问题描述

这是我通过 PHP 运行的向视频添加图像的代码:

exec('ffmpeg -i input.mp4 -i logo.png -filter_complex"[0:v][1:v] overlay=10:10" -pix_fmt yuv420p -c:a copy output.mp4');

它运行良好，但问题是，图像在视频分辨率上被缩小或放大.例如，在以下图像中，徽标宽度为 50px，但视频分辨率不同:

还有这个

如何防止图像缩小/放大?

更新

感谢

还有这个

是否可以改进此解决方案?

您可以使用 scale2ref 过滤器.

ffmpeg -i input.mp4 -i logo.png -filter_complex[1:v][0:v]scale2ref=(W/H)*ih/8/sar:ih/8[wm][base];[base][wm]overlay=10:10"-pix_fmt yuv420p -c:a copy output.mp4

这会将徽标的高度调整为视频高度的 1/8.

您必须将 W/H 替换为图像的值，例如如果 PNG 是 320x270，那么它应该是 scale2ref=(320/270)*ih/8:ih/8

This is my code that adds an image to videos, running via PHP:

exec('ffmpeg -i input.mp4 -i logo.png -filter_complex 
"[0:v][1:v] overlay=10:10"  -pix_fmt yuv420p -c:a copy output.mp4');

It works well but the problem is, the image is scaled down or up, up on the video resolution. For example in the following images the logo width is 50px but videos resolution are different:

and this one

How can I prevent the image from scaling down/up ?

Update

Thanks to Mulvya, he proposed these codes

ffmpeg -i input.mp4 -i logo.png -filter_complex 
"[1:v][0:v]scale2ref=(W/H)*ih/8:ih/8[wm][base];[base][wm]overlay=10:10"
-pix_fmt yuv420p -c:a copy output.mp4

and

ffmpeg -i input.mp4 -i logo.png -filter_complex 
"[1:v][0:v]scale2ref=(W/H)*ih/8:ih/8[wm][base];[wm]setsar=1[wmsar];
[base][wmsar]overlay=10:10"
-pix_fmt yuv420p -c:a copy output.mp4

that works very well, but it doesn't keep the logo aspect ratio. I tried this code on two videos with different resolution and this is the result

and this one

Is it possible to improve this solution?

You can use the scale2ref filter.

ffmpeg -i input.mp4 -i logo.png -filter_complex 
"[1:v][0:v]scale2ref=(W/H)*ih/8/sar:ih/8[wm][base];[base][wm]overlay=10:10"
-pix_fmt yuv420p -c:a copy output.mp4

This will resize the logo's height to 1/8th of the height of the video.

You have to replace W/H with the values for the image e.g. if the PNG is 320x270, then it should be scale2ref=(320/270)*ih/8:ih/8

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