Implement WebCodecs video encoder flush

https://bugs.webkit.org/show_bug.cgi?id=246686 rdar://problem/101288914 Reviewed by Eric Carlson. Implement remote encoder flush by sending an IPC to GPUProcess to flush encoders. Drive-by fix to make full-cycle-test.https.any_h264_avc test pass by providing the correct AVC description by looking at the sample buffer format description. Covered by rebased tests. * LayoutTests/imported/w3c/web-platform-tests/webcodecs/full-cycle-test.https.any_h264_annexb-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/webcodecs/full-cycle-test.https.any_h264_avc-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/webcodecs/reconfiguring-encoder.https.any_h264_annexb-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/webcodecs/reconfiguring-encoder.https.any_h264_avc-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/webcodecs/temporal-svc-encoding.https.any_h264-expected.txt: * Source/ThirdParty/libwebrtc/Configurations/libwebrtc.iOS.exp: * Source/ThirdParty/libwebrtc/Configurations/libwebrtc.iOSsim.exp: * Source/ThirdParty/libwebrtc/Configurations/libwebrtc.mac.exp: * Source/ThirdParty/libwebrtc/Source/webrtc/sdk/WebKit/WebKitEncoder.h: * Source/ThirdParty/libwebrtc/Source/webrtc/sdk/WebKit/WebKitEncoder.mm: (-[WK_RTCLocalVideoH264H265Encoder flush]): (webrtc::flushLocalEncoder): * Source/ThirdParty/libwebrtc/Source/webrtc/sdk/objc/components/video_codec/RTCVideoEncoderH264.h: * Source/ThirdParty/libwebrtc/Source/webrtc/sdk/objc/components/video_codec/RTCVideoEncoderH264.mm: (-[RTCVideoEncoderH264 setUseAnnexB:]): (-[RTCVideoEncoderH264 configureCompressionSession]): (-[RTCVideoEncoderH264 setEncoderBitrateBps:frameRate:]): (-[RTCVideoEncoderH264 frameWasEncoded🎏sampleBuffer:codecSpecificInfo:width:height:renderTimeMs:timestamp:rotation:isKeyFrameRequired:]): (-[RTCVideoEncoderH264 flush]): * Source/ThirdParty/libwebrtc/Source/webrtc/sdk/objc/components/video_codec/RTCVideoEncoderH265.h: * Source/ThirdParty/libwebrtc/Source/webrtc/sdk/objc/components/video_codec/RTCVideoEncoderH265.mm: (-[RTCVideoEncoderH265 setUseAnnexB:]): (-[RTCVideoEncoderH265 frameWasEncoded🎏sampleBuffer:width:height:renderTimeMs:timestamp:rotation:]): (-[RTCVideoEncoderH265 flush]): * Source/WebKit/GPUProcess/webrtc/LibWebRTCCodecsProxy.h: * Source/WebKit/GPUProcess/webrtc/LibWebRTCCodecsProxy.messages.in: * Source/WebKit/GPUProcess/webrtc/LibWebRTCCodecsProxy.mm: (WebKit::LibWebRTCCodecsProxy::flushEncoder): * Source/WebKit/WebProcess/GPU/media/RemoteVideoCodecFactory.cpp: (WebKit::RemoteVideoEncoder::flush): * Source/WebKit/WebProcess/GPU/webrtc/LibWebRTCCodecs.cpp: (WebKit::LibWebRTCCodecs::createEncoderAndWaitUntilReady): (WebKit::LibWebRTCCodecs::createEncoderInternal): (WebKit::LibWebRTCCodecs::flushEncoder): (WebKit::LibWebRTCCodecs::flushEncoderCompleted): * Source/WebKit/WebProcess/GPU/webrtc/LibWebRTCCodecs.h: * Source/WebKit/WebProcess/GPU/webrtc/LibWebRTCCodecs.messages.in: Canonical link: https://commits.webkit.org/255785@main
WebKit · Oct 20, 2022 · 7cf8c6db3ef5499b2a5c5d92fa14ffe329e7d009 · 7cf8c6d
1 parent 6f0bde8
commit 7cf8c6db3ef5499b2a5c5d92fa14ffe329e7d009
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Showing 21 changed files with 218 additions and 106 deletions.
diff --git a/...orted/w3c/web-platform-tests/webcodecs/full-cycle-test.https.any_h264_annexb-expected.txt b/...orted/w3c/web-platform-tests/webcodecs/full-cycle-test.https.any_h264_annexb-expected.txt
@@ -1,4 +1,3 @@
-CONSOLE MESSAGE: Error: assert_unreached: Decoder failure Reached unreachable code
 
-FAIL Encoding and decoding cycle promise_test: Unhandled rejection with value: object "AbortError: aborting flush as decoder is reset"
+PASS Encoding and decoding cycle
 
diff --git a/...imported/w3c/web-platform-tests/webcodecs/full-cycle-test.https.any_h264_avc-expected.txt b/...imported/w3c/web-platform-tests/webcodecs/full-cycle-test.https.any_h264_avc-expected.txt
@@ -1,11 +1,3 @@
-CONSOLE MESSAGE: DataError: Key frame is required
-CONSOLE MESSAGE: DataError: Key frame is required
 
-Harness Error (FAIL), message = DataError: Key frame is required
-
-TIMEOUT Encoding and decoding cycle Test timed out
-
-Harness Error (FAIL), message = DataError: Key frame is required
-
-TIMEOUT Encoding and decoding cycle Test timed out
+PASS Encoding and decoding cycle
 
diff --git a/...w3c/web-platform-tests/webcodecs/reconfiguring-encoder.https.any_h264_annexb-expected.txt b/...w3c/web-platform-tests/webcodecs/reconfiguring-encoder.https.any_h264_annexb-expected.txt
@@ -1,6 +1,7 @@
 CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
+CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
 
 Harness Error (FAIL), message = Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
 
-FAIL Reconfiguring encoder assert_equals: expected 16 but got 1
+PASS Reconfiguring encoder
 
diff --git a/...ed/w3c/web-platform-tests/webcodecs/reconfiguring-encoder.https.any_h264_avc-expected.txt b/...ed/w3c/web-platform-tests/webcodecs/reconfiguring-encoder.https.any_h264_avc-expected.txt
@@ -1,37 +1,7 @@
 CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
 CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
-CONSOLE MESSAGE: Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
 
-Harness Error (FAIL), message = Error: assert_unreached: assert_equals: expected 640 but got 800 Reached unreachable code
+Harness Error (FAIL), message = Error: assert_unreached: assert_equals: expected 800 but got 640 Reached unreachable code
 
 PASS Reconfiguring encoder
 
diff --git a/...ported/w3c/web-platform-tests/webcodecs/temporal-svc-encoding.https.any_h264-expected.txt b/...ported/w3c/web-platform-tests/webcodecs/temporal-svc-encoding.https.any_h264-expected.txt
@@ -1,8 +1,54 @@
 CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
 CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
+CONSOLE MESSAGE: Error: assert_own_property: expected property "svc" missing
 
 Harness Error (FAIL), message = Error: assert_own_property: expected property "svc" missing
 
-FAIL SVC L1T2 assert_equals: expected 24 but got 1
-FAIL SVC L1T3 assert_equals: expected 24 but got 1
+FAIL SVC L1T2 assert_equals: expected 12 but got 0
+FAIL SVC L1T3 assert_equals: expected 6 but got 0
 
diff --git a/Source/ThirdParty/libwebrtc/Configurations/libwebrtc.iOS.exp b/Source/ThirdParty/libwebrtc/Configurations/libwebrtc.iOS.exp
@@ -219,6 +219,7 @@ __ZN6webrtc18createLocalEncoderERKNS_14SdpVideoFormatEbU13block_pointerFvPKhmRKN
 __ZN6webrtc14SdpVideoFormatD1Ev
 __ZN6webrtc19releaseLocalEncoderEPv
 __ZN6webrtc23encodeLocalEncoderFrameEPvP10__CVBufferxjNS_13VideoRotationEb
+__ZN6webrtc17flushLocalEncoderEPv
 __ZN3rtc17CopyOnWriteBuffer24UnshareAndEnsureCapacityEm
 __ZN3rtc6Thread14InvokeInternalERKNS_8LocationENS_12FunctionViewIFvvEEE
 __ZN6webrtc18RtpSenderInterface38SetEncoderToPacketizerFrameTransformerEN3rtc13scoped_refptrINS_25FrameTransformerInterfaceEEE

diff --git a/Source/ThirdParty/libwebrtc/Configurations/libwebrtc.iOSsim.exp b/Source/ThirdParty/libwebrtc/Configurations/libwebrtc.iOSsim.exp
@@ -219,6 +219,7 @@ __ZN6webrtc18createLocalEncoderERKNS_14SdpVideoFormatEbU13block_pointerFvPKhmRKN
 __ZN6webrtc14SdpVideoFormatD1Ev
 __ZN6webrtc19releaseLocalEncoderEPv
 __ZN6webrtc23encodeLocalEncoderFrameEPvP10__CVBufferxjNS_13VideoRotationEb
+__ZN6webrtc17flushLocalEncoderEPv
 __ZN3rtc17CopyOnWriteBuffer24UnshareAndEnsureCapacityEm
 __ZN3rtc6Thread14InvokeInternalERKNS_8LocationENS_12FunctionViewIFvvEEE
 __ZN6webrtc18RtpSenderInterface38SetEncoderToPacketizerFrameTransformerEN3rtc13scoped_refptrINS_25FrameTransformerInterfaceEEE

diff --git a/Source/ThirdParty/libwebrtc/Configurations/libwebrtc.mac.exp b/Source/ThirdParty/libwebrtc/Configurations/libwebrtc.mac.exp
@@ -219,6 +219,7 @@ __ZN6webrtc18createLocalEncoderERKNS_14SdpVideoFormatEbU13block_pointerFvPKhmRKN
 __ZN6webrtc14SdpVideoFormatD1Ev
 __ZN6webrtc19releaseLocalEncoderEPv
 __ZN6webrtc23encodeLocalEncoderFrameEPvP10__CVBufferxjNS_13VideoRotationEb
+__ZN6webrtc17flushLocalEncoderEPv
 __ZN3rtc17CopyOnWriteBuffer24UnshareAndEnsureCapacityEm
 __ZN3rtc6Thread14InvokeInternalERKNS_8LocationENS_12FunctionViewIFvvEEE
 __ZN6webrtc18RtpSenderInterface38SetEncoderToPacketizerFrameTransformerEN3rtc13scoped_refptrINS_25FrameTransformerInterfaceEEE

diff --git a/Source/ThirdParty/libwebrtc/Source/webrtc/sdk/WebKit/WebKitEncoder.h b/Source/ThirdParty/libwebrtc/Source/webrtc/sdk/WebKit/WebKitEncoder.h
@@ -82,6 +82,7 @@ void encodeLocalEncoderFrame(LocalEncoder, CVPixelBufferRef, int64_t timeStampNs
 void setLocalEncoderRates(LocalEncoder, uint32_t bitRate, uint32_t frameRate);
 void setLocalEncoderLowLatency(LocalEncoder, bool isLowLatencyEnabled);
 void encoderVideoTaskComplete(void*, webrtc::VideoCodecType, const uint8_t* buffer, size_t length, const WebKitEncodedFrameInfo&);
+void flushLocalEncoder(LocalEncoder);
 
 template<class Decoder>
 bool WebKitEncodedFrameInfo::decode(Decoder& decoder, WebKitEncodedFrameInfo& info)

diff --git a/Source/ThirdParty/libwebrtc/Source/webrtc/sdk/WebKit/WebKitEncoder.mm b/Source/ThirdParty/libwebrtc/Source/webrtc/sdk/WebKit/WebKitEncoder.mm
@@ -50,6 +50,7 @@ - (int)setBitrate:(uint32_t)bitrateKbit framerate:(uint32_t)framerate;
 - (void)setLowLatency:(bool)lowLatencyEnabled;
 - (void)setUseAnnexB:(bool)useAnnexB;
 - (void)setDescriptionCallback:(RTCVideoEncoderDescriptionCallback)callback;
+- (void)flush;
 @end
 
 @implementation WK_RTCLocalVideoH264H265Encoder {
@@ -123,6 +124,14 @@ - (void)setDescriptionCallback:(RTCVideoEncoderDescriptionCallback)callback {
     }
     [m_h265Encoder setDescriptionCallback:callback];
 }
+
+- (void)flush {
+    if (m_h264Encoder) {
+        [m_h264Encoder flush];
+        return;
+    }
+    [m_h265Encoder flush];
+}
 @end
 
 namespace webrtc {
@@ -406,4 +415,10 @@ void setLocalEncoderLowLatency(LocalEncoder localEncoder, bool isLowLatencyEnabl
     [encoder setLowLatency:isLowLatencyEnabled];
 }
 
+void flushLocalEncoder(LocalEncoder localEncoder)
+{
+    auto *encoder = (__bridge WK_RTCLocalVideoH264H265Encoder *)(localEncoder);
+    [encoder flush];
+}
+
 }
diff --git a/.../ThirdParty/libwebrtc/Source/webrtc/sdk/objc/components/video_codec/RTCVideoEncoderH264.h b/.../ThirdParty/libwebrtc/Source/webrtc/sdk/objc/components/video_codec/RTCVideoEncoderH264.h
@@ -22,4 +22,5 @@ __attribute__((objc_runtime_name("WK_RTCVideoEncoderH264")))
 - (void)setH264LowLatencyEncoderEnabled:(bool)enabled;
 - (void)setUseAnnexB:(bool)useAnnexB;
 - (void)setDescriptionCallback:(RTCVideoEncoderDescriptionCallback)callback;
+- (void)flush;
 @end
diff --git a/...ThirdParty/libwebrtc/Source/webrtc/sdk/objc/components/video_codec/RTCVideoEncoderH264.mm b/...ThirdParty/libwebrtc/Source/webrtc/sdk/objc/components/video_codec/RTCVideoEncoderH264.mm
@@ -364,6 +364,7 @@ @implementation RTCVideoEncoderH264 {
   uint32_t _frameCount;
   int64_t _lastFrameRateEstimationTime;
   bool _useAnnexB;
+  bool _needsToSendDescription;
   RTCVideoEncoderDescriptionCallback _descriptionCallback;
 }
 
@@ -443,6 +444,7 @@ - (NSInteger)startEncodeWithSettings:(RTCVideoEncoderSettings *)settings
 - (void)setUseAnnexB:(bool)useAnnexB
 {
     _useAnnexB = useAnnexB;
+    _needsToSendDescription = !useAnnexB;
 }
 
 - (void)setDescriptionCallback:(RTCVideoEncoderDescriptionCallback)callback
@@ -844,7 +846,7 @@ - (void)configureCompressionSession {
   RTC_DCHECK([self hasCompressionSession]);
   SetVTSessionProperty(_vtCompressionSession, _vcpCompressionSession, kVTCompressionPropertyKey_RealTime, true);
 #if ENABLE_VCP_FOR_H264_BASELINE
-  if (_useBaseline && _useVCP)
+  if (_useBaseline && _useVCP && _isH264LowLatencyEncoderEnabled)
     SetVTSessionProperty(_vtCompressionSession, _vcpCompressionSession, kVTCompressionPropertyKey_ProfileLevel, kVTProfileLevel_H264_ConstrainedBaseline_AutoLevel);
   else
 #endif
@@ -907,29 +909,30 @@ - (void)setEncoderBitrateBps:(uint32_t)bitrateBps frameRate:(uint32_t)frameRate
           _vtCompressionSession, _vcpCompressionSession, kVTCompressionPropertyKey_ExpectedFrameRate, frameRate);
     }
 
-    // TODO(tkchin): Add a helper method to set array value.
-    int64_t dataLimitBytesPerSecondValue =
-        static_cast<int64_t>(_isBelowExpectedFrameRate ? actualTarget / 8 : actualTarget * kLimitToAverageBitRateFactor / 8);
-    CFNumberRef bytesPerSecond =
-        CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt64Type, &dataLimitBytesPerSecondValue);
-    int64_t oneSecondValue = 1;
-    CFNumberRef oneSecond =
-        CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt64Type, &oneSecondValue);
-    const void *nums[2] = {bytesPerSecond, oneSecond};
-    CFArrayRef dataRateLimits = CFArrayCreate(nullptr, nums, 2, &kCFTypeArrayCallBacks);
-
-    SetVTSessionProperty(_vtCompressionSession, _vcpCompressionSession, kVTCompressionPropertyKey_DataRateLimits, dataRateLimits);
-
-    if (bytesPerSecond) {
-      CFRelease(bytesPerSecond);
-    }
-    if (oneSecond) {
-      CFRelease(oneSecond);
-    }
-    if (dataRateLimits) {
-      CFRelease(dataRateLimits);
+    if (_isH264LowLatencyEncoderEnabled) {
+      // TODO(tkchin): Add a helper method to set array value.
+      int64_t dataLimitBytesPerSecondValue =
+          static_cast<int64_t>(_isBelowExpectedFrameRate ? actualTarget / 8 : actualTarget * kLimitToAverageBitRateFactor / 8);
+      CFNumberRef bytesPerSecond =
+          CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt64Type, &dataLimitBytesPerSecondValue);
+      int64_t oneSecondValue = 1;
+      CFNumberRef oneSecond =
+          CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt64Type, &oneSecondValue);
+      const void *nums[2] = {bytesPerSecond, oneSecond};
+      CFArrayRef dataRateLimits = CFArrayCreate(nullptr, nums, 2, &kCFTypeArrayCallBacks);
+
+      SetVTSessionProperty(_vtCompressionSession, _vcpCompressionSession, kVTCompressionPropertyKey_DataRateLimits, dataRateLimits);
+
+      if (bytesPerSecond) {
+        CFRelease(bytesPerSecond);
+      }
+      if (oneSecond) {
+        CFRelease(oneSecond);
+      }
+      if (dataRateLimits) {
+        CFRelease(dataRateLimits);
+      }
     }
-
     _encoderBitrateBps = bitrateBps;
     _encoderFrameRate = frameRate;
   }
@@ -1006,22 +1009,30 @@ - (void)frameWasEncoded:(OSStatus)status
       return;
     }
   } else {
-    if (_descriptionCallback) {
-      buffer->SetSize(0);
-      CMBlockBufferRef blockBuffer = CMSampleBufferGetDataBuffer(sampleBuffer);
-      size_t currentStart = 0;
-      size_t size = CMBlockBufferGetDataLength(blockBuffer);
-      while (currentStart < size) {
-        char* data = nullptr;
-        size_t length;
-        if (auto error = CMBlockBufferGetDataPointer(blockBuffer, currentStart, &length, nullptr, &data)) {
-          RTC_LOG(LS_ERROR) << "H264 decoder: CMBlockBufferGetDataPointer failed with error " << error;
-          return;
+    buffer->SetSize(0);
+    CMBlockBufferRef blockBuffer = CMSampleBufferGetDataBuffer(sampleBuffer);
+    size_t currentStart = 0;
+    size_t size = CMBlockBufferGetDataLength(blockBuffer);
+    while (currentStart < size) {
+      char* data = nullptr;
+      size_t length;
+      if (auto error = CMBlockBufferGetDataPointer(blockBuffer, currentStart, &length, nullptr, &data)) {
+        RTC_LOG(LS_ERROR) << "H264 decoder: CMBlockBufferGetDataPointer failed with error " << error;
+        return;
+      }
+      buffer->AppendData(data, size);
+      currentStart += size;
+    }
+    if (_descriptionCallback && _needsToSendDescription) {
+      auto formatDescription = CMSampleBufferGetFormatDescription(sampleBuffer);
+      auto sampleExtensionsDict = static_cast<CFDictionaryRef>(CMFormatDescriptionGetExtension(formatDescription, kCMFormatDescriptionExtension_SampleDescriptionExtensionAtoms));
+      if (sampleExtensionsDict) {
+        auto sampleExtensions = static_cast<CFDataRef>(CFDictionaryGetValue(sampleExtensionsDict, CFSTR("avcC")));
+        if (sampleExtensions) {
+          _needsToSendDescription = false;
+          _descriptionCallback(reinterpret_cast<const uint8_t*>(CFDataGetBytePtr(sampleExtensions)), CFDataGetLength(sampleExtensions));
         }
-        buffer->AppendData(data, size);
-        currentStart += size;
       }
-      _descriptionCallback(buffer->data(), buffer->size());
     }
   }
 
@@ -1043,9 +1054,11 @@ - (void)frameWasEncoded:(OSStatus)status
                                                                   RTCVideoContentTypeUnspecified;
   frame.flags = webrtc::VideoSendTiming::kInvalid;
 
-  _h264BitstreamParser.ParseBitstream(*buffer);
-  auto qp = _h264BitstreamParser.GetLastSliceQp();
-  frame.qp = @(qp.value_or(0));
+  if (_useAnnexB) {
+    _h264BitstreamParser.ParseBitstream(*buffer);
+    auto qp = _h264BitstreamParser.GetLastSliceQp();
+    frame.qp = @(qp.value_or(0));
+  }
 
   BOOL res = _callback(frame, codecSpecificInfo, nullptr);
   if (!res) {
@@ -1062,4 +1075,9 @@ - (nullable RTCVideoEncoderQpThresholds *)scalingSettings {
                                                                high:kHighH264QpThreshold];
 }
 
+- (void)flush {
+    if (_vtCompressionSession)
+        VTCompressionSessionCompleteFrames(_vtCompressionSession, kCMTimeInvalid);
+}
+
 @end
diff --git a/.../ThirdParty/libwebrtc/Source/webrtc/sdk/objc/components/video_codec/RTCVideoEncoderH265.h b/.../ThirdParty/libwebrtc/Source/webrtc/sdk/objc/components/video_codec/RTCVideoEncoderH265.h
@@ -21,4 +21,5 @@ __attribute__((objc_runtime_name("WK_RTCVideoEncoderH265")))
 - (instancetype)initWithCodecInfo:(RTCVideoCodecInfo *)codecInfo;
 - (void)setUseAnnexB:(bool)useAnnexB;
 - (void)setDescriptionCallback:(RTCVideoEncoderDescriptionCallback)callback;
+- (void)flush;
 @end