see https://wiki.debian.org/Autoreconf

upstream/6.1

From Libav11 only setting the codec time_base triggers a warning.

This the correct pattern since Libav 0.6.

It was not really packaged, and it was the standard automake one, there's no reason to keep it around.

This allows loading tiff files with libav without waiting for libav 11 but
it will create colour files by default, even though the image would be
grayscale only.

libav 11 supports grayscale tiff files as grayscale rather than palettized,
but until then, this workaround should work.

Apply the zoomfactor on the requested sizes, and always call stretch().

If the stretch() would make the image the same size, simply avoid
processing altogether.

Now these two functions use the global maskColor and it makes the code
simpler.

This makes the code simpler because only initImage() needs to access the
global parameter then.

Since resizing and stretching are so similar, factor out their base code
without the allocations.

Most of the functions don't need to modify the pointer, only loading and
canvas-modifying functions need those, everything else only needs to access
the frame.

Instead use av_frame_free() directly.

This changes only the file output functions to not use the double-pointers
but just the read-only single pointer, more will follow.

Now IMAGE is just a pointer to AVFrame.

The mask checking was only used in that unit so keep it over there and
inline it. The compiler can easily optimize for this and the result is that
there is no overhead in the inlining.