Indeo Audio: Difference between revisions

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* Samples: http://samples.mplayerhq.hu/A-codecs/Indeo_audio/
* Samples: http://samples.mplayerhq.hu/A-codecs/Indeo_audio/


Probably related to the Intel Music Coder.
This is the next version of [[Intel Music Coder]] with slightly different coding parameters
(all algorithms are the same) and joint stereo mode.
 
=== Header format ===
 
  bit  0  - should be zero
  bit  1  - should be zero
  bit  2  - stereo flag
  bits 3-8 - block size code
  bit  9  - codebook set selector (0 - no escapes, 1 - with escapes)
  bit 10  - codebook selector
  bit 11  - use raw coding
 
  bit 12  - SNR offset (-30 or -10)
 
 
Block size code:
 
  0, 34-50 - (block_size + 14) 16-bit words
  33      - 32 words
  1-32    - (block_size + 15) words
  51-63    - invalid value
 
=== Levels ===
 
There are 32 levels, coded with either one of codebooks or in raw form.
 
Decoding Huffman-coded levels is the same as in [[Intel Music Coder]] but with different tables.
 
Raw form:
 
  1st coefficient - 5 bits
  2nd coefficient - 7 bits
  others          - 4 bits per coefficient
 
Level reconstruction is also the same as in [[Intel Music Coder]] except for raw form.


[[Category:Audio Codecs]]
[[Category:Audio Codecs]]
[[Category:Undiscovered Audio Codecs]]
[[Category:Incomplete Audio Codecs]]

Revision as of 08:03, 9 June 2012

This is the next version of Intel Music Coder with slightly different coding parameters (all algorithms are the same) and joint stereo mode.

Header format

  bit  0   - should be zero
  bit  1   - should be zero
  bit  2   - stereo flag
  bits 3-8 - block size code
  bit  9   - codebook set selector (0 - no escapes, 1 - with escapes)
  bit 10   - codebook selector
  bit 11   - use raw coding
  
  bit 12   - SNR offset (-30 or -10)


Block size code:

  0, 34-50 - (block_size + 14) 16-bit words
  33       - 32 words
  1-32     - (block_size + 15) words
  51-63    - invalid value

Levels

There are 32 levels, coded with either one of codebooks or in raw form.

Decoding Huffman-coded levels is the same as in Intel Music Coder but with different tables.

Raw form:

  1st coefficient - 5 bits
  2nd coefficient - 7 bits
  others          - 4 bits per coefficient

Level reconstruction is also the same as in Intel Music Coder except for raw form.