Webm VP9: Only few frames get converted

I have Webm video generated using webRTC. While converting process got completed immediately without progress bar reaching 100%. Output video length is 1 sec.
If i replace audio in transcoder full video get converted but in output same 1 sec is playing and frame freezes for remaining duration.

I have attached source file, please check it
[Webm VP9 Video.zip](https://github.com/natario1/Transcoder/files/4437038/Webm.VP9.Video.zip)

I have tried many Webm codec VP8, VP9, H264, etc ...

Few thing i have noticed are
1. it works in emulator but when i run in my phone (Android 9) it does not work
2. In Android 10, Webm file is not visible in file picker so cannot select the video.

Please help me, i need to complete this project in 2 days.