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Topic: Queries in Filterbank (Read 2614 times) previous topic - next topic
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Queries in Filterbank

"After the 32-band PQMF filter, blocks of 36 sub-band samples are overlapped by 50%, multiplied by a sine window and then processed by the MDCT transform...."

I read this from a book, it is about Layer III Hybrid Filter Bank. My query is, how can we ensure there are 36 sub-band samples in each of the 32-band? Aren't the number of samples proportional to the length of the data?

Queries in Filterbank

Reply #1 –
At first step audio data is divided in frames of exactly 1152 samples each. This gives us 1152 / 32 = 36 samples is each subband after PQF.

-Eugene
The  greatest  programming  project of all took six days;  on the seventh  day  the  programmer  rested.  We've been trying to debug the !@#$%&* thing ever since. Moral: design before you implement.
 

Queries in Filterbank

Reply #2 –
No.. The audio data is divided into frames of 576 samples.. So 576 / 32 gives you 18 samples per subband.. You have to combine the 18 samples of the previous frame to get 32 samples per subband for the MDCT calculation.