view wiki/AIMCDataFormat.wiki @ 705:be2b68ced23d

Make the C++ SAI match the Matlab implementation.

 - Fix syntax error which caused a linear window to be used instead of the correct sine window.
 - Correct off-by-one indexing errors to compensate for 1-based indexing in Matlab.
 - Enable test to verify that the C++ output matches Matlab with high precision.

#summary AIM-C simple data file format.

The module [http://code.google.com/p/aimc/source/browse/trunk/src/Modules/Output/FileOutputAIMC.cc FileOutputAIMC] provides data in a simple format which can be read by other programs. 

The data is stored as 32-bit floats with the native byte-ordering of the machine the file was written on. Before the data, there is a simple header.

== Header format == 
The first 20 bytes of the file contain the following fields:

  * 32-bit unsigned integer: frame count - total number of frames in the file (these can be SAIs, filterbank output frames or other things (eg. features), but all frames in the file are of the same type)
  * 32-bit float: frame period (the interval between adjacent frames in milliseconds) (TODO(tom): this is currently not set properly).
  * 32-bit unsigned integer: channel count (number of frequency channels in the output)
  * 32-bit unsigned integer frame length (length of each frame in samples)
  * 32-bit float: sample rate (audio sample rate in Hz)


== Reading the files using MATLAB ==
Use [http://code.google.com/p/aimc/source/browse/trunk/matlab/AIMCread.m the MATLAB AIMCread function] to read the files.