Can anyone help me improve this FFMPEG script?

[Guernsey]

Can anyone talk a look at this script? I am to make this setup into a FFMPEG script and even an AVISynth/AVS script. Here is what I am trying to do:

1. Using Virtualdub I was going to do two resizes using Nearest Neighbor and later Lanzcos3. The Nearest Neighbor resize filter was going to upscale the video while the other filter was for aspect ratio correction via "Compute Height from Ratio" on Lanzcos3. I know you do not have to do this in FFMPEG or AVISynth but you could in Virtualdub2.
2. I was to resize it to four times bigger than usual since that is considered HD and I do not want it to be bigger than what it can allowed to be.
3. I was put in a .mp4 video container with .aac as the audio container. Someone recommended me libopus as a possible audio codec but I want to play it safe with .aac.
4. As for codecs and compression, I mostly use x264 8 bit with a Slower compression with the constant rate factor being either 16 or lossless.
5. I wanted colorspace from RGB to YUV. I mostly work with pixels from old video games.

I was wondering how can I do so with this FFMPEG script? Do those options that I have about match what I want do? And if possible, how can export it to AVISynth or AVS.

Here is the script in question:

ffmpeg -i input -vf "scale=iwX:ihX" -sws_flags neighbor -pix_fmt yuv420p -c:v libx264 -preset slower -crf 16 -c:a libopus -b:a 128k

[jagabo]

Your syntax for -vf is all wrong.

-vf "scale=iw*4:ih*4:sws_flags=neighbor,format=yuv420p"

[pandy]

you can even simplify scale syntax further (and force scale to particular behavior):

-vf "scale=iw*4:-2:sws_flags=neighbor+accurate_rnd+full_chroma_int+full_chroma_inp,format=pix_fmts=yuv420p"

If your source is pixel graphic then you may consider to use pixel art dedicated scaler like xBR , hqx , epx or Super2xSaI .

[Guernsey]

Alright I will give those a shot. Is there a way to those on AVISynth so that I can make an AVS script from it?

[poisondeathray]

Is there a way to those on AVISynth so that I can make an AVS script from it?

There are some pixel art resamplers featured in PointSize for avisynth
http://avisynth.nl/index.php/PointSize

[pandy]

Not sure why you are using AVISynth - in case you need real time (depends on you CPU) preview then you may use pipe from ffmpeg to ffplay

ffmpeg.exe -i yourfile -vf yourvideofilter -c:v yourvideocodec -c:a youraudiocodec -vsync 0 -f NUT - | ffplay.exe -hide_banner -loglevel 32 -autoexit -i -

[Guernsey]

Since my laptop is gone, I mostly used FFMPEG. Will that tell me the end result? I also want to trim before a certain time.

[poisondeathray]

I also want to trim before a certain time.

You can use -vf trim to specify frames or times to include (and by extension, exclude)

https://ffmpeg.org/ffmpeg-filters.html#trim

[jagabo]

Or use -ss to start at a specific time.

ffmpeg -i input.ext -ss 00:05:00.000 output.ext

That will skip the first 5 minutes or the source.