[Vorbis] ***SPAM*** encoder flow chart

[fangchao]

Hi
Any help is appreciate!
These days I studied ogg vorbis encoder with sample rate 44.1kbsp,and I thought the whole chart was as follows:
1.  read the PCM data and store them in a buffer
2.  do MDCT on those PCM data 
3.  do FFT  on those PCM data
4.  use both the FFT and MDCT coefficient to the psychoacustic modle and derive an maximum allowable noise curve, 
    and during this curse ,do the window anlysis and decide which window to use for the next coming PCM data 
5.  use the psychoacustic result on the MDCT coefficient and remove those below the maximum allowable noise curve 
6.  do floor anlysis , encode the floor  and pack them in the bitstream
7.  do residue = MDCT/floor ,derive residue curve and choose one type of residue encoder method and use huffman tree 
    to pack them in the bitstream(use stereo coupling when multiple channels).
8.  if it is not the end of the coming PCM data,do the loop again.
For the first time,we use a short window ,after that, we decide the type of window according to the psychoacustic model.
Is it all right ? 
Looking forward for your letter!
Best regards 

	


 				

　　　　　　　  Lisa
　　　　　　　　fangchao_dlut at sina.com
　　　　　　　　　　2005-09-27