[Ffmpeg-devel] FLAC encoder

[Justin Ruggles]

Benjamin Larsson wrote:
> Justin Ruggles wrote:
> 
> 
>>Hello,
>>
>>I wrote:
>> 
>>
>>
>>>Well, the FLAC encoder is getting better by the day.  I'll post some
>>>results some time soon of my most recent version, which has marked
>>>improvement in compression.
>>>   
>>>
>>
>>Here are some current results.  The latest version is here:
>>
>>http://home.earthlink.net/~jruggle/flake/flake-02.tar.bz2
>>
>>I still haven't integrated with FFmpeg...that's coming soon though.  The
>>biggest improvement I have made is the application of a window function
>>before calculating the LPC coefficients.  After testing several
>>different window types, I found that for most audio clips, either the
>>Hamming window or the Bartlett window was the best choice.  So I changed
>>the encoder to calculate LPC coefficients using each of these windows.
>> 
>>
> 
> Regaring the choise of window, read this thread:
> http://www.hydrogenaudio.org/forums/index.php?showtopic=44229
> Hope it helps.

Wow, thanks Benjamin! This is great!


> 
>>Optimal LPC order estimation is done for each set, and the smaller order
>>of the 2 is used along with the corresponding coeffs.  It's amazing how
>>such a simple thing can increase compression so much!  I got the idea
> 
>>from a general description of MPEG-4 ALS.  It could be patented for all
> 
>>I know...
>>
>>If anyone wants to do tests with the clip I used for the test below:
>>http://home.earthlink.net/~jruggle/flake/answering_bell.flac
>>
>>-Justin
>> 
>>
> 
> MvH
> Benjamin Larsson
>