avcodec/jacosubdec: check strftime return value

Fixes CID1257004
avdevice/xcbgrab: Fix show_region rectangle

Fixes trac ticket #4164

This is to address an error when using show_region, which would cause part of the captured area to become static.
It looks like the rectangle specifying the capture area was relative to the capture window.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/utils: Check AVFrame width/height in avcodec_encode_video2()

This is similar to the format check

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/dashenc: make durations 64bit

Fix potential integer overflow
Fix CID1254944

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
doc/filters: Add ascii graphics to clarify what the currently implemented tinterlace modes do

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/matroskadec: fix handling of recursive SeekHead elements

When matroska_execute_seekhead() is called, it goes through the list of
seekhead entries and attempts to read elements not read yet. When doing
this, the parser can find further SeekHead elements, and will extend the
matroska->seekhead list. This can lead to a (practically) infinite loop
with certain broken files. (Maybe it can happen even with valid files.
The demuxer doesn't seem to check correctly whether an element has
already been read.)

Fix this by ignoring elements that were added to the seekhead field
during executing seekhead entries.

This does not fix the possible situation when multiple SeekHead elements
after the file header (i.e. occur after the "before_pos" file position)
point to the same elements. These elements will probably be parsed
multiple times, likely leading to bugs.

Fixes ticket #4162.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/matroskadec: request a sample with recursive seek heads

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