ffmpeg - 多次写入同一帧？

Question

使用以下命令:

ffmpeg -i test.mp4 -vf "select='not(mod(n,2000))',setpts=N/3/TB" -r 3 output.gif

我在 3fps GIF 文件中每 2000 帧写入 1 帧。

但是当我查看 ffmpeg 的输出时，有些令人困惑:

speed=0.00997frame=    1 fps=0.7 q=-0.0 size=       1kB time=00:00:00.01
speed=0.00498frame=    1 fps=0.4 q=-0.0 size=       1kB time=00:00:00.01
speed=0.00332frame=    2 fps=0.6 q=-0.0 size=       2kB time=00:00:00.34
speed=0.0847xframe=    2 fps=0.4 q=-0.0 size=       2kB time=00:00:00.34
speed=0.0678xframe=    2 fps=0.4 q=-0.0 size=       2kB time=00:00:00.34
speed=0.0565xframe=    2 fps=0.3 q=-0.0 size=       2kB time=00:00:00.34
speed=0.0968xframe=    3 fps=0.4 q=-0.0 size=      20kB time=00:00:00.68
speed=0.0847xframe=    3 fps=0.4 q=-0.0 size=      20kB time=00:00:00.68
speed=0.0753xframe=    3 fps=0.3 q=-0.0 size=      20kB time=00:00:00.68
speed=0.0678xframe=    4 fps=0.4 q=-0.0 size=      41kB time=00:00:01.01
speed=0.0915xframe=    4 fps=0.3 q=-0.0 size=      41kB time=00:00:01.01
speed=0.0839xframe=    4 fps=0.3 q=-0.0 size=      41kB time=00:00:01.01
speed=0.0774xframe=    4 fps=0.3 q=-0.0 size=      41kB time=00:00:01.01
speed=0.0954xframe=    5 fps=0.3 q=-0.0 size=      66kB time=00:00:01.34
speed=0.089x frame=    5 fps=0.3 q=-0.0 size=      66kB time=00:00:01.34
speed=0.0834xframe=    5 fps=0.3 q=-0.0 size=      66kB time=00:00:01.34
speed=0.0785xframe=    6 fps=0.3 q=-0.0 size=      90kB time=00:00:01.68
speed=0.093x frame=    6 fps=0.3 q=-0.0 size=      90kB time=00:00:01.68
speed=0.0881xframe=    6 fps=0.3 q=-0.0 size=      90kB time=00:00:01.68
speed=0.0837xframe=    6 fps=0.3 q=-0.0 size=      90kB time=00:00:01.68

看起来每个目标帧都被重建了多次。
我会期待这样的事情:

speed=0.00997frame=    1 fps=0.7 q=-0.0 size=       1kB time=00:00:00.01
speed=0.00332frame=    2 fps=0.6 q=-0.0 size=       2kB time=00:00:00.34
speed=0.0968xframe=    3 fps=0.4 q=-0.0 size=      20kB time=00:00:00.68
speed=0.0678xframe=    4 fps=0.4 q=-0.0 size=      41kB time=00:00:01.01
speed=0.0954xframe=    5 fps=0.3 q=-0.0 size=      66kB time=00:00:01.34
speed=0.0785xframe=    6 fps=0.3 q=-0.0 size=      90kB time=00:00:01.68

我错过了什么吗？

(这是 ffmpeg - multiple output with thumbnails 的后续内容)

Answer 1

那只是进度报告。每次刷新报表时，如果新的帧还没有被编码，它将显示相同的数字。 fps 速度为 1.0表示每秒编码 1 帧。因此，如果一秒钟内刷新了两次进度报告，则第二次将显示相同的帧数。