Method and apparatus for removing jitter in audio data transmission

A method for obtaining audio frames from a circuit-switched communication link for decoding, the method comprising:

• receiving an audio frame;
• checking if a substitution indicator of said audio frame is set;
• if said substitution indicator is set, providing a redundancy portion of said audio frame to a decoder for decoding;
• and
• if said substitution indicator is not set, providing a primary portion of said audio frame to a decoder for decoding.

An apparatus comprising a jitter buffer, a processor and a memory, said memory containing instructions executable by said processor whereby said apparatus is operative to:

• receive audio frames, each frame comprising a primary portion and a redundancy portion, wherein the redundancy portion comprises a partial redundant copy of a previous frame that is offset by k frames, k being an integer not equal to zero;
• store received audio frames into the jitter buffer;
• determine that a frame n is lost;
• locate in the jitter buffer a frame n+k that comprises the partial redundant copy of the lost frame n;
• create, based on the frame n+k, a substitute frame n′ substituting the lost frame n;
• set a substitution indicator of the substitute frame n′ to indicate that the redundancy portion of the substitute fame n′ should be used in decoding;
• and
• provided the substitute frame n′ for transmission.

An apparatus comprising a processor and a memory, said memory containing instructions executable by said processor whereby said apparatus is operative to:

• receive an audio frame;
• check if a substitution indicator of said audio frame is set;
• provide a redundancy portion of said audio frame to a decoder for decoding if said substitution indicator is set;
• and
• provide a primary portion of said audio frame to a decoder for decoding if said substitution indicator is not set.