[M4IF Technotes] IDCT scaling (down & up) by non-power two

[moses kampsax.dtu.dk]

Hi all 
I'm new for the IDCT JPEg still image. I'm using the IJG library to 
implement arbitrary scaling an JPEG still image. IJG has only the power of 
2 scaling decoder methods. 
1. which is algorithm the fast one for this problem? 
2. Do you have any example of it or where to find (link)? 
3. Is it used by the MPEG-2 or 4? 
I will appreciate if you could help with these problems. 
I'm looking forward to have your help. 
Best regards 
Moses