[FFmpeg-user] ffmpeg overlay with transparent effect

[qw]

Hi 


>However, the following places a logo on a video:
>$ ffmpeg -i video -loop 1 -i logo -filter_complex 
>overlay -qscale 2 out.avi
>

The command does place a logo on a video. But there is no transparent effect, and I can't the image of vidoe behind the logo.


The basic theory is easy: alpha is used to control the weight of pixel to display in video and logo. The formula is shown below:
final pixel = alpha * video pixel + (1 - alpha) * logo pixel.


But how to make transparent effect by ffmpeg?






At 2015-06-25 18:01:01, "Carl Eugen Hoyos" <cehoyos at ag.or.at> wrote:
>qw <applemax82 <at> 163.com> writes:
>
>> I place a logo image on a video, and overlayed video 
>> should have transparent effect. What's the ffmpeg
>> command to create this kind of video?
>
>Generally, you are expected here to provide the command 
>line that you tried together with the complete, uncut 
>console output and an explanation what went wrong.
>
>However, the following places a logo on a video:
>$ ffmpeg -i video -loop 1 -i logo -filter_complex 
>overlay -qscale 2 out.avi
>
>Carl Eugen
>
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