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ReadiVoice Administration & Maintenance Guide
176 Proprietary & Confidential
Indexed WAVE File Specifications
In Polycom’s indexed WAVE files, the Data chunk consists of a set of
individual sound files that are concatenated together. An Index chunk enables
Polycom applications to locate the individual sound clips and quickly piece
them together to play phrases, numbers, dates, and so forth. The sound clips
can be common words, digits, alphabetic letters, or even short phrases.
An indexed WAVE file has:
• The chunk identifier, which is the four-character code
RIFF
.
• The size of the data member chunk, a
DWORD
(4-byte integer). The size is
everything after the first eight bytes (the chunk identifier and the size
DWORD
itself).
• The data member is the largest portion of the file. It consists of:
— A
DWORD
that specifies the form type of the chunk (in this case
WAVE
).
— A Format subchunk that describes the data (sample rate, bit
resolution, type of compression, and so forth).
— A Language chunk identifying the language of the sound clips.
— An Index chunk containing all of the offset information. The Index
chunk contains:
» The size (
DWORD
) of the Index chunk.
» The number (
DWORD
) of sound clips in the WAVE file.
» The offset location (
DWORD
) and length in bytes (
DWORD
) of each
sound clip in the file.
— The Data subchunk contains the actual sampled audio data, or sound
clips. These are the data subchunks pulled out of individual WAVE
files and concatenated here.
The specifications for these chunks use Microsoft’s RIFF notation. Look up
RIFF notation on the Microsoft Developer Network
(www.msdn.microsoft.com).
Language Chunk
The Language chunk identifies the language associated with the indexed
WAVE file. This lets applications using the file apply the appropriate
grammar, where required, for building number or date phrases correctly in
that language. An indexed WAVE file can have only one language identifier.
Only predefined indexed WAVE files use the language field. You specify other
languages using the appropriate predefined key file. Supported languages are:
• CHINESE
• ENGLISH
• FRENCH