[FFmpeg-user] how to blend logo and video with transparent effect

[Paul B Mahol]

On 6/27/15, qw <applemax82 at 163.com> wrote:
> At 2015-06-27 00:21:56, "Paul B Mahol" <onemda at gmail.com> wrote:
>>On 6/26/15, Paul B Mahol <onemda at gmail.com> wrote:
>>> On 6/26/15, qw <applemax82 at 163.com> wrote:
>>>> Hi,
>>>>
>>>> I use the below command to blend logo image and video together with
>>>> transparent effect:
>>>> ffmpeg -i ./file1.mp4 -i ./logo.jpg -filter_complex
>>>> blend=all_mode=overlay
>>>> ./file3.mp4
>>>>
>>>>
>>>>
>>>> But the command requires the same resolution from logo image and video.
>>>> If
>>>> the size of logo image is different from or smaller than that of video,
>>>> the
>>>> command will report error.
>>>>
>>>>
>>>> How to blend image and video with different size? Could you provide
>>>> some
>>>> command examples?
>>>
>>> You could crop logo and use expressions in blend filter to pick right
>>
>>Instead of crop I meant pad filter.
>>
>>> combination of pixels at any position of image.
>
>
> I try to use pad filter. If the logo image has no transparent background, I
> can make a video with transparent effect by using the below command:
> ffmpeg -i ./video.mp4 -i ./logo.png -filter_complex
> "[1]pad=640:480:10:10:black[logo];[0][logo]blend=all_expr='A*(if(gte(X,10)*lt(X,256+10)*gte(Y,10)*lt(Y,256+10),0.5,1))+B*(1-(if(gte(X,10)*lt(X,256+10)*gte(Y,10)*lt(Y,256+10),0.5,1)))'"
> -strict -2 ./output.mp4
> But if the background in the logo image is transparent, the resulting video
> is not good. I can see a clear rectangle around the logo in the resulting
> video. If the area around logo in resulting video is the pixel of input
> video, and no rectangle can be seen, the resulting video will be correct.
>
>
> How to make a resulting video with a transparent logo image, in which:
> 1) the area around logo is  the pixel of input video;
> 2) no rectangle around the logo can be seen;
> 3) the logo is transparent;
>
>
> How to make it?

Can you provide link to logo.png ?