VBV delay is useful for T-STD compliance in some TS muxers. It is
certainly possible to retrieve it by parsing the output of FFmpeg, but
getting it from the context makes it simpler and less error-prone.
Signed-off-by: Mans Rullgard <mans@mansr.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>