Avoid steady-state v210 double copy

MxlSdkFeed.cpp

@@ -518,6 +518,105 @@ const VideoFrame& MxlSdkFeed::getFrame(uint32_t frameCounter)
     return mFrame;
 }
 
+bool MxlSdkFeed::readV210FrameInto(
+    uint32_t frameCounter,
+    void* destination,
+    size_t destinationSize)
+{
+    (void)frameCounter;
+
+    if (!mFlowOpened && !openFlow())
+    {
+        return false;
+    }
+
+    uint64_t index = mLastDisplayedIndex + 1;
+    const uint64_t currentIndex = mxlGetCurrentIndex(&mGrainRate);
+
+    if (index > currentIndex)
+    {
+        return false;
+    }
+
+    mxlGrainInfo grain{};
+    grain.version = 2;
+    grain.size = sizeof(mxlGrainInfo);
+
+    uint8_t* payload = nullptr;
+
+    while (true)
+    {
+        mxlStatus status = mxlFlowReaderGetGrainNonBlocking(
+            mReader,
+            index,
+            &grain,
+            &payload);
+
+        if (status == MXL_STATUS_OK)
+        {
+            break;
+        }
+
+        if (status == MXL_ERR_OUT_OF_RANGE_TOO_EARLY)
+        {
+            return false;
+        }
+
+        if (status == MXL_ERR_OUT_OF_RANGE_TOO_LATE)
+        {
+            mxlFlowRuntimeInfo runtimeInfo{};
+            if (mxlFlowReaderGetRuntimeInfo(mReader, &runtimeInfo) !=
+                MXL_STATUS_OK)
+            {
+                return false;
+            }
+
+            if (runtimeInfo.headIndex == 0)
+            {
+                return false;
+            }
+
+            index = runtimeInfo.headIndex - 1;
+
+            if (index <= mLastDisplayedIndex)
+            {
+                return false;
+            }
+
+            continue;
+        }
+
+        if (status == MXL_ERR_FLOW_INVALID)
+        {
+            std::cerr << "MxlSdkFeed: flow invalidated, reconnecting"
+                      << std::endl;
+            closeFlow();
+            return false;
+        }
+
+        std::cerr << "MxlSdkFeed: grain read error status="
+                  << static_cast<int>(status) << std::endl;
+        return false;
+    }
+
+    const size_t payloadSize =
+        static_cast<size_t>(mSourceStride) *
+        static_cast<size_t>(mSourceHeight);
+
+    if (payload == nullptr ||
+        destination == nullptr ||
+        payloadSize == 0 ||
+        destinationSize < payloadSize)
+    {
+        return false;
+    }
+
+    std::memcpy(destination, payload, payloadSize);
+    mLastDisplayedIndex = index;
+    ++mFrameVersion;
+    return true;
+}
+
 FeedRuntimeStatus MxlSdkFeed::status() const
 {
     if (mFlowOpened && !mV210Payload.empty())
@@ -616,6 +715,7 @@ float MxlSdkFeed::srcAspectRatio() const
 
 bool MxlSdkFeed::hasV210() const { return mFlowOpened && !mV210Payload.empty(); }
 const uint8_t* MxlSdkFeed::v210Data() const { return mV210Payload.data(); }
+bool MxlSdkFeed::supportsDirectV210Read() const { return mFlowOpened; }
 uint32_t MxlSdkFeed::v210Width() const { return mSourceWidth; }
 uint32_t MxlSdkFeed::v210Height() const { return mSourceHeight; }
 uint32_t MxlSdkFeed::v210Stride() const { return mSourceStride; }
@@ -635,6 +735,17 @@ double MxlSdkFeed::frameRate() const { return 0.0; }
 float MxlSdkFeed::srcAspectRatio() const { return 16.0f / 9.0f; }
 bool MxlSdkFeed::hasV210() const { return false; }
 const uint8_t* MxlSdkFeed::v210Data() const { return nullptr; }
+bool MxlSdkFeed::supportsDirectV210Read() const { return false; }
+bool MxlSdkFeed::readV210FrameInto(
+    uint32_t frameCounter,
+    void* destination,
+    size_t destinationSize)
+{
+    (void)frameCounter;
+    (void)destination;
+    (void)destinationSize;
+    return false;
+}
 uint32_t MxlSdkFeed::v210Width() const { return 0; }
 uint32_t MxlSdkFeed::v210Height() const { return 0; }
 uint32_t MxlSdkFeed::v210Stride() const { return 0; }