From 36277076bd846e768f0e4bb7655159d4cde1b6d9 Mon Sep 17 00:00:00 2001
From: edde746 <86283021+edde746@users.noreply.github.com>
Date: Mon, 2 Mar 2026 02:30:48 +0100
Subject: [PATCH] fix(android): cap demuxer buffers + sync mpv dispose

---
 .../com/edde746/plezy/mpv/MpvPlayerCore.kt    | 14 +++++++++--
 .../com/edde746/plezy/mpv/MpvPlayerPlugin.kt  | 12 ++++++----
 lib/screens/video_player_screen.dart          | 24 +++++++++++++++++++
 3 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/android/app/src/main/kotlin/com/edde746/plezy/mpv/MpvPlayerCore.kt b/android/app/src/main/kotlin/com/edde746/plezy/mpv/MpvPlayerCore.kt
index 462c6bf9..c1bc8c58 100644
--- a/android/app/src/main/kotlin/com/edde746/plezy/mpv/MpvPlayerCore.kt
+++ b/android/app/src/main/kotlin/com/edde746/plezy/mpv/MpvPlayerCore.kt
@@ -471,8 +471,11 @@ class MpvPlayerCore(private val activity: Activity) :
 
     // Cleanup
 
-    fun dispose() {
-        if (disposing) return
+    fun dispose(onComplete: (() -> Unit)? = null) {
+        if (disposing) {
+            onComplete?.invoke()
+            return
+        }
         disposing = true
         Log.d(TAG, "Disposing")
 
@@ -519,6 +522,10 @@ class MpvPlayerCore(private val activity: Activity) :
         // Run native destroy on background thread to avoid ANR —
         // MPVLib.destroy() blocks on pthread_cond_wait while mpv's
         // internal threads (lua, demux, vo) shut down.
+        // The completion callback is posted to the main thread so the
+        // caller (MpvPlayerPlugin) can defer result.success() until
+        // native resources are fully released, preventing a new mpv
+        // instance from being created while the old one still holds memory.
         if (nativeReady) {
             Thread {
                 synchronized(mpvLock) {
@@ -531,7 +538,10 @@ class MpvPlayerCore(private val activity: Activity) :
                     }
                 }
                 Log.d(TAG, "Disposed (native)")
+                onComplete?.let { Handler(Looper.getMainLooper()).post(it) }
             }.start()
+        } else {
+            onComplete?.invoke()
         }
     }
 }
diff --git a/android/app/src/main/kotlin/com/edde746/plezy/mpv/MpvPlayerPlugin.kt b/android/app/src/main/kotlin/com/edde746/plezy/mpv/MpvPlayerPlugin.kt
index 37eacdac..29a0f2fc 100644
--- a/android/app/src/main/kotlin/com/edde746/plezy/mpv/MpvPlayerPlugin.kt
+++ b/android/app/src/main/kotlin/com/edde746/plezy/mpv/MpvPlayerPlugin.kt
@@ -142,10 +142,14 @@ class MpvPlayerPlugin : FlutterPlugin, MethodChannel.MethodCallHandler,
 
     private fun handleDispose(result: MethodChannel.Result) {
         activity?.runOnUiThread {
-            playerCore?.dispose()
-            playerCore = null
-            Log.d(TAG, "Disposed")
-            result.success(null)
+            playerCore?.dispose {
+                playerCore = null
+                Log.d(TAG, "Disposed")
+                result.success(null)
+            } ?: run {
+                playerCore = null
+                result.success(null)
+            }
         } ?: result.success(null)
     }
 
diff --git a/lib/screens/video_player_screen.dart b/lib/screens/video_player_screen.dart
index 9969e8f5..01516cf3 100644
--- a/lib/screens/video_player_screen.dart
+++ b/lib/screens/video_player_screen.dart
@@ -1,5 +1,6 @@
 import 'dart:async';
 import 'dart:io';
+import 'dart:math';
 
 import 'package:flutter/material.dart';
 import 'package:plezy/widgets/app_icon.dart';
@@ -418,6 +419,29 @@ class VideoPlayerScreenState extends State<VideoPlayerScreen> with WidgetsBindin
       if (bufferSizeMB > 0) {
         final bufferSizeBytes = bufferSizeMB * 1024 * 1024;
         await player!.setProperty('demuxer-max-bytes', bufferSizeBytes.toString());
+        // Set back-buffer to 1/4 of forward buffer
+        final backBytes = bufferSizeBytes ~/ 4;
+        await player!.setProperty('demuxer-max-back-bytes', backBytes.toString());
+      }
+      if (Platform.isAndroid) {
+        // Cap demuxer buffers based on device heap to prevent OOM crashes.
+        // Without limits, mpv defaults can consume 225MB+ just for demuxer
+        // buffering, which combined with decoded frames and GPU textures
+        // exhausts the process address space on memory-constrained devices.
+        final heapMB = await PlayerAndroid.getHeapSize();
+        if (heapMB > 0) {
+          final autoBackMB = heapMB <= 256 ? 16 : (heapMB <= 512 ? 32 : 48);
+          if (bufferSizeMB == 0) {
+            // Auto mode: cap both forward and back buffer based on heap
+            final autoForwardMB = heapMB <= 256 ? 32 : (heapMB <= 512 ? 64 : 100);
+            await player!.setProperty('demuxer-max-bytes', '${autoForwardMB * 1024 * 1024}');
+            await player!.setProperty('demuxer-max-back-bytes', '${autoBackMB * 1024 * 1024}');
+          } else {
+            // Manual mode: cap back-buffer relative to heap if 1/4 ratio is too high
+            final maxBackBytes = min(bufferSizeMB * 1024 * 1024 ~/ 4, autoBackMB * 1024 * 1024);
+            await player!.setProperty('demuxer-max-back-bytes', maxBackBytes.toString());
+          }
+        }
       }
       await player!.setProperty('msg-level', debugLoggingEnabled ? 'all=debug' : 'all=error');
       await player!.setLogLevel(debugLoggingEnabled ? 'v' : 'warn');