Speech compression

DETAILED DESCRIPTION In accordance with this invention, generally stated, a novel compression scheme is employed for compression of audio data to attain an approximate 2:1 reduction of sample data.
Data reduction is accomplished by determining a gain factor for a preselected length of data sets.
In the embodiment illustrated, the preselected data length comprises sixty-four sets of data, each set comprissing eight bits.
The maximum amplitude for each of the sixty-four data sets is determined and this maximum amplitude is encoded to provide a gain factor.
Thereafter, the gain factor is divided into, i.
e.
removed, from the corresponding sixty-four sets of data to obtain a compressed four bit set of sample data for each one of the sixty-four data sets.
The compressed sample data set is stored for use as necessary in a suitable storage medium.
Recomposition is accomplished by multiplying the gain factor of the sixty-four sample set by each sample in that set.
The preferred design for the memory employed with the compression scheme of this invention is a series of charge coupled device memories, which can be thought of as a rotating memory or a recirculating shift register.
Magnitude data is stored in a smaller memory and information is withdrawn from the memories as required,.
The particular embodiment enables up to two hundred and fifty-six messages to be played simultaneously.
Any combination, from all messages being the same to all messages being different within the range of two hundred and fifty-six accesses is possible.