Improves CABAC performance about ~1.2%.

Trick originates from x264 and has also been used in ffvp8.  It's useful because
coded block flags are usually zero, so it helps to have the early termination
inlined into the main function.

Originally committed as revision 26375 to svn://svn.ffmpeg.org/ffmpeg/trunk

More consistent with the rest of FFmpeg and sounds more natural to
English speaking people.

Originally committed as revision 26374 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26373 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26372 to svn://svn.ffmpeg.org/ffmpeg/trunk

Fixes issue 1017.

Originally committed as revision 26371 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26370 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26369 to svn://svn.ffmpeg.org/ffmpeg/trunk

The hunk is not fully understood but it just makes a check tighter so its
safer for us to apply until it is fully understood.

Might fix issue 2550 (and Chrome issue 68115 and unknown CERT issues).
Our bugtracker issue though should stay open until this has been fully
investiagted

Patch by Frank Barchard, fbarchard at google

Originally committed as revision 26368 to svn://svn.ffmpeg.org/ffmpeg/trunk

fixes issue 2543

Originally committed as revision 26367 to svn://svn.ffmpeg.org/ffmpeg/trunk

This should improve duration accuracy slightly and avoids a warning about its
inaccuracy when accurate values are available. Idea by Frank Barchard

Originally committed as revision 26366 to svn://svn.ffmpeg.org/ffmpeg/trunk

Fixes issue 2548 (and Chrome issue 68115 and unknown CERT issues).

Patch by Frank Barchard, fbarchard at google

Originally committed as revision 26365 to svn://svn.ffmpeg.org/ffmpeg/trunk

instead of real width, this fixes decoding of some Bink files with odd width.

Originally committed as revision 26364 to svn://svn.ffmpeg.org/ffmpeg/trunk

color value instead of always taking 0 (resulting in green frames).
Fixes issue issue2531.

Originally committed as revision 26363 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26362 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26361 to svn://svn.ffmpeg.org/ffmpeg/trunk

Patch by Daniel Kang, daniel.d.kang at gmail

Originally committed as revision 26360 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26359 to svn://svn.ffmpeg.org/ffmpeg/trunk

43% faster in function encode_exponents().

Originally committed as revision 26358 to svn://svn.ffmpeg.org/ffmpeg/trunk

simplify and speed up encode_exponents().
8% faster in function.

Originally committed as revision 26357 to svn://svn.ffmpeg.org/ffmpeg/trunk

exponent strategies for a single channel to compute_exp_strategy_ch().
This allows for removal of the temporary pointer arrays.

Originally committed as revision 26356 to svn://svn.ffmpeg.org/ffmpeg/trunk

code.

Originally committed as revision 26355 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26354 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26353 to svn://svn.ffmpeg.org/ffmpeg/trunk

channel first, then by block.

Originally committed as revision 26352 to svn://svn.ffmpeg.org/ffmpeg/trunk

This will allow for faster and simpler processing of all blocks at once.

Originally committed as revision 26351 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26350 to svn://svn.ffmpeg.org/ffmpeg/trunk

No speed improvement, but necessary for some future stuff.
Also opens up the possibility of asm chroma dc idct/dequant.

Originally committed as revision 26349 to svn://svn.ffmpeg.org/ffmpeg/trunk

Doesn't help speed as there isn't an asm implementation yet, but consistency
is a good thing.

Originally committed as revision 26348 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26347 to svn://svn.ffmpeg.org/ffmpeg/trunk

fixes issue 2539

Originally committed as revision 26346 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26345 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26344 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26343 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26342 to svn://svn.ffmpeg.org/ffmpeg/trunk

Regression in r26336-7.

Originally committed as revision 26341 to svn://svn.ffmpeg.org/ffmpeg/trunk

This should avoid non monotone timestamps for video streams with vfr.

Originally committed as revision 26340 to svn://svn.ffmpeg.org/ffmpeg/trunk

Since we no longer have non-transposed scantables, the problem it warns about
no longer exists.

Originally committed as revision 26339 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26338 to svn://svn.ffmpeg.org/ffmpeg/trunk

Useful so that we don't have to run the hierarchical DC iDCT if there aren't
any coefficients.  Opens up some future opportunities for optimization as well.

Originally committed as revision 26337 to svn://svn.ffmpeg.org/ffmpeg/trunk

About 2.5x the speed.

NOTE: the way that the asm code handles large qmuls is a bit suboptimal.
If x264-style dequant was used (separate shift and qmul values), it might
be possible to get some extra speed.

Originally committed as revision 26336 to svn://svn.ffmpeg.org/ffmpeg/trunk