And when I published stream with video codec H.264, I can get thumbnail via this link
http://[my ip]:8086/thumbnail?application=live&streamname=sss&size=640x640&fitmode=letterbox&format=png
But when published stream with video codec VP8, I cannot get the thumbnail.
Please help me to check about this. Why VP8 can not get thumbnail.
As you see in the name of the module, this is transcoding functionality.
So you need to transcode the WebRTC codec in something that can be read by the module.
If you transcode your WebRTC stream to h264 it will/should work.
I am having issue capturing thumbnails for non transcoded, video codec h264. I am following steps mentioned in https://www.wowza.com/docs/how-to-generate-thumbnail-images-of-live-streams. The transcoded stream from mpeg4 to h264 works for capturing thumbnails.
Any response would greatly appreciated!