[FFmpeg-user] show watermark at the beginning of the video

Paul B Mahol onemda at gmail.com
Tue Mar 19 11:52:43 CET 2013


On 3/19/13, Alex Vasilenko <aa.vasilenko at gmail.com> wrote:
>> On 3/19/13, Alex Vasilenko <aa.vasilenko at gmail.com
>> (mailto:aa.vasilenko at gmail.com)> wrote:
>> > Hi all ,
>> >
>> > Need to add watermark for first 3 seconds the video using ffmpeg.
>> > Here's
>> > what I got right now:
>> >
>> > ffmpeg -y -i '255871.mov' -qscale:v 0 -qscale:a 0 -vf '[in] transpose=1
>> > [out];movie=watermark.png , select=lte(t\,3) [bg]; [out][bg]
>> > overlay=x=20:y=main_h-60 [out]' output.mp4
>> >
>> > It rotates video to the right and adds watermark at the bottom of the
>> > video
>> > for first 3 seconds. The problem is watermark is visible during the
>> > whole
>> > video.
>> >
>> > Thought that select doesn't work at all. Tried following command
>> >
>> > ffmpeg -y -i '255871.mov' -qscale:v 0 -qscale:a 0 -vf '[in] transpose=1
>> > [out];movie=watermark.png , select=0 [bg]; [out][bg]
>> > overlay=x=20:y=main_h-60 [out]' output.mp4
>> >
>>
>>
>> watermark.png is single frame, so select always pick it,
>> yes it it little strange but that is how overlay filter works.
>>
>> Instead you could use blend filter, you first would need to pad
>> watermark.png
>> with pad filter to same size as input and pad it with black color and than
>> set
>> some complicated expression for blend filter.
>>
>>
>
> Wow, that's far more complicated. But how does select filter work? Shouldn't
> it filter out watermark frame after 3 seconds of video?

't' is presentation timestamp for watermark, which may never by higher than 3
as it is single frame. You could instead replace 't' with 'n'.

>>
>> This is too much complicated and IIRC there is ongoing work on making
>> real scripting
>> with libavfilter available.
>>
>>
>
> Good news! :)
>>
>> >
>> > Watermark is not visible. This is correct and proves that select filter
>> > works as expected. As I understand this is how ffmpeg works: it leaves
>> > last
>> > frame of the shortest video visible.
>> >
>> > How can I force ffmpeg to discard show watermark after N seconds?
>> >
>> > Cross posted this question on SO:
>> > http://stackoverflow.com/questions/15482644/show-watermark-at-the-beginning-of-the-video
>> >
>> >
>> > Thanks,
>> > --
>> > Alex Vasilenko
>> >
>> > _______________________________________________
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>> > ffmpeg-user at ffmpeg.org (mailto:ffmpeg-user at ffmpeg.org)
>> > http://ffmpeg.org/mailman/listinfo/ffmpeg-user
>> >
>>
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