Apparatus and method realizing improved concepts for TCX LTP

An apparatus for transform coded excitation decoding an encoded audio signal to acquire a reconstructed audio signal, wherein the apparatus is configured to receive a plurality of frames, and wherein the apparatus comprises:

• a long-term prediction unit for conducting long-term prediction, comprising:
• a delay buffer for storing audio signal samples of the decoded audio signal,
• a sample selector for selecting a plurality of selected audio signal samples from the audio signal samples being stored in the delay buffer, and
• a sample processor for processing the selected audio signal samples to acquire reconstructed audio signal samples of the reconstructed audio signal,
• wherein the sample selector is configured to select, if a current frame is received by the apparatus and if the current frame being received by the apparatus is not corrupted, the plurality of selected audio signal samples from the audio signal samples being stored in the delay buffer depending on a pitch lag information being comprised by the current frame, and
• wherein the sample selector is configured to select, if the current frame is not received by the apparatus or if the current frame being received by the apparatus is corrupted, the plurality of selected audio signal samples from the audio signal samples being stored in the delay buffer depending on a pitch lag information being comprised by another frame being received previously by the apparatus,
• wherein the sample selector is configured to acquire the reconstructed audio signal samples by rescaling the selected audio signal samples depending on a modified transform coded excitation long term prediction decoder gain, wherein the modified transform coded excitation long term prediction decoder gain is defined according to the formula:
• gain=gain_past*damping;
• wherein gain is the modified transform coded excitation long term prediction decoder gain,
• wherein the sample selector is configured to set gain_past to gain after gain has been calculated, wherein gain_past is the transform coded excitation long-term prediction decoder gain applied in the previous frame, and
• wherein damping is a real value with 0≤damping≤1.