Question

我想用ffmpeg改变我的视频分辨率：

-s 852×480

如果视频宽度或高度大于852×480，我该怎么办？

我想用 ffmpeg 这样的东西，而不是我的编程语言：

if video.width > 852:
   resize width and proportionally resize height

if video.height > 480:
   resize height and proportionally resize width

if video.width > 852 and video.height > 480:
   resize height width

Answer 1

@LordNeckbeard给了我一个链接https://superuser.com/questions/566998/how-can-i-fit-a-video-to-a-certain-size-but-dont-upscale-it-with-ffmpeg/567934#567934 - 但它确实是一个混乱的解决方案。

所以我只是用python做了：

maximal_width = 852.0
maximal_height = 480.0
if width > maximal_width and height > maximal_height:
    args += ['-vf', 'scale=%s:%s' % (maximal_width, maximal_height)]
else:
    if width > maximal_width:
        coefficient = width / maximal_width
        calculated_height = height / coefficient
        args += ['-vf', 'scale=%s:%s' % (maximal_width, calculated_height)]

    if height > maximal_height:
        coefficient = height / maximal_height
        calculated_width = width / coefficient
        args += ['-vf', 'scale=%s:%s' % (calculated_width, maximal_height)]

Answer 2

在命令中使用此过滤器：

-filter_complex "scale=if(gt(iw,852),852,-1)':'if(gt(ih,480),480,-1)':force_original_aspect_ratio=decrease"

ffmpeg按条件更改分辨率

2 个答案: