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

Justin Ruggles justinruggles
Sun Feb 18 07:14:42 CET 2007

Justin Ruggles wrote:
> 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.

It's been over a week now, so I just wanted to let everyone know I am
still working on this.  I've moved all common code between the encoder,
decoder, and parser to ac3.c.  The code has been cleaned up and
commented.  Downmixing works great and is in a separate file, ac3mix.h.
   Speed is good for stereo content, same speed as liba52 on my system.
 I still have 3 issues I need to sort out though.

1) still don't have 256-point IMDCT working.  I've made it add silence
   instead of loud pops though.

2) 6-channel output doesn't seem to be working properly.

3) 5.1-channel decoding speed is about 40% slower than liba52 on my

Once I get these fixed, I'll post a new patch.


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