ffmpeg watermark first 30 second

Question

ffmpeg -i v.3gp -acodec copy -vf "movie=w.png [logo]; [in][logo] overlay=10:main_h-overlay_h-10 [out]" nv.3gp

It work's fine, but i want watermark only first 30 seconds. Any ideas?

Answer 1

You can convert the logo into a 30 second video with png codec and alpha channel, and apply the video as overlay.

The duration of the logo video should be specified through the number of frames at the frame rate of the main video (in your case, v.3pg). For example, for 30 fps main video run:

ffmpeg.exe -loop 1 -i w.png -vframes 901 -vf "fade=out:899:1:alpha=1" 
    -vcodec png -pix_fmt rgba w.mov

The logo needs to be faded out; otherwise it will not disappear. Then use the logo video as overlay on another video:

ffmpeg -i v.3gp -acodec copy -vf "movie=w.mov [logo]; [in][logo]
    overlay=10:main_h-overlay_h-10 [out]" nv.3gp

Alternatively, rather then ending abruptly, the logo can be faded out gradually, e.g. within 30 frames using -vf "fade=out:870:30:alpha=1".