ffmpeg nvidia hwaccel yuv444p raw frame output - ffmpeg

Question

I use ffmpeg to do frame decimation, millions of video
I have to use nvidia gpu card (tesla P4) to optimize performance
my ffmpeg command is
ffmpeg -hwaccel cuvid -c:v h264_cuvid -i ./a.mp4 -c:v nvenc -vf "scale_npp=format=yuv444p" -r 1 ./\%08d.raw
but the output data format is weird, I don't know what the format is and how to decode it
I want to know how to decode these data or how to output ream rawdata, can anybody help me?
Log:
built with gcc 8.2.0 (GCC)
configuration: --cc=/opt/compiler/gcc-8.2/bin/gcc --disable-x86asm --enable-cuda --enable-cuvid --enable-nvenc --enable-nvdec --enable-nonfree --enable-libnpp --enable-libx264 --enable-gpl --enable-debug=3 --disable-optimizations --disable-stripping --extra-cflags='-I/home/work/cuda-10.0/include -g3' --extra-ldflags=-L/home/work/cuda-10.0/lib64 --prefix=/home/work/ffmpeg
libavutil 56. 36.101 / 56. 36.101
libavcodec 58. 65.100 / 58. 65.10
libavformat 58. 35.101 / 58. 35.101
libavdevice 58. 9.101 / 58. 9.101
libavfilter 7. 69.101 / 7. 69.101
libswscale 5. 6.100 / 5. 6.100
libswresample 3. 6.100 / 3. 6.100
libpostproc 55. 6.100 / 55. 6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from './a.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf57.71.100
Duration: 00:50:41.28, start: 0.000000, bitrate: 862 kb/s
Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360 >[SAR 1:1 DAR 16:9], 825 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc (default)
Metadata:
handler_name : VideoHandler
Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 29 kb/s (default)
Metadata:
handler_name : SoundHandler
Stream mapping:
Stream #0:0 -> #0:0 (h264 (h264_cuvid) -> h264 (nvenc))
Stream #0:1 -> #1:0 (aac (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #1, wav, to './audio.wav':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
ISFT : Lavf58.35.101
Stream #1:0(eng): Audio: pcm_s16le ([1][0][0][0] / 0x0001), 16000 Hz, mono, s16, 256 kb/s (default)
Metadata:
handler_name : SoundHandler
encoder : Lavc58.65.100 pcm_s16le
[nvenc # 0x44bbc40] This encoder is deprecated, use 'h264_nvenc' instead
Output #0, image2, to './%08d.raw':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.35.101
Stream #0:0(eng): Video: h264 (nvenc) (High 4:4:4 Predictive), cuda, 640x360 [SAR 1:1 DAR 16:9], q=-1--1, 2000 kb/s, 1 fps, 1 tbn, 1 tbc (default)
Metadata:
handler_name : VideoHandler
encoder : Lavc58.65.100 nvenc
Side data:
cpb: bitrate max/min/avg: 0/0/2000000 buffer size: 4000000 vbv_delay: N/A
frame= 3043 fps= 52 q=4.0 Lsize=N/A time=00:50:43.00 bitrate=N/A dup=0 drop=72984 speed=52.3x
video:245435kB audio:6250kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown