I'm trying to actually programmatically add PNG overlay over h264 video.
Even though PNG image has alpha channel, after I apply filter, on a resulting video this image has black background instead of transparent one. Here's the filter:
I'm using openh264 to decode/encode video, so the pixel format of resulting video is YUV420P. I've tried to explicitly define format in filter:
But no change. ffmpeg: 3.4; openh264: Git (i.e. 1.9.0)
Thanks in advance.
Added: My PNG file: may be invisible on white background