Decoder and decoding method selecting an error concealment mode, and encoder and encoding method

A system for decoding a frame to reconstruct a signal portion of a signal, wherein the system comprises:

• an encoder for encoding a signal portion of a signal within a frame, and
• a decoder for decoding the frame to reconstruct the signal portion of the signal,
• wherein the decoder is configured for decoding the frame to reconstruct the signal portion of the signal, wherein the signal portion is encoded within the frame, wherein the frame comprises a bitstream payload and two or more redundancy bits, wherein the bitstream payload comprises a plurality of payload bits, wherein each of the payload bits exhibits a position within the bitstream payload, wherein the decoder comprises:
• a channel decoding module, being configured to detect, depending on the two or more redundancy bits, whether the bitstream payload comprises one or more corrupted bits being one or more of the payload bits that are distorted or that are likely to be distorted,
• a source decoding module,
• wherein, if the channel decoding module has not detected any corrupted bits within the bitstream payload, the source decoding module is configured to decode the bitstream payload without conducting error concealment to reconstruct the signal portion,
• wherein, if the channel decoding module has detected the one or more corrupted bits within the bitstream payload, the source decoding module is configured to select a selected error concealment mode of two or more error concealment modes depending on the position of at least one of the one or more corrupted bits within the bitstream payload and depending on a signal characteristic of the signal portion of the signal, and is configured to conduct error concealment depending on the selected error concealment mode to reconstruct the signal portion;
• wherein the bitstream payload is partitioned into a first part of the plurality of payload bits of the bitstream payload, and into a second part of the plurality of payload bits of the bitstream payload;
• wherein the bitstream payload is a current bitstream payload;
• wherein, if the first part of the current bitstream payload does not comprise any of the one or more corrupted bits, the source decoding module is configured to select a full frame loss concealment mode of the two or more error concealment modes as the selected error concealment mode, if a highest spectral line among a plurality of spectral lines of a current audio signal portion exhibits a frequency being smaller than or equal to a threshold frequency.

A method for decoding a frame to reconstruct a signal portion of a signal, wherein the signal portion is encoded within the frame, wherein the frame comprises a bitstream payload and two or more redundancy bits, wherein the bitstream payload comprises a plurality of payload bits, wherein each of the payload bits exhibits a position within the bitstream payload, wherein the method comprises:

• detecting, depending on the two or more redundancy bits, whether the bitstream payload comprises one or more corrupted bits being one or more of the payload bits that are distorted or that are likely to be distorted,
• if no corrupted bits have been detected within the bitstream payload, decoding the bitstream payload without conducting error concealment to reconstruct the signal portion, and
• if one or more corrupted bits have been detected within the bitstream payload, selecting a selected error concealment mode of two or more error concealment modes depending on the position of at least one of the one or more corrupted bits within the bitstream payload and depending on a signal characteristic of the signal portion of the signal, and conducting error concealment depending on the selected error concealment mode to reconstruct the signal portion;
• wherein the bitstream payload is partitioned into a first part of the plurality of payload bits of the bitstream payload, and into a second part of the plurality of payload bits of the bitstream payload;
• wherein the bitstream payload is a current bitstream payload;
• wherein, if the first part of the current bitstream payload does not comprise any of the one or more corrupted bits, the method comprises selecting a full frame loss concealment mode of the two or more error concealment modes as the selected error concealment mode, if a highest spectral line among a plurality of spectral lines of a current audio signal portion exhibits a frequency being smaller than or equal to a threshold frequency.