Method for frame-wise combined decoding and rendering of a compressed HOA signal and apparatus for frame-wise combined decoding and rendering of a compressed HOA signal

An apparatus for frame-wise combined decoding and rendering an input signal comprising a compressed HOA signal to obtain loudspeaker signals, wherein a HOA rendering matrix (D) according to a given loudspeaker configuration is computed and used, the apparatus comprising a processor and

• a memory storing instructions that, when executed, cause the apparatus to perform for each frame
• demultiplexing the input signal into a perceptually coded portion and a side information portion;
• perceptually decoding in a perceptual decoder the perceptually coded portion, wherein perceptually decoded signals (z1(k), . . . , zI(k)) are obtained that represent two or more components of at least two different types that require a linear operation for reconstructing HOA coefficient sequences, wherein no HOA coefficient sequences are reconstructed, and wherein
• for components of a first type a fading of individual coefficient sequences (ĈAMB(k), CDIR(k)) is not required for said reconstructing, and
• for components of a second type a fading of individual coefficient sequences (CPD(k), CVEC(k)) is required for said reconstructing;
• decoding in a side information decoder the side information portion, wherein decoded side information is obtained;
• applying linear operations that are individual for each frame, to components of the first type to generate first loudspeaker signals (ŴAMB(k), ŴDIR(k));
• determining, according to the side information and individually for each frame, for each component of the second type three different linear operations, with a first different linear operation (APD,OUT,IA(k), APD,IN,IA(k), AVEC,OUT,IA (k), AVEC,IN,IA(k)) being for coefficient sequences that according to the side information require no fading, a second different linear operation (APD,OUT,D(k), APD,IN,D(k), AVEC,OUT,D (k), AVEC,IN,D(k)) being for coefficient sequences that according to the side information require fading-in, and a third different linear operation (APD,OUT,E(k), APD,IN,E(k), AVEC,OUT,E(k), AVEC,IN,E(k)) being for coefficient sequences that according to the side information require fading-out;
• generating from the perceptually decoded signals belonging to each component of the second type three versions, wherein a first version (YPD,OUT,IA(k), YPD,IN,IA(k), YVEC,OUT,IA(k), YVEC,IN,IA(k)) comprises the original signals of the respective component, which are not faded, a second version (YPD,OUT,D(k), YPD,IN,D(k), YVEC,OUT,D(k), YVEC,IN,D(k)) of signals is obtained by fading-in the original signals of the respective component, and a third version (YPD,OUT,E(k), YPD,IN,E(k), YVEC,OUT,E(k), YVEC,IN,E(k)) of signals is obtained by fading out the original signals of the respective component;
• applying to each of said first, second and third versions of said perceptually decoded signals the respective linear operation and superimposing the results to generate second loudspeaker signals (ŴPD(k), ŴVEC(k));
• and
• adding the first and second loudspeaker signals (ŴAMB(k), ŴPD(k), ŴDIR(k), ŴVEC(k)), wherein the loudspeaker signals (Ŵ(k)) of a decoded input signal are obtained.