A large portion of this code was orignally authored by Robert Swain. The rest
was written by me. Full history is available at:
svn://svn.ffmpeg.org/soc/aac-sbr
http://github.com/aconverse/ffmpeg-heaac/tree/sbr_pub

Originally committed as revision 22316 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 22299 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 22298 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 22287 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 22235 to svn://svn.ffmpeg.org/ffmpeg/trunk

The libfaad wrapper does this.

Originally committed as revision 22206 to svn://svn.ffmpeg.org/ffmpeg/trunk

This results in a 50% speedup on main profile with no increase in binary size.

Originally committed as revision 22196 to svn://svn.ffmpeg.org/ffmpeg/trunk

Due to a shortcoming in the AAC specification, if an all zero buffer is
fed to section data decoding it will never terminate. That means without
a buffer exhaustion check decode_band_types() will consume all input
buffer padding. Worse if a get_bits() implementation that returns zeros
when padding is exhausted is used, the function will never terminate.

The fixes that by added a buffer exhaustion check in the sectioning
decoding loop.

Originally committed as revision 22044 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 21886 to svn://svn.ffmpeg.org/ffmpeg/trunk

It is also only called when the output configuration is not locked.

Originally committed as revision 21834 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 21833 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 21739 to svn://svn.ffmpeg.org/ffmpeg/trunk

Using the low-level macros directly avoids redundant open/update/close
cycles.

2-3% faster on ARM, PPC, and Core i7.

Originally committed as revision 21224 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 21219 to svn://svn.ffmpeg.org/ffmpeg/trunk

Up to 6% faster overall on i7, no change on A8.

Originally committed as revision 21191 to svn://svn.ffmpeg.org/ffmpeg/trunk

GCC should be able to do this, but doesn't.  Slightly faster code.

Originally committed as revision 21190 to svn://svn.ffmpeg.org/ffmpeg/trunk

Simplify cur_band_type, group_len, and coef/offset calculations.  This
makes the code easier to read and slightly faster.

Originally committed as revision 21189 to svn://svn.ffmpeg.org/ffmpeg/trunk

The codebooks each consist of small number of values repeated in
groups of 2 or 4.  Storing the codebooks as a packed list of 2- or
4-bit indexes into a table reduces their size substantially (from 7.5k
to 1.5k), resulting in less cache pressure.

For the band types with sign bits in the bitstream, storing the number
and position of non-zero codebook values using a few bits avoids
multiple get_bits() calls and floating-point comparisons which gcc
handles miserably.

Some float/int type punning also avoids gcc brain damage.

Overall speedup 20-35% on Cortex-A8, 20% on Core i7.

Originally committed as revision 21188 to svn://svn.ffmpeg.org/ffmpeg/trunk

The maximum length of escape_sequence is 21 bits, so adjust limit in
code to match this.

Up to 10% faster on Cortex-A8.

Originally committed as revision 21153 to svn://svn.ffmpeg.org/ffmpeg/trunk

The maximum length of escape_sequence is 21 bits, so adjust limit in
code to match this.  Also fix the comment.

Originally committed as revision 21151 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 21108 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 21099 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 20879 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 20874 to svn://svn.ffmpeg.org/ffmpeg/trunk

other means)

Originally committed as revision 20773 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 20701 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 20700 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 20570 to svn://svn.ffmpeg.org/ffmpeg/trunk

length of the section.

Originally committed as revision 20513 to svn://svn.ffmpeg.org/ffmpeg/trunk

non extradata formats. Instead lock it only after the successful decoding of a
frame. This fixes issue 999.

Originally committed as revision 20448 to svn://svn.ffmpeg.org/ffmpeg/trunk

signalled as having a channel configuration of 1 in output_configure().
Previously this didn't matter but it does now.

Originally committed as revision 20193 to svn://svn.ffmpeg.org/ffmpeg/trunk

the C version of that rather than float_to_int16.
Fixes output on ARM/VFP

Originally committed as revision 20192 to svn://svn.ffmpeg.org/ffmpeg/trunk

to allow reuse

Originally committed as revision 20069 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 20068 to svn://svn.ffmpeg.org/ffmpeg/trunk

specification

Originally committed as revision 20067 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 19999 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 19970 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 19958 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 19956 to svn://svn.ffmpeg.org/ffmpeg/trunk

.data section.

Originally committed as revision 19787 to svn://svn.ffmpeg.org/ffmpeg/trunk