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Topic: Questions about RC4 Spec (Read 4170 times) previous topic - next topic
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Questions about RC4 Spec

I posted this question in wrong place and realized it would be better off in here, for those of you familiar with source-code.

Window Switching:

Correct me if I am wrong, but I thought that monty was also aiming to make the window switching algorithm faster for the RC4 release? maybe not. I have the source-code here and I am still looking through it <window.c>. Is it possible to use more than one window function? what's the deal with preclamping the window as well? is that to control bit allocation or for something else like pre-echo? Would adding another sine window function have an impact on control of long and short windows? The current sine window seems fine I was just curious.

Next up checking out the <phytune.c> physcoacoustic tuning source.
budding I.T professional

Questions about RC4 Spec

Reply #1 –
Quote
Originally posted by HotshotGG
I posted this question in wrong place and realized it would be better off in here, for those of you familiar with source-code. 

Window Switching:

Correct me if I am wrong, but I thought that monty was also aiming to make the window switching algorithm faster for the RC4 release? maybe not. I have the source-code here and I am still looking through it <window.c>. Is it possible to use more than one window function? 


Yes, but the decoder needs to know about it, so for Vorbis I you can only use window 0.

Quote
what's the deal with preclamping the window as well?


What do you mean?

--
GCP

Questions about RC4 Spec

Reply #2 –
what is the exact purpose of pre-echo clamp trigger threshold I guess is what my questions is? if you pre-clamp the window does that mean you can get results just as good as using short blocks and have the ability to use a fixed block size as well?

I also have another question to throw in, has monty started working on some form of a Hybrid Discrete Wavelet Transform or coming up with any ideas in general at this stage yet? like exactly how to design the filterbank? or is this out of the question for the time being? would pre-clamping seem more likely to be use in Vorbis I release?
budding I.T professional

Questions about RC4 Spec

Reply #3 –
Quote
Originally posted by HotshotGG
what is the exact purpose of pre-echo clamp trigger threshold I guess is what my questions is? if you pre-clamp the window does that mean you can get results just as good as using short blocks and have the ability to use a fixed block size as well?
Straight from Monty:
"'pre echo clamp trigger'  there is no such thing in Vorbis I.  There was a struct field named that at one point when I was still playing with it.  None of that was ever deployed into the Vorbis I."
Quote
I also have another question to throw in, has monty started working on some form of a Hybrid Discrete Wavelet Transform or coming up with any ideas in general at this stage yet? like exactly how to design the filterbank? or is this out of the question for the time being? would pre-clamping seem more likely to be use in Vorbis I release?
"'started working on wavelets'.  I played with them alot about five years ago.  There is nothing yet that I have firmly in mind to deploy in Vorbis II."
Juha Laaksonheimo

Questions about RC4 Spec

Reply #4 –
Thanks for the replies I appreciate it. I had been directly referring to that structure in the <phytune.c> when I was speaking of the pre-echo clamp trigger threshold. I couldn't figure out what that was. I had intended to ask the question if pre-clamping the window had given good results just as good as reverting to short-blocks and if that is the plan for Vorbis I final release or making the window switching algorithm faster.
budding I.T professional