如何使用ffmpeg在视频的每个帧上显示帧号？ [英] How to display a frame number on each frame of a video using ffmpeg?

问题描述

我的测试命令如下：

ffmpeg -i in.mov -vf "drawtext=fontfile=/usr/share/fonts/ttf-bitstream-vera/Vera.ttf: x=(w-tw)/2: y=h-(2*lh)-n: fontcolor=white: fontsize=40: box=1: boxcolor=0x00000000@1: text=" -an -y out.mov

我想显示每帧上的帧号。然而，将文本变量设置为n并没有帮助（它显示n），并且％n似乎是新的行符号。最令我困惑的是这部分

I want to display the frame number on each frame. However, setting the "text" variable to "n" does not help (it displays n) and %n seems to be the new line symbol. The thing that confuses me most is that this part

y=h-(2*lh)-n

效果很好，意味着它获取当前框架的正确值，并相应地移动文本。

works well, meaning it gets the right value of the current frame and moves the text up accordingly.

推荐答案

好的，这个功能不在 ffmpeg 中，但现在是。这是你如何做的：

Ok, this feature was not there in ffmpeg, but now it is. And this is how you do it:

...drawtext=text=%{n}:expansion=normal:fontfile=/usr/share/fonts/ttf-bitstream-vera/Vera.ttf:other_options...

请注意，扩展应设置为正常，现在不是默认值，但应在将来默认（根据ffmpeg文档）。

Note that expansion should be set to normal, which is not the default now, but should be default in the future (according to the ffmpeg documentation).

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