DonutWare · GustavoGarufi · Jun 1, 2026
diff --git a/android/app/build.gradle b/android/app/build.gradle
@@ -71,6 +71,19 @@ android {
         targetSdk = flutter.targetSdkVersion
         versionCode = flutter.versionCode
         versionName = flutter.versionName
+
+        externalNativeBuild {
+            cmake {
+                cppFlags ""
+            }
+        }
+    }
+
+    externalNativeBuild {
+        cmake {
+            path "src/main/cpp/CMakeLists.txt"
+            version "3.22.1"
+        }
     }
 
     composeOptions {
@@ -139,6 +152,7 @@ dependencies {
     implementation("androidx.media3:media3-exoplayer-hls:$media3_version")
     implementation("org.jellyfin.media3:media3-ffmpeg-decoder:$media3_version")
     implementation("io.github.peerless2012:ass-media:0.3.0")
+    implementation("io.github.peerless2012:ass-kt:0.3.0")
 
     //UI
     implementation("io.github.rabehx:iconsax-compose:0.0.5")

diff --git a/android/app/src/main/cpp/CMakeLists.txt b/android/app/src/main/cpp/CMakeLists.txt
@@ -0,0 +1,7 @@
+cmake_minimum_required(VERSION 3.22.1)
+
+project(fladder_ass)
+
+add_library(fladder_ass SHARED fladder_ass.cpp)
+
+target_link_libraries(fladder_ass android log dl)
diff --git a/android/app/src/main/cpp/fladder_ass.cpp b/android/app/src/main/cpp/fladder_ass.cpp
@@ -0,0 +1,46 @@
+#include <jni.h>
+#include <dlfcn.h>
+#include <android/log.h>
+
+#define LOG_TAG "FladderAss"
+#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)
+
+extern "C"
+JNIEXPORT jboolean JNICALL
+Java_nl_jknaapen_fladder_player_AssFontConfigurator_nativeSetFonts(
+        JNIEnv *env,
+        jobject,
+        jlong nativeRenderer,
+        jstring defaultFontPath,
+        jstring defaultFamily
+) {
+    if (nativeRenderer == 0) {
+        LOGE("nativeSetFonts missing renderer");
+        return JNI_FALSE;
+    }
+
+    void *library = dlopen("libass.so", RTLD_NOW);
+    if (library == nullptr) {
+        LOGE("dlopen libass.so failed: %s", dlerror());
+        return JNI_FALSE;
+    }
+
+    typedef void (*AssSetFontsFn)(void *, const char *, const char *, int, const char *, int);
+    auto assSetFonts = reinterpret_cast<AssSetFontsFn>(dlsym(library, "ass_set_fonts"));
+    if (assSetFonts == nullptr) {
+        LOGE("dlsym ass_set_fonts failed: %s", dlerror());
+        return JNI_FALSE;
+    }
+
+    const char *fontPath = defaultFontPath == nullptr
+                           ? nullptr
+                           : env->GetStringUTFChars(defaultFontPath, nullptr);
+    const char *family = env->GetStringUTFChars(defaultFamily, nullptr);
+    // ASS_FONTPROVIDER_AUTODETECT is 1 in libass. update=true rebuilds provider after addFont().
+    assSetFonts(reinterpret_cast<void *>(nativeRenderer), fontPath, family, 1, nullptr, 1);
+    env->ReleaseStringUTFChars(defaultFamily, family);
+    if (fontPath != nullptr) {
+        env->ReleaseStringUTFChars(defaultFontPath, fontPath);
+    }
+    return JNI_TRUE;
+}
diff --git a/android/app/src/main/kotlin/nl/jknaapen/fladder/composables/dialogs/AudioSelection.kt b/android/app/src/main/kotlin/nl/jknaapen/fladder/composables/dialogs/AudioSelection.kt
@@ -21,7 +21,6 @@ import nl.jknaapen.fladder.objects.Localized
 import nl.jknaapen.fladder.objects.Translate
 import nl.jknaapen.fladder.objects.VideoPlayerObject
 import nl.jknaapen.fladder.utility.clearAudioTrack
-import nl.jknaapen.fladder.utility.setInternalAudioTrack
 
 @OptIn(UnstableApi::class)
 @Composable
@@ -33,11 +32,11 @@ fun AudioPicker(
     val audioTracks by VideoPlayerObject.audioTracks.collectAsState(emptyList())
     val internalAudioTracks by VideoPlayerObject.exoAudioTracks.collectAsState(emptyList())
 
-    if (internalAudioTracks.isEmpty()) return
+    if (audioTracks.isEmpty()) return
 
     val focusOffTrack = remember { FocusRequester() }
-    val focusRequesters = remember(internalAudioTracks) {
-        internalAudioTracks.associateWith { FocusRequester() }
+    val focusRequesters = remember(audioTracks) {
+        audioTracks.associateWith { FocusRequester() }
     }
 
     val listState = rememberLazyListState()
@@ -55,11 +54,8 @@ fun AudioPicker(
             return@LaunchedEffect
         }
 
-        val internalIndex = serverTrackIndex - 1
-        val lazyColumnIndex = internalIndex + 1
-
-        listState.scrollToItem(lazyColumnIndex)
-        focusRequesters[internalAudioTracks[internalIndex]]?.requestFocus()
+        listState.scrollToItem(serverTrackIndex)
+        focusRequesters[audioTracks[serverTrackIndex]]?.requestFocus()
     }
 
     CustomModalBottomSheet(
@@ -90,22 +86,20 @@ fun AudioPicker(
                 }
             }
 
-            internalAudioTracks.forEachIndexed { index, track ->
-                val serverTrack = audioTracks.elementAtOrNull(index + 1)
-                val selected = serverTrack?.index?.toInt() == selectedIndex
+            audioTracks.drop(1).forEachIndexed { index, serverTrack ->
+                val selected = serverTrack.index.toInt() == selectedIndex
 
                 item {
                     TrackButton(
                         modifier = Modifier
                             .fillMaxWidth()
-                            .focusRequester(focusRequesters[track]!!),
+                            .focusRequester(focusRequesters[serverTrack]!!),
                         onClick = {
-                            serverTrack?.index?.let { VideoPlayerObject.setAudioTrackIndex(it.toInt()) }
-                            player.setInternalAudioTrack(track)
+                            VideoPlayerObject.setAudioTrackIndex(serverTrack.index.toInt())
                         },
                         selected = selected
                     ) {
-                        Text(serverTrack?.name ?: "")
+                        Text(serverTrack.name)
                     }
                 }
             }

diff --git a/android/app/src/main/kotlin/nl/jknaapen/fladder/composables/dialogs/SubtitlePicker.kt b/android/app/src/main/kotlin/nl/jknaapen/fladder/composables/dialogs/SubtitlePicker.kt
@@ -22,7 +22,6 @@ import nl.jknaapen.fladder.objects.Localized
 import nl.jknaapen.fladder.objects.Translate
 import nl.jknaapen.fladder.objects.VideoPlayerObject
 import nl.jknaapen.fladder.utility.clearSubtitleTrack
-import nl.jknaapen.fladder.utility.setInternalSubtitleTrack
 
 @OptIn(UnstableApi::class)
 @Composable
@@ -32,7 +31,6 @@ fun SubtitlePicker(
 ) {
     val selectedIndex by VideoPlayerObject.currentSubtitleTrackIndex.collectAsState()
     val subTitles by VideoPlayerObject.subtitleTracks.collectAsState(emptyList())
-    val internalSubTracks by VideoPlayerObject.exoSubTracks.collectAsState(emptyList())
 
     if (subTitles.isEmpty()) return
 
@@ -75,15 +73,7 @@ fun SubtitlePicker(
                                 VideoPlayerObject.setSubtitleTrackIndex(-1)
                                 player.clearSubtitleTrack()
                             } else {
-                                val internalTrackIndex = index - 1
-
-                                val internalSubTrack =
-                                    internalSubTracks.elementAtOrNull(internalTrackIndex)
-
-                                if (internalSubTrack != null) {
-                                    VideoPlayerObject.setSubtitleTrackIndex(serverSub.index.toInt())
-                                    player.setInternalSubtitleTrack(internalSubTrack)
-                                }
+                                VideoPlayerObject.setSubtitleTrackIndex(serverSub.index.toInt())
                             }
                         },
                         selected = selected,
@@ -102,4 +92,4 @@ fun SubtitlePicker(
             }
         }
     }
-}
+}
diff --git a/android/app/src/main/kotlin/nl/jknaapen/fladder/messengers/VideoPlayerImplementation.kt b/android/app/src/main/kotlin/nl/jknaapen/fladder/messengers/VideoPlayerImplementation.kt
@@ -18,6 +18,9 @@ import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.map
 import nl.jknaapen.fladder.objects.PlayerSettingsObject
 import nl.jknaapen.fladder.objects.VideoPlayerObject
+import nl.jknaapen.fladder.player.FladderAssSidecarController
+import nl.jknaapen.fladder.player.isAssSubtitleTrack
+import nl.jknaapen.fladder.player.isAssSubtitleUrl
 import nl.jknaapen.fladder.utility.clearAudioTrack
 import nl.jknaapen.fladder.utility.clearSubtitleTrack
 import nl.jknaapen.fladder.utility.enableSubtitles
@@ -29,7 +32,12 @@ import kotlin.time.Duration.Companion.seconds
 
 class VideoPlayerImplementation(
 ) : VideoPlayerApi {
+    private companion object {
+        const val MAX_PRELOADED_SIDECAR_SUBTITLES = 25
+    }
+
     var player: ExoPlayer? = null
+    private var assSidecarController: FladderAssSidecarController? = null
     val playbackData: MutableStateFlow<PlayableData?> = MutableStateFlow(null)
 
     var subsInitialized = false
@@ -85,13 +93,41 @@ class VideoPlayerImplementation(
                     ignoreCase = true
                 )
                 val subTitles = playbackData.value?.subtitleTracks ?: listOf()
+                val playableData = playbackData.value
+                val useManualAssSidecars = playableData.usesManualAssSidecarPlayback()
+                val subtitleConfigurations = subTitles
+                    .filter { !it.url.isNullOrEmpty() }
+                    .let { subtitlesWithUrl ->
+                        if (useManualAssSidecars) {
+                            return@let subtitlesWithUrl.filterNot { it.isAssSubtitleTrack() }
+                        }
+                        val assTrackCount = subtitlesWithUrl.count { it.isAssSubtitleTrack() }
+                        if (
+                            sidecarSubtitlesCanPreload(
+                                subtitlesWithUrl.size,
+                                assTrackCount,
+                                MAX_PRELOADED_SIDECAR_SUBTITLES
+                            )
+                        ) {
+                            subtitlesWithUrl
+                        } else {
+                            val selectedSubtitleIndex = playbackData.value?.defaultSubtrack ?: -1
+                            subtitlesWithUrl.filter { it.index == selectedSubtitleIndex }
+                        }
+                    }
+                assSidecarController?.configure(
+                    subTitles,
+                    useManualAssSidecars,
+                    playableData?.defaultSubtrack ?: -1,
+                )
                 val mediaItemBuilder = MediaItem.Builder()
                     .setUri(url)
                     .setTag(playbackData.value?.currentItem?.title)
                     .setMediaId(playbackData.value?.currentItem?.id ?: "")
                     .setSubtitleConfigurations(
-                        subTitles.filter { it.external && !it.url.isNullOrEmpty() }.map { sub ->
+                        subtitleConfigurations.map { sub ->
                             MediaItem.SubtitleConfiguration.Builder(sub.url!!.toUri())
+                                .setId("fladder-sub-${sub.index}")
                                 .setMimeType(guessSubtitleMimeType(sub.url))
                                 .setLanguage(sub.languageCode)
                                 .setLabel(sub.name)
@@ -165,21 +201,63 @@ class VideoPlayerImplementation(
             open(playData.url, true, callback = {})
         }
     }
+
+    fun initAssSidecarController(controller: FladderAssSidecarController?) {
+        assSidecarController = controller
+    }
+
+    fun applySubtitleTrack(trackIndex: Int) {
+        val playableData = playbackData.value
+        if (playableData.usesManualAssSidecarPlayback()) {
+            val selectedSubtitle = playableData?.subtitleTracks
+                ?.firstOrNull { it.index.toInt() == trackIndex }
+            if (trackIndex < 0 || selectedSubtitle?.isAssSubtitleTrack() == true) {
+                assSidecarController?.select(trackIndex.toLong())
+                player?.clearSubtitleTrack()
+                return
+            }
+            assSidecarController?.select(-1)
+        }
+        player?.selectSubtitleTrack(playbackData.value, trackIndex)
+    }
+
+    fun applyAudioTrack(trackIndex: Int) {
+        player?.selectAudioTrack(playbackData.value, trackIndex)
+    }
+
 }
 
 fun guessSubtitleMimeType(fileName: String): String = when {
     fileName.contains(".srt", ignoreCase = true) -> MimeTypes.APPLICATION_SUBRIP
     fileName.contains(".vtt", ignoreCase = true) -> MimeTypes.TEXT_VTT
     fileName.contains(".ass", ignoreCase = true) -> MimeTypes.TEXT_SSA
+    fileName.contains(".ssa", ignoreCase = true) -> MimeTypes.TEXT_SSA
     else -> MimeTypes.APPLICATION_SUBRIP
 }
 
+private fun sidecarSubtitlesCanPreload(total: Int, assTrackCount: Int, maxPreloaded: Int = 25): Boolean =
+    total <= maxPreloaded && assTrackCount <= 1
+
+private fun PlayableData?.usesManualAssSidecarPlayback(maxPreloaded: Int = 25): Boolean {
+    if (this?.mediaInfo?.playbackType != PlaybackType.TRANSCODED) return false
+    val subtitlesWithUrl = subtitleTracks.filter { !it.url.isNullOrEmpty() }
+    return subtitlesWithUrl.size <= maxPreloaded && subtitlesWithUrl.any {
+        it.isAssSubtitleTrack()
+    }
+}
+
 fun ExoPlayer.properlySetSubAndAudioTracks(playableData: PlayableData) {
     if (playableData.mediaInfo.playbackType == PlaybackType.TV) {
         // In TV mode, do not set tracks here as they are handled differently
         return
     }
     try {
+        if (playableData.mediaInfo.playbackType == PlaybackType.TRANSCODED) {
+            selectSubtitleTrack(playableData, playableData.defaultSubtrack.toInt())
+            clearAudioTrack(false)
+            return
+        }
+
         val currentSubIndex = playableData.defaultSubtrack
         val indexOfSubtitleTrack =
             playableData.subtitleTracks.indexOfFirst { it.index == currentSubIndex }
@@ -188,7 +266,7 @@ fun ExoPlayer.properlySetSubAndAudioTracks(playableData: PlayableData) {
         val wantedSubIndex = indexOfSubtitleTrack - 1
         if (wantedSubIndex < 0) {
             clearSubtitleTrack()
-        } else {
+        } else if (wantedSubIndex < internalSubTracks.size) {
             enableSubtitles()
             setInternalSubtitleTrack(internalSubTracks[wantedSubIndex])
         }
@@ -201,11 +279,55 @@ fun ExoPlayer.properlySetSubAndAudioTracks(playableData: PlayableData) {
         val wantedAudioIndex = indexOfAudioTrack - 1
         if (wantedAudioIndex < 0) {
             clearAudioTrack()
-        } else {
+        } else if (wantedAudioIndex < internalAudioTracks.size) {
             clearAudioTrack(false)
             setInternalAudioTrack(internalAudioTracks[wantedAudioIndex])
         }
     } catch (e: Exception) {
         e.printStackTrace()
     }
 }
+
+fun ExoPlayer.selectSubtitleTrack(playableData: PlayableData?, selectedSubIndex: Int) {
+    if (playableData == null) return
+    if (selectedSubIndex < 0) {
+        clearSubtitleTrack()
+        return
+    }
+
+    val internalSubTracks = getSubtitleTracks()
+    val wantedSubIndex = when (playableData.mediaInfo.playbackType) {
+        PlaybackType.TRANSCODED -> {
+            val subtitlesWithUrl = playableData.subtitleTracks.filter { !it.url.isNullOrEmpty() }
+            val selectableSubtitles = if (playableData.usesManualAssSidecarPlayback()) {
+                subtitlesWithUrl.filterNot { it.isAssSubtitleTrack() }
+            } else {
+                subtitlesWithUrl
+            }
+            val assTrackCount = subtitlesWithUrl.count { it.isAssSubtitleTrack() }
+            if (sidecarSubtitlesCanPreload(subtitlesWithUrl.size, assTrackCount)) {
+                selectableSubtitles.indexOfFirst { it.index.toInt() == selectedSubIndex }
+            } else {
+                0
+            }
+        }
+
+        else -> playableData.subtitleTracks.indexOfFirst { it.index.toInt() == selectedSubIndex } - 1
+    }
+
+    internalSubTracks.elementAtOrNull(wantedSubIndex)?.let { setInternalSubtitleTrack(it) }
+}
+
+fun ExoPlayer.selectAudioTrack(playableData: PlayableData?, selectedAudioIndex: Int) {
+    if (playableData == null || playableData.mediaInfo.playbackType == PlaybackType.TRANSCODED) return
+    val internalAudioTracks = getAudioTracks()
+    val wantedAudioIndex = playableData.audioTracks.indexOfFirst { it.index.toInt() == selectedAudioIndex } - 1
+    if (wantedAudioIndex < 0) {
+        clearAudioTrack()
+    } else {
+        internalAudioTracks.elementAtOrNull(wantedAudioIndex)?.let {
+            clearAudioTrack(false)
+            setInternalAudioTrack(it)
+        }
+    }
+}