Input transparent pipe:0 motions into FFMPEG

[ntphcm]

I followed this to bring a stdinput into FFMPEG.

The idea is: we use AS3 to capture every frame in Animate to byteArray (with ARGB pixel format - means the frame can have transparancy background). After that, we transfer that byteArray into FFMPEG to get output.

If I capture a non-transparency picture motion (the picture with background), the process works well to create a motion video.

But when I capture transparency pictures and make motion (multi-frame video), the problem appears as below:

[Attachment 61039 - Click to enlarge]

We can see the bird print a long streak, but I expect one bird flying from the right to the left like this.

[Attachment 61040 - Click to enlarge]

It seems like the previous frames are not cleared.

Do you have any suggestions to solve this?