This commit also makes sure the extradata and subtitle_header are NUL
terminated, without taking into account the trailing '\0' in account in
the size.

At the same time, it should fix 'warning: dereferencing type-punned
pointer will break strict-aliasing rules' warning for compilers who
don't consider uint8_t** and char** compatibles.

Signed-off-by: Martin Storsjö <martin@martin.st>

Fixes a part of Ticket1208

Found-by: John Villamil and Piotr Bandurski
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Signed-off-by: Aurelien Jacobs <aurel@gnuage.org>

Call this new function before decode() to replace the custom and
inconsistant initialization in various decoders.
This function is equivalent to avcodec_get_frame_defaults() for AVFrame.
Signed-off-by: Aurelien Jacobs <aurel@gnuage.org>

Signed-off-by: Mans Rullgard <mans@mansr.com>

None of these symbols should be accessed directly, so declare them as
hidden.
Signed-off-by: Mans Rullgard <mans@mansr.com>
(cherry picked from commit d36beb3f)

None of these symbols should be accessed directly, so declare them as
hidden.
Signed-off-by: Mans Rullgard <mans@mansr.com>

Originally committed as revision 25747 to svn://svn.ffmpeg.org/ffmpeg/trunk