IPB

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
SNR bit allocation method in SBC, what is the relation between SNR and this bit allocation method
Database4
post Oct 30 2010, 17:47
Post #1





Group: Members
Posts: 9
Joined: 17-June 09
Member No.: 70756



Hi,
I am new to the audio, and i am trying to understand SBC Encoder. How SNR bit allocation method is related to the signal to noise ration?
In calculation of the scale factors, can we take scale factor of subband as number of bits of max subband sample?

Please help me to understand above.

Thanks in advance.

Regards,
Sapthagiri.
Go to the top of the page
+Quote Post
SebastianG
post Dec 9 2010, 13:49
Post #2





Group: Developer
Posts: 1317
Joined: 20-March 04
From: Göttingen (DE)
Member No.: 12875



QUOTE (Database4 @ Oct 30 2010, 17:47) *
I am new to the audio, and i am trying to understand SBC Encoder. How SNR bit allocation method is related to the signal to noise ratio?

In calculation of the scale factors, can we take scale factor of subband as number of bits of max subband sample?

Yes. That's the idea. This will lead to a flat quantization noise spectrum. In terms of psychoacoustics this is not desirable though. The other bit allocation approach is still very simple but accounts for some psychoacoustic effects. So, if I recall correctly, it's be like this:
CODE
// for SNR bit allocation strategy
bitsneeded = scalefactor

// for the other strategy
bitsneeded = (scalefactor - table[subband]) / 2;

where table contains some offsets depending on the frequency.

Then, allocation is iterativly adjusted so that nearly all bits from the bit pool are spent.
Go to the top of the page
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 31st July 2014 - 17:03