libswresample: Avoid needlessly large on-stack array.

We only actually need to use a tiny part of it.
Unfortunately we seem to have no real test coverage on
the code, so this is a bit risky.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
Remove pointless if.

A branch to avoid some calculation seems unlikely to have any benefits.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
libswresample: move condition to start of loop.

This avoids several issue like calculating sum/maxcoef
incorrectly due to adding up matrix entries that will
be overwritten, as well as out-of-range writes to
s->matrix if the maximum allowed number of channels is used.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
lavf/segment: add segment_format_options option
doc/muxers/segment: reword text for examples, improve consistency
avcodec/mpegvideo: free_context_frame() cannot fail, make it return void

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/mpegvideo: Use "goto fail" for all error paths in ff_mpv_common_frame_size_change()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/mpegvideo: check that the context is initialized in ff_mpv_common_frame_size_change()

The function otherwise would initialize the context without setting context_initialized
alternatively we could set context_initialized

Fixes valgrind anomalies related to ticket 3928

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