avcodec/mpegvideo_enc: return proper error instead of failing assertion when max rate is not set

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/options_table: add liberal limits to intra dc precission

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/mpegvideo_enc: workaround applications specifying intra dc level based on 8 and othes based on 0bit

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/mpegvideo_enc: check intra dc precission

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/mpegvideo_enc: make edge for interlaced mpeg2 encoding smaller

Fixes segfault
the size can probably be reduced further for the mpeg2 case

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