Audio decoder 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 includes associated encoded audio sample values, the audio decoder comprising: a determiner configured to determine whether a frame of the encoded audio data is a special frame (42, 80) comprising encoded audio sample values associated with the special frame (42, 80) 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 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 (42, 80) if the special frame is the first frame upon start-up of the decoder; and an initializer configured to initialize the decoder if the determiner determines that the frame is a special frame, wherein initializing the decoder comprises decoding the encoded audio sample values included in the additional information before decoding the encoded audio sample values associated with the special frame (42, 80), wherein the initializer is configured to switch the audio decoder from a current codec configuration to a different codec configuration if the determiner determines that the frame is a special frame (42, 80) and if the audio sample values of the special frame have been encoded using the different codec configuration, and wherein the decoder is configured to decode the special frame (42, 80) using the current codec configuration and to discard the additional information if the determiner determines that the frame is a special frame (42, 80) and if the audio sample values of the special frame have been encoded using the current codec configuration. a determiner configured to determine whether a frame of the encoded audio data is a special frame (42, 80) comprising encoded audio sample values associated with the special frame (42, 80) 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 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 (42, 80) if the special frame is the first frame upon start-up of the decoder; and an initializer configured to initialize the decoder if the determiner determines that the frame is a special frame, wherein initializing the decoder comprises decoding the encoded audio sample values included in the additional information before decoding the encoded audio sample values associated with the special frame (42, 80), wherein the initializer is configured to switch the audio decoder from a current codec configuration to a different codec configuration if the determiner determines that the frame is a special frame (42, 80) and if the audio sample values of the special frame have been encoded using the different codec configuration, and wherein the decoder is configured to decode the special frame (42, 80) using the current codec configuration and to discard the additional information if the determiner determines that the frame is a special frame (42, 80) and if the audio sample values of the special frame have been encoded using the current codec configuration.