All Questions
10
questions
1
vote
0
answers
648
views
What variant of Spline algorithm is used in "spline" parameter from "scale" filter?
FFmpeg has two filters to scale the video: scale and zscale - zscale has spline16 and spline36 parameters (they represent Spline16 and Spline36 variants of the algorithm), scale has spline parameter.
...
- 343
1
vote
0
answers
474
views
ffmpeg scaling with precise edges?
i'd like to extract thumbnails from videos. the problem i'm running into is that the boundaries of the reduced images aren't clear due to edge effects in the scaling algorithm. here is a simple mire ...
- 141
1
vote
1
answer
1k
views
Downscaling VP9 from 4K to 1080p without re-compression
I have a video file that is a 4K upscale of a 1080p video in VP9 (upscaled to 4K to force Youtube to use higher bitrate for the video).
I want to downscale the 4K video file to 1080p while (...
- 113
1
vote
1
answer
887
views
FFmpeg: scaling RGB at 16 bits/channel = inaccurate color output
I'm trying to scale an RGB image in a gamma-correct way, i.e. with a gamma transform before and after the scaler. Because gamma correction at 8 bits/channel creates "banding", I convert the ...
- 71
1
vote
1
answer
6k
views
ffmpeg filter_complex connecting outputs
I do splitscreens with ffmpeg xstack - these get really large after some iterations, so I want to scale them down in the process. But I get the error "Filter scale has an unconnected output"....
- 69
1
vote
1
answer
1k
views
FFmpeg - Is it better to scale mosaic videos at the input or the output?
The (batch) script below produces a mosaic of the nine input videos:
FFMPEG ^
-y -i "v1.mp4" -i "v2.mp4" -i "v3.mp4" -i "v4.mp4" -i "v5.mp4" -i "v6.mp4" -i "v7.mp4" -i "v8.mp4" -i "v9.mp4" ^
-...
- 1,596
5
votes
3
answers
7k
views
"height not divisible by 2" with "min"
Using this command:
ffmpeg -loop 1 -r 1 -i q.jpg -t 5 -pix_fmt yuv420p -vf 'scale=-2:min(1080\,ih)' z.mp4
I get this message:
[libx264 @ 00000000004d0ec0] height not divisible by 2 (954x953)
I can ...
- 1
4
votes
2
answers
4k
views
How can I scale an overlay within an ffmpeg filtercomplex?
I would like to apply a PNG overlay (watermark) to an arbitrary video file using ffmpeg. I would like the video to stay its original size (which I don't know ahead of time), and the PNG to be scaled ...
- 1,338
5
votes
1
answer
2k
views
Upscaling video with different filter on each side
I need scale up video from one DOS game using FFmpeg. But with Nearest-neighbor interpolation on left side and xBR filter on the other one.
Input (320x200)
Output (1280x800)
Here is a command, ...
- 205
1
vote
0
answers
2k
views
Scale (or center) watermark with ffmpeg to same resolution as output file
I want to have the watermark scaled to the same resolution as the output file. How do I do this?
Alternatively, how do I center the watermark in the middle of the output instead?
Here is what I have:
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- 413