Remove hard dep on nvcuvid.so and fallback to CPU if it is not available. (#996)

Author: NicolasHug

src/torchcodec/_core/BetaCudaDeviceInterface.cpp

@@ -15,7 +15,7 @@
 #include "src/torchcodec/_core/FFMPEGCommon.h"
 #include "src/torchcodec/_core/NVDECCache.h"
 
-// #include <cuda_runtime.h> // For cudaStreamSynchronize
+#include "src/torchcodec/_core/NVCUVIDRuntimeLoader.h"
 #include "src/torchcodec/_core/nvcuvid_include/cuviddec.h"
 #include "src/torchcodec/_core/nvcuvid_include/nvcuvid.h"
 
@@ -155,6 +155,7 @@ std::optional<cudaVideoCodec> validateCodecSupport(AVCodecID codecId) {
 bool nativeNVDECSupport(const SharedAVCodecContext& codecContext) {
   // Return true iff the input video stream is supported by our NVDEC
   // implementation.
+
   auto codecType = validateCodecSupport(codecContext->codec_id);
   if (!codecType.has_value()) {
     return false;
@@ -222,6 +223,8 @@ BetaCudaDeviceInterface::BetaCudaDeviceInterface(const torch::Device& device)
 
   initializeCudaContextWithPytorch(device_);
   nppCtx_ = getNppStreamContext(device_);
+
+  nvcuvidAvailable_ = loadNVCUVIDLibrary();
 }
 
 BetaCudaDeviceInterface::~BetaCudaDeviceInterface() {
@@ -249,7 +252,7 @@ void BetaCudaDeviceInterface::initialize(
     const AVStream* avStream,
     const UniqueDecodingAVFormatContext& avFormatCtx,
     [[maybe_unused]] const SharedAVCodecContext& codecContext) {
-  if (!nativeNVDECSupport(codecContext)) {
+  if (!nvcuvidAvailable_ || !nativeNVDECSupport(codecContext)) {
     cpuFallback_ = createDeviceInterface(torch::kCPU);
     TORCH_CHECK(
         cpuFallback_ != nullptr, "Failed to create CPU device interface");
@@ -700,8 +703,16 @@ void BetaCudaDeviceInterface::convertAVFrameToFrameOutput(
 }
 
 std::string BetaCudaDeviceInterface::getDetails() {
-  return std::string("Beta CUDA Device Interface. Using ") +
-      (cpuFallback_ ? "CPU fallback." : "NVDEC.");
+  std::string details = "Beta CUDA Device Interface.";
+  if (cpuFallback_) {
+    details += " Using CPU fallback.";
+    if (!nvcuvidAvailable_) {
+      details += " NVCUVID not available!";
+    }
+  } else {
+    details += " Using NVDEC.";
+  }
+  return details;
 }
 
 } // namespace facebook::torchcodec

src/torchcodec/_core/BetaCudaDeviceInterface.h

@@ -98,6 +98,7 @@ class BetaCudaDeviceInterface : public DeviceInterface {
   UniqueNppContext nppCtx_;
 
   std::unique_ptr<DeviceInterface> cpuFallback_;
+  bool nvcuvidAvailable_ = false;
 };
 
 } // namespace facebook::torchcodec

src/torchcodec/_core/CMakeLists.txt

@@ -99,7 +99,7 @@ function(make_torchcodec_libraries
     )
 
     if(ENABLE_CUDA)
-	    list(APPEND core_sources CudaDeviceInterface.cpp BetaCudaDeviceInterface.cpp NVDECCache.cpp CUDACommon.cpp)
+	    list(APPEND core_sources CudaDeviceInterface.cpp BetaCudaDeviceInterface.cpp NVDECCache.cpp CUDACommon.cpp NVCUVIDRuntimeLoader.cpp)
     endif()
 
     set(core_library_dependencies
@@ -108,27 +108,9 @@ function(make_torchcodec_libraries
     )
 
     if(ENABLE_CUDA)
-        # Try to find NVCUVID. Try the normal way first. This should work locally.
-        find_library(NVCUVID_LIBRARY NAMES nvcuvid)
-        # If not found, try with version suffix, or hardcoded path. Appears
-        # to be necessary on the CI.
-        if(NOT NVCUVID_LIBRARY)
-            find_library(NVCUVID_LIBRARY NAMES nvcuvid.1 PATHS /usr/lib64 /usr/lib)
-        endif()
-        if(NOT NVCUVID_LIBRARY)
-            set(NVCUVID_LIBRARY "/usr/lib64/libnvcuvid.so.1")
-        endif()
-
-        if(NVCUVID_LIBRARY)
-            message(STATUS "Found NVCUVID: ${NVCUVID_LIBRARY}")
-        else()
-            message(FATAL_ERROR "Could not find NVCUVID library")
-        endif()
-
         list(APPEND core_library_dependencies
             ${CUDA_nppi_LIBRARY}
             ${CUDA_nppicc_LIBRARY}
-            ${NVCUVID_LIBRARY}
         )
     endif()