Audio decoder, apparatus for generating encoded audio output data and methods permitting initializing a decoder

An apparatus for generating a bit stream of encoded audio data representing a sequence of audio sample values of an audio signal, wherein the bit stream of encoded audio data comprise a plurality of frames, wherein each frame comprises associated encoded audio sample values, wherein the apparatus comprises:

• a special frame provider configured to provide at least one of the frames as a special frame, the special frame comprising encoded audio sample values associated with the special frame and additional information, wherein the additional information comprise encoded audio sample values of a number of frames preceding the special frame, wherein the encoded audio sample values of the preceding frames are encoded using the same codec configuration as the special frame, and wherein the number of preceding frames, corresponding to pre-roll frames, corresponds to the number of frames needed by a decoder to build up the full signal during start-up of the decoder so as to be in a position to decode the audio sample values associated with the special frame if the special frame is the first frame upon start-up of the decoder;
• and
• an output configured to output the bit stream of encoded audio data,
• wherein the encoded audio data comprise a plurality of segments, wherein each segment is associated with one of a plurality of portions of the sequence of audio sample values and comprises a plurality of frames, wherein the special frame adder is configured to add a special frame at the beginning of each segment irrespective of whether the codec configuration changes or not.

A method for decoding a bit stream of encoded audio data, wherein the bit stream of encoded audio data represents a sequence of audio sample values and comprises a plurality of frames, wherein each frame comprises associated encoded audio sample values, comprising:

• determining whether a frame of the encoded audio data is a special frame comprising encoded audio sample values associated with the special frame and additional information, wherein the additional information comprise encoded audio sample values of a number of frames preceding the special frame, wherein the encoded audio sample values of the preceding frames are encoded using the same codec configuration as the special frame, wherein the number of preceding frames, corresponding to pre-roll frames, corresponds to the number of frames needed by a decoder to build up the full signal during start-up of the decoder so as to be in a position to decode the audio sample values associated with the special frame if the special frame is the first frame upon start-up of the decoder;
• initializing the decoder if it is determined that the frame is a special frame, wherein the initializing comprises decoding the encoded audio sample values comprised by the additional information before decoding the encoded audio sample values associated with the special frame;
• switching the audio decoder from a current codec configuration to a different codec configuration if it is determined that the frame is a special frame and if the audio sample values of the special frame have been encoded using the different codec configuration;
• and
• decoding the special frame using the current codec configuration and discarding the additional information if it is determined that the frame is a special frame and if the audio sample values of the special frame have been encoded using the current codec configuration.

A method for generating a bit stream of encoded audio data representing a sequence of audio sample values of an audio signal, wherein the bit stream of encoded audio data comprise a plurality of frames, wherein each frame comprises associated encoded audio sample values, comprising:

• providing at least one of the frames as a special frame, the special frame comprising encoded audio sample values associated with the special frame and additional information, wherein the additional information comprise encoded audio sample values of a number of frames preceding the special frame, wherein the encoded audio sample values of the preceding frames are encoded using the same codec configuration as the special frame, and wherein the number of preceding frames, corresponding to pre-roll frames, corresponds to the number of frames needed by the decoder to build up the full signal during start-up of the decoder so as to be in a position to decode the audio sample values associated with the special frame if the special frame is the first frame upon start-up of the decoder;
• and
• generating the bit stream by concatenating the special frame and the other frames of the plurality of frames,
• wherein the encoded audio data comprise a plurality of segments, wherein each segment is associated with one of a plurality of portions of the sequence of audio sample values and comprises a plurality of frames, wherein a special frame is added at the beginning of each segment irrespective of whether the codec configuration changes or not.