackService.HINT_PROXY_PORT, it)
                 }
+                // Carry the URI so the service can ask the player pool for an existing warm
+                // (paused-with-buffer) ExoPlayer that already holds this MediaItem. Falls back
+                // gracefully — if no warm match exists, the pool returns a cold player.
+                putString(PlaybackService.HINT_VIDEO_URI, videoUri)
             }
 
         val session = SessionToken(appContext, ComponentName(appContext, PlaybackService::class.java))

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/components/GifVideoView.kt

@@ -68,6 +68,10 @@ fun GifVideoView(
     accountViewModel: AccountViewModel,
     thumbhash: String? = null,
 ) {
+    // Pure read path — DimensionTag.aspectRatio() is a one-line int division and
+    // MediaAspectRatioCache.get() is a synchronized LruCache lookup. Wrapping this in
+    // remember() to avoid the recompute would cost more (slot read + N equality checks)
+    // than the work it saves; that's why this stays as a plain expression.
     val ratio = dimensions?.aspectRatio() ?: MediaAspectRatioCache.get(videoUri)
     val autoPlay = accountViewModel.settings.autoPlayVideos()
     val borderModifier = if (roundedCorner) MaterialTheme.colorScheme.imageModifier else Modifier

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/AccountViewModel.kt

@@ -22,7 +22,6 @@ package com.vitorpamplona.amethyst.ui.screen.loggedIn
 
 import android.annotation.SuppressLint
 import android.content.Context
-import android.graphics.drawable.Drawable
 import android.os.Handler
 import android.os.Looper
 import android.util.LruCache
@@ -34,9 +33,6 @@ import androidx.compose.runtime.rememberCoroutineScope
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
 import androidx.lifecycle.viewModelScope
-import coil3.asDrawable
-import coil3.imageLoader
-import coil3.request.ImageRequest
 import com.vitorpamplona.amethyst.AccountInfo
 import com.vitorpamplona.amethyst.Amethyst
 import com.vitorpamplona.amethyst.LocalPreferences
@@ -1578,29 +1574,6 @@ class AccountViewModel(
         super.onCleared()
     }
 
-    fun loadThumb(
-        context: Context,
-        thumbUri: String,
-        onReady: (Drawable?) -> Unit,
-        onError: (String?) -> Unit,
-    ) {
-        viewModelScope.launch(Dispatchers.IO) {
-            try {
-                val request = ImageRequest.Builder(context).data(thumbUri).build()
-                val myCover =
-                    context.imageLoader
-                        .execute(request)
-                        .image
-                        ?.asDrawable(context.resources)
-                onReady(myCover)
-            } catch (e: Exception) {
-                if (e is CancellationException) throw e
-                Log.e("VideoView", "Fail to load cover $thumbUri", e)
-                onError(e.message)
-            }
-        }
-    }
-
     fun loadMentions(
         mentions: ImmutableList<String>,
         onReady: (ImmutableList<User>) -> Unit,