I want to resize an image with libavfilter C API through zscale filter and libplacebo filter but no matter how I call av_buffersink_get_frame, it always returns EAGAIN and no data is filled in the filtered_frame.

i’m receiving input as raw H264 NAL units contiguously from one port and mp2 audio from the another port .i need to multiplex this both and encode as a mpeg2 transport stream. To achieve this now i’m executing required ffmpeg command as a process inside my c++ project and i get the output perfectly. but, the problem is i can’t install ffmpeg in client system manually and i felt just for this single purpose using ffmpeg takes more cpu utilization also and handling external process also bit not reliable.