Up until now, VLCs that were part of an array of VLCs were often not
initialized in a loop, but separately. The probable reason for this
was that these VLCs differed slightly in the parameters to be used for
them (i.e. the number of codes or the number of bits to be used
differs), so that one would have to provide these parameters e.g. via
arrays.
Yet these problems have actually largely been solved by now: The length
information is contained in a run-length encoded form that is the same
for all VLCs and both the number of codes as well as the number of bits
to use for each VLC can be easily derived from them.
There is just one problem to be solved: When the underlying tables have
a different number of elements, putting them into an array of arrays
would be wasteful; using an array of pointers to the arrays would
also be wasteful. Therefore this commit combines the tables into bigger
tables. (Given that all the length tables have the same layout this
applies only to the symbols tables.)
Finally, the array containing the offset of the VLC's buffer in the big
buffer has also been removed.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
After permuting both length, code as well as symbol tables so that
the codes are ordered from left to right in the tree, it became apparent
that the length of the codes decreases from left to right. Therefore one
can run-length encode the lengths to save space. This commit implements
this.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
By switching to ff_init_vlc_from_lengths() one can make a table of
codes of type uint8_t superfluous, saving space.
Other VLCs (those without dedicated symbols table and with codes of
type uint8_t) have been made to use ff_init_vlc_from_lengths(), too,
because it reduces codesize (ff_init_vlc_from_lengths() has two
parameters less than ff_init_vlc_sparse()) and because it allows to
use the offset parameter in future commits.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
mpc8_q4_syms is an array of int8_t that is initialized using
values not in the range of an int8_t and that is only accessed via
a pointer to uint8_t in ff_init_vlc_sparse. The latter applies to all
the other *_bits and *_syms tables in mpc8huff.h, so make them all
unsigned.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Consistently apply this rule: the guard name is obtained from the
filename by stripping the leading "lib", converting '/' and '.' to
'_' and uppercasing the resulting name. Guard names in the root
directory have to be prefixed by "FFMPEG_".
Originally committed as revision 15120 to svn://svn.ffmpeg.org/ffmpeg/trunk
Andreas Rheinhardt