Try using low latency for WebRTC HEVC encoder if available

youennf · youennf · commit d7ef486d1adc · 2023-01-19T23:52:32.000-08:00
https://bugs.webkit.org/show_bug.cgi?id=250824 rdar://problem/104416138 Reviewed by Eric Carlson. Try using low latency mode and if failing use regular mode. * Source/ThirdParty/libwebrtc/Source/webrtc/sdk/objc/components/video_codec/RTCVideoEncoderH265.mm: (-[RTCVideoEncoderH265 resetCompressionSession]): Canonical link: https://commits.webkit.org/259128@main
diff --git a/Source/ThirdParty/libwebrtc/Source/webrtc/sdk/objc/components/video_codec/RTCVideoEncoderH265.mm b/Source/ThirdParty/libwebrtc/Source/webrtc/sdk/objc/components/video_codec/RTCVideoEncoderH265.mm
@@ -36,6 +36,8 @@
 #include "sdk/objc/Framework/Classes/VideoToolbox/nalu_rewriter.h"
 #include "system_wrappers/include/clock.h"
 
+VT_EXPORT const CFStringRef kVTVideoEncoderSpecification_RequiredLowLatency;
+
 @interface RTCVideoEncoderH265 ()
 
 - (void)frameWasEncoded:(OSStatus)status
@@ -407,8 +409,7 @@ - (int)resetCompressionSession {
   CFDictionarySetValue(encoder_specs, kVTVideoEncoderSpecification_EnableHardwareAcceleratedVideoEncoder, kCFBooleanTrue);
 #endif
 #if HAVE_VTB_REQUIREDLOWLATENCY
-  // We will want to enable this property once working.
-  // CFDictionarySetValue(encoder_specs, kVTVideoEncoderSpecification_RequiredLowLatency, kCFBooleanTrue);
+  CFDictionarySetValue(encoder_specs, kVTVideoEncoderSpecification_RequiredLowLatency, kCFBooleanTrue);
 #endif
   OSStatus status = VTCompressionSessionCreate(
       nullptr,  // use default allocator
@@ -417,6 +418,17 @@ - (int)resetCompressionSession {
       sourceAttributes,
       nullptr,  // use default compressed data allocator
       compressionOutputCallback, nullptr, &_compressionSession);
+  if (status != noErr) {
+    if (encoder_specs)
+      CFDictionaryRemoveValue(encoder_specs, kVTVideoEncoderSpecification_RequiredLowLatency);
+    status = VTCompressionSessionCreate(
+        nullptr,  // use default allocator
+        _width, _height, kCMVideoCodecType_HEVC,
+        encoder_specs,  // use hardware accelerated encoder if available
+        sourceAttributes,
+        nullptr,  // use default compressed data allocator
+        compressionOutputCallback, nullptr, &_compressionSession);
+  }
   if (sourceAttributes) {
     CFRelease(sourceAttributes);
     sourceAttributes = nullptr;
