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Please Help, Explain MPEG-2 AAC Huffman Codebook
Clone2
post Feb 24 2014, 13:04
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This link is a picture of MPEG-2 AAC Codebook :
https://lh5.googleusercontent.com/-Wn3Y5gn3...24_18-43-57.png

Can someone explain what is signed and unsigned values?? How can it be signed and and unsigned??
If can, please also help explain about codebook index, n-tuple size, and maximum absolute values too...
please help me.... Thanks in advance... smile.gif

I'm a newbie and interested in audio coding.
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Garf
post Feb 24 2014, 13:35
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IIRC, the unsigned values simply transmit the values separately from the sign bits.

Maximum absolute value is just the biggest value in the codebook.

n-tuple: how many spectral values are represented by 1 codebook value
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Clone2
post Feb 24 2014, 16:55
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QUOTE (Garf @ Feb 24 2014, 19:35) *
IIRC, the unsigned values simply transmit the values separately from the sign bits.

Maximum absolute value is just the biggest value in the codebook.

n-tuple: how many spectral values are represented by 1 codebook value


but, what make the bits become signed or unsigned value??
thank you... smile.gif
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Garf
post Feb 25 2014, 08:14
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The table you posted tells you which of the two it is depending on the codebook index.

i.e. the signed codebooks will have tuples like [0, -1, 0, +1].
the unsigned one will have tuples like [0, 1, 0, 2] followed (or preceded, check the AAC standard) by [-, +] giving you [0, -1, 0, +2]
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Clone2
post Feb 25 2014, 11:34
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Ooh I see now...

Thank you very much, mr. Garf... ^^
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