doc/examples: remove unneeded NULL checks

dst_file cannot be NULL

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 68bca03951b36755f46d75a5bcfcbba95ced21c4)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Changelog: add 2.4

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 808db3e68778b77e020aab1b838d32e63a38ae63)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/mjpegenc: the AMV encoder doesnt support yuv422

Fixes Ticket3883

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit b227be34db76541db0269a769dad90c20793353f)

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