[FFmpeg-user] Video file often not recognised

[Cecil Westerhof]

Lately I am doing a lot with ffmpeg again.
But I have a strange problem.
Sometimes I send mp4 through WhatsApp.
Sometimes I see the thumbnail, sometimes I do not.
Today WhatsApp thinks my mp4 is not a video.
So I send it as an ordinary file.
On some places it can be played fine.
On another it plays only audio.
And another it cannot be played.

What can be happening here?
And could I do something about it by changing the parameters I use for
ffmpeg?

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof