Originally posted by sam 1. how to calculate pow(x, 4.0/3.0) for x = 0, 1, ..., 8191 What about a look up table? Be quicker and you can tune the results how you wish. I can provide the answeres for you to any number of dp.
Originally posted by Gabriel Perhaps it should also be possible to not compute this at all. After all, for decoding you have to compute this power after Huffman decoding, so perhaps it could be directly included into this decoding.
Originally posted by smack I had also encountered the problem of pow(x,4/3) computation when I implemented a Layer 3 decoder for a DSP. After testing some approximation calculations which took too much computing power and were not accurate enough I simply used a full (8K) lookup table.
Btw. what DSP are you using? I managed to implement a MPEG-1 layer 3 decoder (including the 8K table) on a Motorola DSP with a total of 32 KWords of memory.(source codes available under GNU GPL ;-)
Originally posted by Ivan Dimkovic Check out the:AES Paper #5363"Optimized DSP Implementation of Non-Linear Quantization"(Raghunath K. Rao and Girish P. Subramaniam)Presented at the 110th Convention2001 May 12?5 Amsterdam, The Netherlands
Originally posted by smack The Motorola DSP has 24bit words, I found the accuracy of the single precision table good enough. (IIRC the error is less than 0.5%)I had posted the links to my programs in another thread:http://www.hydrogenaudio.org/forums/showth...hp?threadid=840
Originally posted by encai That is what I need. How can I get a E-version(such as PDF file etc...) of it.
Originally posted by Gabriel A common solution is to use only a small table of let's say 1026 valuesif i <1026 then direct lookupif i >1025 then i = i/8, then lookup, then i = i*16This involves only lookups and shiftings so it's quite fast, and reduces a lot the table size