Fix no PTS and delay for realtime streaming

[calanor]

I need streaming sources to rtmp server and I ned to fix the output PTS and add delay to prevent to send all the data in an instant that its not accepted for the streaming server.

I Used this guide https://titanwolf.org/Network/Articles/Article?AID=3550447c-3b06-4998-a6bf-66b4e57e09b6 and work fine with the simplest FFmpeg-based push streamer code supplied.

How I apply this fixes in 3_transcoding.c example?