Abstract: An audio-on-demand communication system provides real-time playback of audio data transferred via telephone lines or other communication links. One or more audio servers include memory banks which store compressed audio data. At the request of a user at a subscriber PC, an audio server transmits the compressed audio data over the communication link to the subscriber PC. The subscriber PC receives and decompresses the transmitted audio data in less than real-time using only the processing power of the CPU within the subscriber PC. According to one aspect of the present invention, high quality audio data compressed according to lossless compression techniques is transmitted together with normal quality audio data. According to another aspect of the present invention, metadata, or extra data, such as text, captions, still images, etc., is transmitted with audio data and is simultaneously displayed with corresponding audio data.

Abstract: A method and system for mitigating and compensating for loss of digital audio data transmitted as a stream of packets to a client (30). A server (10) compresses digital audio data corresponding to a digitized analog audio signal. The compressed data are divided into N frames of data per packet. The server interleaves the frames, producing interleave packets of up to order N. The interleave operation minimizes the effect of any lost packet when the interleave packets are received, deinterleaved, and converted to an analog signal that is played on a speaker at the client. Lost frames are replaced using the data from frames that are received. As a further aspect, the frames can be scrambled at the server by applying a permutation function F that depends upon the packet number (PN) and a Key value. At the client, an inverse permutation function F.sup.-1 is applied to unscramble the frames.