RMTP stream error using libavformat/avcodec

Hi guys,

I'm writing a small program to stream video from usb camera to wowza server.

The libraries that I used are: libavformat, libavcodec like this question:
https://stackoverflow.com/questions/48578088/streaming-flv-to-rtmp-with-ffmpeg-using-h264-codec-and-c-api-to-flv-js

I use opencv to access camera and get the frame then stream it to wowza.
When I test it on web browser, there are two line across the frame like this:
https://cl.ly/310G0i423B0b

If I use imshow in opencv to see the picture, everything is fine.
Please help and tell me if you need further information.

Best regards,
Duong Hieu MAI