Patent ID: 7433815

Claim:
A method for transcoding a source codec bitstream in a source codec format to a destination variable-rate codec bitstream in a destination variable-rate codec format, the method comprising: unpacking the source codec bitstream to at least one or more source voice parameters; interpolating the one or more source voice parameters to one or more interpolated voice parameters if a difference exists between at least one of a source frame size and a destination frame size or a source subframe size and a destination subframe size or a source sampling rate and a destination sampling rate; classifying a frame class based upon the one or more source voice parameters or the one or more interpolated voice parameters, wherein the frame class is selected from three or more frame classes, wherein classifying the frame class comprises: selecting one or more voice parameters from the one or more source voice parameters or the one or more interpolated voice parameters; using a previously stored state information; performing frame classification to produce the frame class; outputting the frame class; and updating the previously stored state information for use in classifying one or more future frames; determining a rate from at least one of the one or more source voice parameters, the one or more interpolated voice parameters, the frame class, and one or more external control commands, wherein the rate is selected from three or more rates associated with the destination variable-rate codec format; mapping the one or more source voice parameters or the one or more interpolated voice parameters to one or more mapped voice parameters; and packing the one or more mapped voice parameters into the destination variable-rate codec bitstream.