UltraGrid plugin: implement stereo mode for GPU

client/ultragrid/ultragrid.cpp

@@ -373,8 +373,16 @@ bool copy_data(struct cesnet_shm *cesnet_shm,
     char *out2_u = out2_y + width * height;
     char *out2_v = out2_u + width * height / 4;
     if (cesnet_shm->use_gpu) {
-      fprintf(stderr, "Stereo mode not yet implemented with the GPU version.\n");
-      return false;
+#  ifdef WITH_CLIENT_CUDA
+      CUDA_CHECK(cudaMemcpy2D(out1_y, width, y, 2 * width, width, height, cudaMemcpyHostToDevice));
+      CUDA_CHECK(cudaMemcpy2D(out2_y, width, y + width, 2 * width, width, height, cudaMemcpyHostToDevice));
+      CUDA_CHECK(cudaMemcpy2D(out1_u, width / 2, u, width, width / 2, height / 2, cudaMemcpyHostToDevice));
+      CUDA_CHECK(cudaMemcpy2D(out2_u, width / 2, u + width / 2, width, width / 2, height / 2, cudaMemcpyHostToDevice));
+      CUDA_CHECK(cudaMemcpy2D(out1_v, width / 2, v, width, width / 2, height / 2, cudaMemcpyHostToDevice));
+      CUDA_CHECK(cudaMemcpy2D(out2_v, width / 2, v + width / 2, width, width / 2, height / 2, cudaMemcpyHostToDevice));
+
+      CUDA_CHECK(cudaIpcCloseMemHandle(out));
+#   endif
     } else {
       // Y
       for (int i = 0; i < height; ++i) {