An audio encoder configured to encode an audio signal to generate a bitstream having E-AC-3 format, including by determining a first control parameter indicative of an allocation of available mantissa bits for quantized audio content of the signal. The encoder is configured to perform transcoding simulation to determine a second control parameter in a manner based at least in part on statistical analysis of results of E-AC-3 bit allocation processing of audio data assuming a first target data rate, and of AC-3 bit allocation processing of the data assuming a second target data rate, and to include the second control parameter in the bitstream for use by a converter to convert the bitstream into a second bitstream having AC-3 format at the second target data rate. Other aspects are converters configured to perform transcoding on a bitstream using such a second control parameter, and methods performed by any embodiment of the inventive encoder or converter.