[Ffmpeg-devel] [PATCH] updated LGPL AC-3 decoder

[Justin Ruggles]

Hello,

Here is what I have so far in my attempts to merge the AC-3 decoder
written by Kartikey Mahendra BHATT for the Google Summer of Code.  There
are some things which still need work, and I have some enhancements
planned for after it's included.  Right now, this gives generally
working results, but has some issues.

The 256-point MDCT is not working correctly.  I'm still trying to get
that fixed.  Also, the downmixing seems to not always work like it
should.  The code could use some clean-up as well.

The patch I've attached is against current SVN.  The ac3.c and
ac3_decoder.c files go into libavcodec.  When it's committed, ac3.c will
be created by doing an svn copy of ac3enc.c and then patching it to what
I've included here.  I think I got the build system stuff right, but I'm
not completely sure.

Here is a summary of the changes to the decoder:
 - used the new av_random for dithering
 - used the common bit allocation code from ac3enc.c (via ac3.c)
 - replaced the exponent decoding, which was from liba52 (GPL), with an
   implementation I wrote for my own AC-3 parser, which is LGPL.
 - reused some of the macros from ac3.h and got rid of ac3_decoder.h

I really want to fix the short block MDCT before merging this, but I
thought I would go ahead and post what I have so it could be reviewed.

Thanks,
Justin

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