Position-Dependent Hybrid Domain Packet Loss Concealment

摘要

The present document relates to audio signal processing in general, and to the concealment of artifacts that results from loss of audio packets during audio transmission over a packet-switched network, in particular. A method (200) for concealing one or more consecutive lost packets (412, 413) is described. A lost packet (412) is a packet which is deemed to be lost by a transform-based audio decoder. Each of the one or more lost packets (412, 413) comprises a set of transform coefficients (313). A set of transform coefficients (313) is used by the transform-based audio decoder to generate a corresponding frame (412, 413) of a time domain audio signal. The method (200) comprises determining (205) for a current lost packet (412) of the one or more lost packets (412, 413) a number of preceding lost packets from the one or more lost packets (313); wherein the determined number is referred to as a loss position. Furthermore, the method comprises determining a packet loss concealment, referred to as PLC, scheme based on the loss position of the current packet; and determining (204, 207, 208) an estimate of a current frame (422) of the audio signal using the determined PLC scheme (204, 207, 208); wherein the current frame (422) corresponds to the current lost packet (412).

主权项

1. A method comprising
obtaining, by an audio processor, a packet including a set of modified discrete cosine transform (MDCT) coefficients associated with a frame that includes time-domain samples of an audio signal; determining, by the audio processor, that the received packet includes one or more errors; generating, by the audio processor, estimated MDCT coefficients to replace the received set of MDCT coefficients, the estimated MDCT coefficients being based on corresponding MDCT coefficients associated with a last received packet that directly precedes the received packet in a sequence of packets; assigning, by the audio processor, signs to a first subset of the estimated MDCT coefficients to be equal to corresponding signs of the corresponding MDCT coefficients of the last received packet, the first subset of estimated MDCT coefficients being associated with tonal bands of the last received packet; randomly assigning, by the audio processor, signs to a second subset of the estimated MDCT coefficients, wherein the second subset of estimated MDCT coefficients are associated with non-tonal bands of the last received packet; generating, by the audio processor, a concealment packet based on the set of estimated MDCT coefficients; and replacing, by the audio processor, the received packet with the concealment packet.