NVEnc Preview

[Dan64]

Hello Selur,

This is a working example of preview using filters. 
It is very useful to have a preview of filtered output.

import vapoursynth as vs
from vapoursynth import core
import subprocess
import ctypes

NVEnc = r'E:\VideoTest\TestSubs\NVEncC64.exe'
source_path=r'E:\VideoTest\TestSubs\TestVideo.mp4'
#Loading Plugins
core.std.LoadPlugin(path="E:/VideoTest/TestSubs/BestSource.dll") #from https://forum.doom9.org/showthread.php?t=184255
#current color space: YUV420P8, bit depth: 8
#resolution: 1280x536, fps: 25, color matrix: 470bg, yuv luminance scale: limited, scanorder: progressive
#this clip is not not needed, just to get width and height
clip = core.bs.VideoSource(source=source_path)

w = clip.width
h = clip.height
bitdepth=8
Ysize  = w * h * bitdepth // 8
Usize = w * h//4 * bitdepth // 8
Vsize = w * h//4 * bitdepth // 8
frame_len = Ysize + Usize + Vsize #YUV420

nvenc_filters = [
'--vpp-pmd apply_count=3,strength=100,threshold=100',
'--vpp-unsharp radius=4,weight=0.5,threshold=10',                 
'--vpp-smooth quality=3,qp=60,prec=fp32',
'--vpp-tweak brightness=0.01,contrast=1.01,gamma=0.98,saturation=0.90,hue=-2,swapuv=false',
'--vpp-deband range=15,sample=1,thre=15,dither=15,seed=1234,blurfirst=off,rand_each_frame=off',
]

command = [NVEnc,
                 '--avhw',
                 '--input "'+source_path+'" '
                 '-c raw',
                 ' '.join(nvenc_filters),
                 '--output-res '+str(w)+'x'+str(h),
                 '--output-csp yuv420',
                 '--output-depth '+str(bitdepth),
                 '--output-format raw',               
                 '--output -',         
             ]
command = ' '.join(command)

pipe = subprocess.Popen(command, stdout = subprocess.PIPE, bufsize=frame_len)

def load_frame_from_pipe(n,f):
    vs_frame = f.copy()   
    try:
        for i, size in enumerate([Ysize, Usize, Vsize]):
            ctypes.memmove(vs_frame.get_write_ptr(i), pipe.stdout.read(size),  size)
        pipe.stdout.flush()
    except Exception as e:
        raise ValueError(repr(e))   
    return vs_frame

try:
    clip = core.std.ModifyFrame(clip, clip, load_frame_from_pipe)
except ValueError as e:
    pipe.terminate()
    print(e)

clip.set_output()

Hybrid has already all the components necessary to build the preview.
What was missing was the script to obtain the preview with Vapoursynth.
Now that we have it, it's a shame not to use it.
 
I hope that you will reconsider the possibility to include this feature in Hybrid.

Thanks,
Dan