header.doc

speech signal process tools

                       NIST SPHERE Header Structure


The NIST SPHERE header is an object-oriented, 1024-byte blocked, ASCII 
structure which is prepended to the waveform data.  The header is composed 
of a fixed-format portion followed by an object-oriented variable portion.  
The fixed portion is as follows:

NIST_1A<new-line>
   1024<new-line>

The first line specifies the header type and the second line specifies the
header length.  Each of these lines are 8 bytes long (including new-line) and
are structured to identify the header as well as allow those who do not wish
to read the subsequent header information to programmatically skip over it. 


The remaining object-oriented variable portion is composed of
object-type-value "triple" lines which have the following format:


<LINE> ::= <TRIPLE><new-line> |
           <COMMENT><new-line> | 
           <TRIPLE><COMMENT><new-line> | 

  <TRIPLE> ::= <OBJECT><space><TYPE><space><VALUE><OPT-SPACES>

    <OBJECT> ::= <PRIMARY-SUBOBJECT> | 
                 <PRIMARY-SUBOBJECT><SECONDARY-SUBOBJECT>

    <PRIMARY-SUBOBJECT> ::= <ALPHA> | <ALPHA><ALPHA-NUM-STRING>
    <SECONDARY-SUBOBJECT> ::= _<ALPHA-NUM-STRING> | 
                              _<ALPHA-NUM-STRING><SECONDARY-SUBOBJECT>

    <TYPE> ::= -<INTEGER-FLAG> | -<REAL-FLAG> | -<STRING-FLAG>

      <INTEGER-FLAG> ::= i
      <REAL-FLAG> ::= r
      <STRING-FLAG> ::= s<DIGIT-STRING>
      
    <VALUE> ::= <INTEGER> | <REAL> | <STRING>  (depending on object type)

      <INTEGER> ::= <SIGN><DIGIT-STRING>
      <REAL> ::= <SIGN><DIGIT-STRING>.<DIGIT-STRING> 

    <OPT-SPACES> ::= <SPACES> | NULL

  <COMMENT> ::= ;<STRING>  (excluding embedded new-lines)

<ALPHA-NUM-STRING> ::= <ALPHA-NUM> | <ALPHA-NUM><ALPHA-NUM-STRING>
<ALPHA-NUM> ::= <DIGIT> | <ALPHA>
<ALPHA> ::= a | ... | z | A | ... | Z
<DIGIT-STRING> ::= <DIGIT> | <DIGIT><DIGIT-STRING>
<DIGIT> ::= 0 | ... | 9
<SIGN> ::= + | - | NULL
<SPACES> ::= <space> | <SPACES><space>
<STRING> ::=  <CHARACTER> | <CHARACTER><STRING>
<CHARACTER> ::= char(0) | char(1) | ... | char(255)

The currently defined objects (used in this database) are listed
in the file "stdfield.c".  The list may be expanded for future
databases, since the grammar does not impose any limit on the number
of objects. The file is simply a repository for "standard" object
definitions.

The single object "end_head" marks the end of the active header and the
remaining unused header space is undefined. A sample header is included
below.

					-- John Garofolo




NIST_1A
   1024
database_id -s5 TIMIT
database_version -s3 1.0
utterance_id -s8 aks0_sa1
channel_count -i 1
sample_count -i 63488
sample_rate -i 16000
sample_min -i -6967
sample_max -i 7710
sample_n_bytes -i 2
sample_byte_format -s2 01
sample_sig_bits -i 16
end_head