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 1024 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: ::= | | | ::= ::= | ::= | ::= _ | _ ::= - | - | - ::= i ::= r ::= s ::= | | (depending on object type) ::= ::= . ::= | NULL ::= ; (excluding embedded new-lines) ::= | ::= | ::= a | ... | z | A | ... | Z ::= | ::= 0 | ... | 9 ::= + | - | NULL ::= | ::= | ::= 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
