ffmpeg with nvenc

Has anyone had success with encoding using NVENC? ffmpeg-3.3.4-1.fc26.x86_64 GeForce 750 Ti When I try: $ ffmpeg -i video.mkv -c:v h264_nvenc -profile:v high -c:a copy -v:profile trace test.mkv [snip] Loaded lib: libcuda.so.1 Loaded sym: cuInit Loaded sym: cuDeviceGetCount Loaded sym: cuDeviceGet Loaded sym: cuDeviceGetName Loaded sym: cuDeviceComputeCapability Loaded sym: cuCtxCreate_v2 Loaded sym: cuCtxPushCurrent_v2 Loaded sym: cuCtxPopCurrent_v2 Loaded sym: cuCtxDestroy_v2 Loaded sym: cuMemAlloc_v2 Loaded sym: cuMemFree_v2 Loaded sym: cuMemcpy2D_v2 Loaded sym: cuGetErrorName Loaded sym: cuGetErrorString Loaded lib: libnvidia-encode.so.1 Loaded sym: NvEncodeAPICreateInstance Loaded sym: NvEncodeAPIGetMaxSupportedVersion [h264_nvenc @ 0x558e5d4b7a80] Loaded Nvenc version 8.0 [h264_nvenc @ 0x558e5d4b7a80] Nvenc initialized successfully [h264_nvenc @ 0x558e5d4b7a80] Cannot init CUDA [h264_nvenc @ 0x558e5d4b7a80] Nvenc unloaded Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height [AVIOContext @ 0x558e5d4b6bc0] Statistics: 0 seeks, 0 writeouts [AVIOContext @ 0x558e5d4badc0] Statistics: 98304 bytes read, 0 seeks Conversion failed!