feat(nvenc): implement async encode

src/nvenc/nvenc_base.cpp

@@ -528,7 +528,7 @@
 
     NV_ENC_LOCK_BITSTREAM lock_bitstream = {min_struct_version(NV_ENC_LOCK_BITSTREAM_VER, 1, 2)};
     lock_bitstream.outputBitstream = output_bitstream;
-    lock_bitstream.doNotWait = 0;
+    lock_bitstream.doNotWait = async_event_handle ? 1 : 0;
 
     if (async_event_handle && !wait_for_async_event(100)) {
       BOOST_LOG(error) << "NvEnc: frame " << frame_index << " encode wait timeout";

src/nvenc/nvenc_d3d11.cpp

@@ -10,11 +10,19 @@
 
 namespace nvenc {
 
+  nvenc_d3d11::nvenc_d3d11(NV_ENC_DEVICE_TYPE device_type):
+      nvenc_base(device_type) {
+    async_event_handle = CreateEvent(NULL, FALSE, FALSE, NULL);
+  }
+
   nvenc_d3d11::~nvenc_d3d11() {
     if (dll) {
       FreeLibrary(dll);
       dll = NULL;
     }
+    if (async_event_handle) {
+      CloseHandle(async_event_handle);
+    }
   }
 
   bool nvenc_d3d11::init_library() {
@@ -53,5 +61,9 @@
     return false;
   }
 
+  bool nvenc_d3d11::wait_for_async_event(uint32_t timeout_ms) {
+    return WaitForSingleObject(async_event_handle, timeout_ms) == WAIT_OBJECT_0;
+  }
+
 }  // namespace nvenc
 #endif

src/nvenc/nvenc_d3d11.h

@@ -25,10 +25,7 @@ namespace nvenc {
    */
   class nvenc_d3d11: public nvenc_base {
   public:
-    explicit nvenc_d3d11(NV_ENC_DEVICE_TYPE device_type):
-        nvenc_base(device_type) {
-    }
-
+    explicit nvenc_d3d11(NV_ENC_DEVICE_TYPE device_type);
     ~nvenc_d3d11();
 
     /**
@@ -39,6 +36,7 @@ namespace nvenc {
 
   protected:
     bool init_library() override;
+    bool wait_for_async_event(uint32_t timeout_ms) override;
 
   private:
     HMODULE dll = NULL;

src/video.cpp

@@ -299,6 +299,7 @@ namespace video {
     REF_FRAMES_INVALIDATION = 1 << 8,  ///< Support reference frames invalidation
     ALWAYS_REPROBE = 1 << 9,  ///< This is an encoder of last resort and we want to aggressively probe for a better one
     YUV444_SUPPORT = 1 << 10,  ///< Encoder may support 4:4:4 chroma sampling depending on hardware
+    ASYNC_TEARDOWN = 1 << 11,  ///< Encoder supports async teardown on a different thread
   };
 
   class avcodec_encode_session_t: public encode_session_t {
@@ -503,7 +504,7 @@ namespace video {
       {},  // Fallback options
       "h264_nvenc"s,
     },
-    PARALLEL_ENCODING | REF_FRAMES_INVALIDATION | YUV444_SUPPORT  // flags
+    PARALLEL_ENCODING | REF_FRAMES_INVALIDATION | YUV444_SUPPORT | ASYNC_TEARDOWN  // flags
   };
 #elif !defined(__APPLE__)
   encoder_t nvenc {
@@ -1856,6 +1857,23 @@ namespace video {
       return;
     }
 
+    // As a workaround for NVENC hangs and to generally speed up encoder reinit,
+    // we will complete the encoder teardown in a separate thread if supported.
+    // This will move expensive processing off the encoder thread to allow us
+    // to restart encoding as soon as possible. For cases where the NVENC driver
+    // hang occurs, this thread may probably never exit, but it will allow
+    // streaming to continue without requiring a full restart of Sunshine.
+    auto fail_guard = util::fail_guard([&encoder, &session] {
+      if (encoder.flags & ASYNC_TEARDOWN) {
+        std::thread encoder_teardown_thread {[session = std::move(session)]() mutable {
+          BOOST_LOG(info) << "Starting async encoder teardown";
+          session.reset();
+          BOOST_LOG(info) << "Async encoder teardown complete";
+        }};
+        encoder_teardown_thread.detach();
+      }
+    });
+
     // set minimum frame time, avoiding violation of client-requested target framerate
     auto minimum_frame_time = std::chrono::milliseconds(1000 / std::min(config.framerate, (config::video.min_fps_factor * 10)));
     BOOST_LOG(debug) << "Minimum frame time set to "sv << minimum_frame_time.count() << "ms, based on min fps factor of "sv << config::video.min_fps_factor << "."sv;