A transmitting apparatus generates an audiovisual content item data stream (e.g. transport stream) comprising a plurality of individual audiovisual data streams with audiovisual components for the content item. A generator (301-307) generates a first stream comprising both mandatory audio data and replaceable audio data for the audio representation where the replaceable audio data being data can be replaced by alternative audio data. A combiner (309) includes the resulting stream into the content item data stream. A receiving apparatus includes an extractor (403) which extracts the mandatory audio data from the received stream. A replacer (415) may replace the replaceable audio data by alternative audio data and an output (415) can generate an audio signal from the mandatory and alternative audio data. The approach may specifically provide an improved and more flexible data stream for audiovisual content.