Almost the same speed as "direct"
Code:
ffmpeg.exe -i 1.avs -c:v libx265 -preset ultrafast -x265-params ctu=32:pools=10:frame-threads=2 -f rawvideo - > x265.txt 2>&1
ffmpeg version 7211e1c Copyright (c) 2000-2019 the FFmpeg developers
built with gcc 9.1.1 (GCC) 20190517
configuration: --enable-libx265 --enable-avisynth --extra-cflags='-march=core-avx2 -mtune=native -pipe -s -O2' --cpu=core-avx2 --disable-debug --enable-gpl --cross-prefix=x86_64-w64-mingw32- --target-os=mingw32 --arch=x86_64 --pkg-config-flags=--static --enable-zlib --disable-pthreads --enable-w32threads --enable-version3
libavutil 56. 22.100 / 56. 22.100
libavcodec 58. 35.100 / 58. 35.100
libavformat 58. 20.100 / 58. 20.100
libavdevice 58. 5.100 / 58. 5.100
libavfilter 7. 40.101 / 7. 40.101
libswscale 5. 3.100 / 5. 3.100
libswresample 3. 3.100 / 3. 3.100
libpostproc 55. 3.100 / 55. 3.100
Input #0, avisynth, from '1.avs':
Duration: 00:03:00.01, start: 0.000000, bitrate: 0 kb/s
Stream #0:0: Video: rawvideo (Y3[11][10] / 0xA0B3359), yuv420p10le, 1920x1080, 23.98 fps, 23.98 tbr, 23.98 tbn, 23.98 tbc
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo (native) -> hevc (libx265))
Press [q] to stop, [?] for help
x265 [info]: HEVC encoder version 3.0_Au+25-39b35ea86283
x265 [info]: build info [Windows][GCC 9.1.1][64 bit] 10bit
x265 [info]: using cpu capabilities: MMX2 SSE2Fast LZCNT SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
Output #0, rawvideo, to 'pipe:':
Metadata:
encoder : Lavf58.20.100
Stream #0:0: Video: hevc (libx265), yuv420p10le, 1920x1080, q=2-31, 23.98 fps, 23.98 tbn, 23.98 tbc
Metadata:
encoder : Lavc58.35.100 libx265
encoded 4316 frames in 52.01s (82.98 fps), 313.44 kb/s, Avg QP:34.64