lzwenc: check for negative index

CC: libav-stable@libav.org
Bug-Id: CID 1240206
4xm: more thorought check for negative index and negative shift

CC: libav-stable@libav.org
Bug-Id: CID 1087094
vf_showinfo: check negative index

CC: libav-stable@libav.org
Bug-Id: CID 1087086
mtv: improve header check and avoid division by zero

CC: libav-stable@libav.org
Bug-Id: CID 732203 / CID 732204
shorten: check for return value

Avoid a possible negative bitshift.

CC: libav-stable@libav.org
Bug-Id: CID 1194400
avconv: avoid a null pointer dereference

CC: libav-stable@libav.org
Bug-Id: CID 739877
aviobuf: check context before using it

Avoid a possible null pointer dereference.

CC: libav-stable@libav.org
Bug-Id: CID 1135769
avconv: avoid a possible null pointer dereference

Triggered by the goto handle_eof call.

CC: libav-stable@libav.org
Bug-Id: CID 1238803
vf_format: avoid null pointer dereference

CC: libav-stable@libav.org
Bug-Id: CID 1224280
avconv: avoid null pointer dereference

CC: libav-stable@libav.org
Bug-Id: CID 1087081
dvbsubdec: improve error checking

Use av_mallocz_array instead of iterating and check the returned memory.
Check returned memory and cleanly exit in case of error during the loop.
Avoid a null pointer dereference for invalid data.

CC: libav-stable@libav.org
Bug-Id: CID 29575
network: check return value

ff_socket_nonblock wraps fcntl.

CC: libav-stable@libav.org
Bug-Id: CID 1026742 / CID 1026743 /CID 1026744
mpegvideo: check mpv return value

CC: libav-stable@libav.org
Bug-Id: CID 1238786
avconv: check return value

CC: libav-stable@libav.org
Bug-Id: CID 1224275
escape124: explicitly set get_bits1 variable

Makes coverity less confused.

CC: libav-stable@libav.org
Bug-Id: CID 1203487
indeo3: check ff_set_dimensions return value

CC: libav-stable@libav.org
Bug-Id: CID 1135740
mpegvideo_parser: check ff_set_dimensions return value

Also correctly propagate errors to mpegvideo_parse.

CC: libav-stable@libav.org
Bug-Id: CID 1135741
g2meet: check ff_set_dimensions return value

CC: libav-stable@libav.org
Bug-Id: CID 1135739
avs: check ff_set_dimensions return value

CC: libav-stable@libav.org
Bug-Id: CID 1135738
ansi: check ff_set_dimensions return value

CC: libav-stable@libav.org
Bug-Id: CID 1135737