Merge commit '3e265ca5'

* commit '3e265ca5':
  avconv: do packet ts rescaling in write_packet()

This commit is a noop since it doesn't apply cleanly due to differences
in the dataflow between avconv and ffmpeg, and thus fixing this in the
scope of a merge is unfeasible.
Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>