avformat/mxfenc: instance number is just 24 bits

Fixes assertion failure

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/mpegenc: fix muxrates AVOption maximum value

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/mpegenc: check, warn and clip VBV value to within syntactically possible values

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/mpegenc: check, warn and clip muxrate to syntactical possible values

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>