Carsten Gross: > Hello, > > AAC audio streams offer the possibility of transmitting additional binary > data with the audio data. The corresponding element is called a "data > stream element" (DSE). On the new ARD satellite audio transponder on > Astra 19.2E, this is used by NDR, for example, to transmit RDS (Radio > Data System). The audio format used is AAC-LATM. > > In the current ffmpeg git code, DSE are skipped. I have included a > HexDump of the DSE data in libavcodec/aacdec_template.c (by changing > skip_data_stream_element()) for testing and in the Hexdump I see exactly > the data I would like to get out of the audio data stream into my > application "ts2shout" with the help of ffmpeg libavcodec. > > If I want to implement DSE support, what is the right "ffmpeg-"way to > provide this binary data embedded in the audio frames to a user > application? Metadata seems to be more for "static" properties of files > and it is text only. > > Would using "AVFrameSideData" be the right method to transfer the data > to the user application? Is there a generic data type, or would I have > to define a new one in AVAudioServiceType, regarding that it is possible > to have more then one DSE in one audio frame? My plan would be to later > pass the individual AAC frames to libavcodec for decoding (like it is > described in the example in doc/examples/decode_audio.c) and possibly > only evaluate the respective DSE. > Using frame side data (or also packet side data -- a matching packet side data would be needed if one wanted to preserve this data when reencoding/encoding from scratch; this would also allow to write a bitstream filter to extract this without decoding) is the right way to do this. I do not see any side data type that matches your usecase, so you will probably create new ones.
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