Method and Apparatus for Performing Packet Loss or Frame Erasure Concealment

A receiver configured to perform a method for creating output speech samples from arriving packets representing encoded speech, where the method comprises the steps of:

• in a lost frame detector module, determining whether an arrived packet of said packets is unusable because it arrived not as expected;
• when said step of determining concludes that said arrived packet is as expected,
• in a decoder module, decoding said arrived packet to create a plurality of speech samples;
• in a buffer, delaying said speech samples by a delay corresponding to one quarter of longest expected pitch period of said speech, to develop delayed samples;
• and
• sending said delayed samples (sent samples) to an accessible port;
• when said step of determining concludes that said arrived packet is unusable;
• computing a pitch period estimate (PPE), using a number of speech samples that correspond to most recent 20 msec span of said sent samples;
• performing an OLA process on substantially ¼ PPE's worth of most recent of said sent samples with a first OLA segment;
• and
• sending a first concealment segment to said output port;
• where
• said first concealment segment corresponds to substantially 1 PPE's worth of most recent of said sent samples, beginning at the most-recent of said sent samples, and
• said first OLA segment corresponds to substantially ¼ PPE's worth of sent samples that are less recent than said substantially 1 PPE's worth of most recent of said sent samples;
• and
• when said step of determining concludes that said arrived packet follows conclusions relative to N immediately previously arrived packets that they were unusable, and that the arrived packet is as expected (post-erasure packet),
• in said decoder module, decoding said post-erasure packet to create a plurality of speech samples;
• and
• performing an Overlap-Add (OLA) process that combines K initial samples of said speech samples created from said post-erasure packet with K of said sent samples, where K is related to last-computed PPE and value of N.