FDK AAC encoder/decoder : Access Huffman encoded and decoded data

Question

For the FDK AAC, I want to access the spectral data before and after Huffman encoding/decoding in the encoder and in the decoder. For accessing spectral data before Huffman encoding, I am using pSpectralCoefficient pointer and dumping 1024 samples (on the decoder side) and using qcOutChannel[ch]->quantSpec and dumping 1024 samples (on the encoder side). Is this correct?

Secondly, how do access the Huffman encoded signal in the encoder and decoder. If someone can tell me the location in the code and the name of the pointer to use and the length of this data, I will be extremely thankful.

Thirdly, I wanted to know that what is the frame size in frequency domain(before huffman encoding)? I am dumping 1024 samples of *pSpectralCoefficient. Is that correct? Is it possible that some frames are 1024 in length and others are a set of 8 frames with 128 frequency bins. If it is possible, then is there any flag that can give me this information ?

Thank you for your time. Request you please help me out with this as soon as possible.

Regards, Akshay

Answer 1

To pull out that specific data from the bitstream you will need to step through the decoder and find the desired peaces of stream. In order to do that you have to have the AAC bitstream specification. Current AAC specification is:

ISO/IEC 14496-3:2009 "Information technology -- Coding of audio-visual objects -- Part 3: Audio"