Monday, August 21, 2006

version 0.05

Version 0.05 has been released. The speed increase since version 0.04 really warranted another release. There have also been a few bug fixes.

Saturday, August 19, 2006

doubles or floats

I decided to switch the default configuration for the floating-point type. Now using floats is default, and "--enable-double" enables use of doubles.

Friday, August 18, 2006

floats or doubles

There is now a configure switch to enable use of floats internally instead of doubles. This is less accurate, but faster. To use floats, just add "--enable-float" when running configure. Otherwise, Aften will use doubles.

Saturday, August 12, 2006

Sample Format choices

I have modified by libaften and the Aften wav reader to be able to use various sample formats. Aften still uses doubles internally, but the input can be any one of the most common pcm sample format types.

It wasn't absolutely necessary for me to add this functionality to the wav reader, but I did it so that wav.c can be easily reused for other purposes.

Friday, August 11, 2006

more functional separation

I moved all of the exponent processing functions from a52enc.c to exponent.c. This was in preparation for a new exponent strategy decision algorithm, which I am working on now.

Monday, August 07, 2006

bit allocation speedup

Thanks to the help of Prakash Punnoor (, the bit allocation in Aften is much faster. On my system, there was a 22% speedup for CBR and 36% speedup for VBR!!

Sunday, August 06, 2006

Daily builds

I have setup daily builds from SVN. Every day at 4:50am EST my computer will get the latest SVN version of Aften and build a source package and a Windows binary package. They will be located at:

Saturday, August 05, 2006

Aften 0.04 released

I have setup a Sourceforge project for Aften, where I have released version 0.04.
Benefits of putting Aften on Sourceforge:
  • SVN access to the latest development changes.
  • Organized file releases
  • Mailing lists (currently, there is only an svnlog mailing list)
  • More publicity
  • Opportunity for other developers to join the project
  • Web hosting (the new Aften webpage is

Friday, August 04, 2006

Default Bitrate

I made a few minor changes regarding bitrate. First, CBR mode is now the default instead of VBR. The default CBR bitrate is chosen based on the number of full-bandwidth channels.
1: 96 kbps
2: 192 kbps
3: 256 kbps
4: 384 kbps
5: 448 kbps

I modified the Aften commandline to accept bitrate in kbps instead of bps (i.e. '-b 192' instead of '-b 192000').

Now you can use the '-b' option along with the '-q' option. This will use VBR mode and use the given bitrate as a maximum bitrate.

Wednesday, August 02, 2006


I finally created a libaften! If there are no problems with the new configure/build system, I will release version 0.04 soon.

I decided not to make the filter library separate. It just made things too complicated. So now there is the base directory, aften, libaften, and util. Currently only a static library is built, but I will eventually add support for compiling a dynamic library/dll.

Tuesday, August 01, 2006

Bandwidth stuff

I have done some reworking of the bandwidth calculation. Now there are 2 adaptive modes. The default is now a fixed adaptive bandwidth, which is chosen at the start of encoding based on either the quality or bitrate setting. The other is the same variable bandwidth as before, but with a different formula. I did this mainly to make the bandwidth filter work better. There is a distinct quality difference in the high frequencies when using the fixed adaptive bandwidth coupled with the bandwidth pre-encoding filter.

commandline option changes:
'-bwfilter 1' = enable bandwidth filter
'-w -1' = fixed adaptive bandwidth (default)
'-w -2' = variable adaptive bandwidth (cannot use bandwidth filter w/ this mode)