Audio decoder comprising: an audio decoding core configured to reconstruct an audio signal , in units of audio frames of the audio signal, from a sequence of payload packets of an audio data stream , wherein each of the payload packets belongs to a respective one of a sequence of access units into which the audio data stream is partitioned, wherein each access unit is associated with a respective one of the audio frames; and an audio truncator configured to be responsive to a truncation unit packet (42; 58; 114) which is inserted, within a predetermined access unit, into the audio data stream, and comprises a packet type index indicating that the truncation unit packet is a truncation unit packet, a truncation length element indicating a temporal length of an end portion of an audio frame associated with the predetermined access unit in units of individual audio samples, or in n-tuples of consecutive audio samples, and a flag indicating whether the predetermined access unit has actually been used as a splice-out point or not; and a leading/trailing indicator indicating whether the temporal length is measured from a leading end or a trailing end of the audio frame towards an inner of the audio frame so as to check whether the flag is set and if so, truncate the audio frame so as to discard, in playing out the audio signal, the end portion indicated to be discarded in playout by the truncation unit packet, and if not, play out the audio frame completely. an audio decoding core configured to reconstruct an audio signal , in units of audio frames of the audio signal, from a sequence of payload packets of an audio data stream , wherein each of the payload packets belongs to a respective one of a sequence of access units into which the audio data stream is partitioned, wherein each access unit is associated with a respective one of the audio frames; and an audio truncator configured to be responsive to a truncation unit packet (42; 58; 114) which is inserted, within a predetermined access unit, into the audio data stream, and comprises a packet type index indicating that the truncation unit packet is a truncation unit packet, a truncation length element indicating a temporal length of an end portion of an audio frame associated with the predetermined access unit in units of individual audio samples, or in n-tuples of consecutive audio samples, and a flag indicating whether the predetermined access unit has actually been used as a splice-out point or not; and a leading/trailing indicator indicating whether the temporal length is measured from a leading end or a trailing end of the audio frame towards an inner of the audio frame a packet type index indicating that the truncation unit packet is a truncation unit packet, a truncation length element indicating a temporal length of an end portion of an audio frame associated with the predetermined access unit in units of individual audio samples, or in n-tuples of consecutive audio samples, and a flag indicating whether the predetermined access unit has actually been used as a splice-out point or not; and a leading/trailing indicator indicating whether the temporal length is measured from a leading end or a trailing end of the audio frame towards an inner of the audio frame so as to check whether the flag is set and if so, truncate the audio frame so as to discard, in playing out the audio signal, the end portion indicated to be discarded in playout by the truncation unit packet, and if not, play out the audio frame completely. <EOS>