height - me_y is the line from which we read, so it must be strictly
smaller than the frame height. Fixes possible invalid reads in corrupted
files.

Also, use a proper context for logging the error.

CC: libav-stable@libav.org
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind

If we encounter an END element before anything is decoded, we would
return success even though the output frame has not been allocated,
which is invalid.

CC: libav-stable@libav.org
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind

Fixes possible invalid writes with corrupted files.

CC: libav-stable@libav.org
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind

This gem has been disabled since 2001.

The lowest supported VAAPI version is 0.34 (checked at configure
time), so this test is no longer needed.

If no string argument is supplied when av_hwdevice_ctx_create() is
called to create a VAAPI device, we currently only try the default
X11 display (that is, $DISPLAY) to find a device, and will therefore
fail in the absence of an X server to connect to.  Change the logic
to also look for a device via the first DRM render node (that is,
"/dev/dri/renderD128"), which is probably the right thing to use in
most simple configurations which only have one DRM device.

Unbreak `avconv -filter_complex testsrc`.

Regression introduced in a3a0230a

Signed-off-by: Anton Khirnov <anton@khirnov.net>

This will be needed for frame threading.
Signed-off-by: Anton Khirnov <anton@khirnov.net>

We need more information from last/cur_frame than from reference
buffers, so we can use a simplified structure for reference buffers,
and then store mvs and segmentation map information in last/cur.

This prepares the decoder for frame threading support.
Signed-off-by: Anton Khirnov <anton@khirnov.net>

Not from the underlying frame. Fixes races with frame threading in
field-coded files, where decoding would wait for the wrong field (e.g.
random failures in mixed-nal-coding).

Bug-Id: 954