[FFmpeg-user] How can I add a header to an HTTP Post from the command line?

[Tom Sheffler]

A URL may be used as an output file (or output file sequence) and this
works fine for me:

   ffmpeg -i input ...  http://output/path

The source code leads me to believe that certain options (like user-agent)
can be changed from the command line, or that arbitrary HTTP headers can be
added with a "-headers" flag.  I have tried things liks:

  ffmpeg -i input ... http://output/path -user-agent "my-own-agent"

However, I have not been able to figure out how to make command line
options have any effect on HTTP POST output files.

Any help would be appreciated, including information that this is not
supposed to work.  P.S. - I am using version 0.10.2.

Thanks. Tom