Implement ability to limit libass memory and to control target fps

Author: JustAMan

Makefile

@@ -293,7 +293,7 @@ src/subtitles-octopus-worker.bc: dist/libraries/lib/libass.a src/Makefile src/su
 # Dist Files
 EMCC_COMMON_ARGS = \
 	$(GLOBAL_CFLAGS) \
-	-s EXPORTED_FUNCTIONS="['_main', '_malloc', '_libassjs_render_blend', '_free']" \
+	-s EXPORTED_FUNCTIONS="['_main', '_malloc', '_libassjs_render_blend', '_libassjs_set_memory_limit']" \
 	-s EXTRA_EXPORTED_RUNTIME_METHODS="['ccall', 'cwrap', 'getValue', 'FS_createPreloadedFile', 'FS_createFolder']" \
 	-s NO_EXIT_RUNTIME=1 \
 	--use-preload-plugins \

src/SubtitleOctopus.cpp

@@ -212,6 +212,13 @@ class SubtitleOctopus {
     }
 };
 
+void libassjs_set_memory_limit(int limit) {
+    if (limit > 0) {
+        printf("libass: setting total libass memory limit to %d MiB\n", limit);
+        ass_set_cache_limits(ass_renderer, 0, limit);
+    }
+}
+
 const float MIN_UINT8_CAST = 0.9 / 255;
 const float MAX_UINT8_CAST = 255.9 / 255;
 

src/post-worker.js

@@ -7,6 +7,7 @@ self.rafId = null;
 self.nextIsRaf = false;
 self.lastCurrentTimeReceivedAt = Date.now();
 self.targetFps = 30;
+self.libassMemoryLimit = 0; // in MiB
 
 self.width = 0;
 self.height = 0;
@@ -547,6 +548,8 @@ function onMessageFromMainEmscriptenThread(message) {
                     Module.canvas.boundingClientRect = message.data.boundingClientRect;
                 }
             }
+            self.targetFps = message.data.targetFps || self.targetFps;
+            self.libassMemoryLimit = message.data.libassMemoryLimit || self.libassMemoryLimit;
             removeRunDependency('worker-init');
             break;
         }

src/pre-worker.js

@@ -93,6 +93,7 @@ Module['onRuntimeInitialized'] = function () {
     self.octObj = new Module.SubtitleOctopus();
 
     self._render_blend = Module['cwrap']('libassjs_render_blend', null, ['number', 'number', 'number', 'number', 'number', 'number', 'number', 'number']);
+    self._set_memory_limit = Module['cwrap']('libassjs_set_memory_limit', null, ['number']);
 
     self.changed = Module._malloc(4);
 
@@ -107,6 +108,9 @@ Module['onRuntimeInitialized'] = function () {
     self.ass_track = self.octObj.track;
     self.ass_library = self.octObj.ass_library;
     self.ass_renderer = self.octObj.ass_renderer;
+    if (self.libassMemoryLimit > 0) {
+        self._set_memory_limit(self.libassMemoryLimit);
+    }
 };
 
 Module["print"] = function (text) {

src/subtitles-octopus.js

@@ -14,6 +14,8 @@ var SubtitlesOctopus = function (options) {
     var self = this;
     self.canvas = options.canvas; // HTML canvas element (optional if video specified)
     self.renderMode = options.lossyRender ? 'fast' : (options.blendRender ? 'blend' : 'normal');
+    self.libassMemoryLimit = options.libassMemoryLimit || 0;
+    self.targetFps = options.targetFps || undefined;
     self.isOurCanvas = false; // (internal) we created canvas and manage it
     self.video = options.video; // HTML video element (optional if canvas specified)
     self.canvasParent = null; // (internal) HTML canvas parent element
@@ -28,7 +30,7 @@ var SubtitlesOctopus = function (options) {
     self.subUrl = options.subUrl; // Link to sub file (optional if subContent specified)
     self.subContent = options.subContent || null; // Sub content (optional if subUrl specified)
     self.onErrorEvent = options.onError; // Function called in case of critical error meaning sub wouldn't be shown and you should use alternative method (for instance it occurs if browser doesn't support web workers).
-    self.debug = options.debug || false; // When debug enabled, some performance info printed in console.
+    self.debug = options.debug || false;  // When debug enabled, some performance info printed in console.
     self.lastRenderTime = 0; // (internal) Last time we got some frame from worker
     self.pixelRatio = window.devicePixelRatio || 1; // (internal) Device pixel ratio (for high dpi devices)
 
@@ -104,7 +106,9 @@ var SubtitlesOctopus = function (options) {
             subContent: self.subContent,
             fonts: self.fonts,
             availableFonts: self.availableFonts,
-            debug: self.debug
+            debug: self.debug,
+            targetFps: self.targetFps,
+            libassMemoryLimit: self.libassMemoryLimit
         });
     };
 
@@ -253,9 +257,9 @@ var SubtitlesOctopus = function (options) {
         }
         if (self.debug) {
             var drawTime = Math.round(performance.now() - beforeDrawTime);
-            var blendTime = data.blendTime || 0;
-            if (blendTime > 0) {
-                console.log('render: ' + Math.round(data.spentTime - blendTime) + ' ms, blend: ' + Math.round(blendTime) + ' ms, draw: ' + drawTime + ' ms');
+            var blendTime = data.blendTime;
+            if (typeof blendTime !== 'undefined') {
+                console.log('render: ' + Math.round(data.spentTime - blendTime) + ' ms, blend: ' + Math.round(blendTime) + ' ms, draw: ' + drawTime + ' ms; TOTAL=' + Math.round(data.spentTime + drawTime) + ' ms');
             } else {
                 console.log(Math.round(data.spentTime) + ' ms (+ ' + drawTime + ' ms draw)');
             }