Reduce parsing overhead https://bugs.webkit.org/show_bug.cgi?id=290189

Reviewed by Philippe Normand.

We can save some overhead by not parsing again streams that are already parsed
and that the caps match the decoder's.

In that case, we can skip creating a parser element in parsebin.

* Source/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.cpp:
(WebCore::MediaPlayerPrivateGStreamer::configureParsebin):
(WebCore::MediaPlayerPrivateGStreamer::configureElement):
* Source/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.h:

Canonical link: https://commits.webkit.org/292591@main

Author: cadubentzen

Source/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.cpp

@@ -2506,6 +2506,43 @@ void MediaPlayerPrivateGStreamer::processTableOfContentsEntry(GstTocEntry* entry
         processTableOfContentsEntry(static_cast<GstTocEntry*>(i->data));
 }
 
+void MediaPlayerPrivateGStreamer::configureParsebin(GstElement* parsebin)
+{
+    // We can save some overhead by not parsing again streams that are already parsed and that
+    // the caps match the decoder's. In that case, we can skip creating a parser element in parsebin.
+    g_signal_connect(parsebin, "autoplug-select",
+        G_CALLBACK(+[](GstElement*, GstPad*, GstCaps* caps, GstElementFactory* factory, MediaPlayerPrivateGStreamer* player) -> unsigned {
+            static auto tryAutoPlug = *gstGetAutoplugSelectResult("try"_s);
+            static auto exposeAutoPlug = *gstGetAutoplugSelectResult("expose"_s);
+
+            auto* structure = gst_caps_get_structure(caps, 0);
+            if (!structure)
+                return tryAutoPlug;
+
+            // TODO: this already works perfectly well for MediaStream, but in MSE we still plug in a parser despite having
+            // already parsed the stream in the append pipeline, because the caps we receive here aren't parsed yet,
+            // although it becomes parsed later. We can probably find a way to avoid this extra parsing in MSE too.
+            auto isParsed = gstStructureGet<bool>(structure, "parsed"_s);
+            if (!isParsed || !*isParsed)
+                return tryAutoPlug;
+
+            auto& scanner = GStreamerRegistryScanner::singleton();
+            GUniquePtr<char> gstCodecName(gst_codec_utils_caps_get_mime_codec(caps));
+            auto codecName = String::fromUTF8(gstCodecName.get());
+            auto result = scanner.isCodecSupported(GStreamerRegistryScanner::Configuration::Decoding, codecName);
+            if (!result.isSupported)
+                return tryAutoPlug;
+
+            auto decoderFactoryAcceptsCaps = gst_element_factory_can_sink_any_caps(result.factory.get(), caps);
+            GST_DEBUG_OBJECT(player->pipeline(), "Does %" GST_PTR_FORMAT " decoder accept caps %" GST_PTR_FORMAT "? %s", factory, caps, boolForPrinting(decoderFactoryAcceptsCaps));
+
+            if (decoderFactoryAcceptsCaps)
+                return exposeAutoPlug;
+
+            return tryAutoPlug;
+        }), this);
+}
+
 void MediaPlayerPrivateGStreamer::configureElement(GstElement* element)
 {
     configureElementPlatformQuirks(element);
@@ -2521,6 +2558,9 @@ void MediaPlayerPrivateGStreamer::configureElement(GstElement* element)
     if (webkitGstCheckVersion(1, 22, 0) && g_str_has_prefix(elementName.get(), "urisourcebin") && (isMediaSource() || isMediaStreamPlayer()))
         g_object_set(element, "use-buffering", FALSE, "parse-streams", !isMediaStreamPlayer(), nullptr);
 
+    if (nameView.startsWith("parsebin"_s))
+        configureParsebin(element);
+
     // In case of playbin3 with <video ... preload="auto">, instantiate
     // downloadbuffer element, otherwise the playbin3 would instantiate
     // a queue element instead .

Source/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.h

@@ -578,6 +578,7 @@ class MediaPlayerPrivateGStreamer
     void configureAudioDecoder(GstElement*);
     void configureVideoDecoder(GstElement*);
     void configureElement(GstElement*);
+    void configureParsebin(GstElement*);
 
     void configureElementPlatformQuirks(GstElement*);