Add watermark( image file ) for video, JPG is OK, PNG is no useful~

[kangle1208]

Excuse me I use the ffmpeg-android library，on the Android Phone, is All Right!

But, I build ffmpeg by myself, and use it on iPhone，JPG is OK，PNG is no useful~~ And the log show : Generic error in an external library

I use "ffmpeg -codecs" command to view: DEV..S apng APNG (Animated Portable Network Graphics) image DEV..S png PNG (Portable Network Graphics) image DEVI.S zlib LCL (LossLess Codec Library) ZLIB All the decoder is exist

The log : Generic error in an external library Is the library means libpng?

I have install libpng on my MAC If use png file to make watermark, is the libpng must be build into ffmpeg？

I see some info in ffmpeg_build.sh --extra-libs="-lpng -lexpat -lm" Is it means include libpng library?

Thank you!