The default for parameter files is native HTK format. However, HTK tools also support the Entropic Esignal format for both input and output. Esignal replaces the Entropic ESPS file format. To ensure compatibility Entropic provides conversion programs from ESPS to ESIG and vice versa.
To indicate that a source file is in Esignal format the configuration variable SOURCEFORMAT should be set to ESIG. Alternatively, -F ESIG can be specified as a command-line option. To generate Esignal format output files, the configuration variable TARGETFORMAT should be set to ESIG or the command line option -O ESIG should be set.
ESIG files consist of three parts: a preamble, a sequence of field specifications called the field list and a sequence of records. The preamble and the field list together constitute the header. The preamble is purely ASCII. Currently it consists of 6 information items that are all terminated by a new line. The information in the preamble is the following:
line 1 - identification of the file formatAll ESIG files that are output by HTK programs contain the following global fields:line 2 - version of the file format
line 3 - architecture (ASCII, EDR1, EDR2, machine name)
line 4 - preamble size (48 bytes)
line 5 - total header size
line 6 - record size
zerocThe data segments of the ESIG files have exactly the same format as the the corresponding HTK files. This format was described in the previous section.energy
delta
delta_zeroc
delta_energy
accs
accs_zeroc
accs_energy
HTK can only input parameter files that have a valid parameter kind as value of the header field parmKind. If this field does not exist or if the value of this field does not contain a valid parameter kind, the file is rejected. After the header has been read the file is treated as an HTK file.