Streaming audio only gives aacDecoder_DecodeFrame errors

[formatc1702]

Running RPiPlay with:

./rpiplay -n PiPlay -a analog

Result:

• Regular AirPlay streaming (audio+video) works.
• Attempting to stream only audio (as per this guide) leads to a stream of errors:

  Accepted IPv4 client on socket 15
  Local: ...
  Remote: ...
  Accepted IPv4 client on socket 17
  Local: ...
  Remote: ...
  Found an unknown parameter: volume
  raop_rtp starting audio
  Got metadata of 143 bytes
  aacDecoder_DecodeFrame error : 0x4002
  aacDecoder_DecodeFrame error : 0x400c
  aacDecoder_DecodeFrame error : 0x4002
  aacDecoder_DecodeFrame error : 0x4002
  aacDecoder_DecodeFrame error : 0x4002
  aacDecoder_DecodeFrame error : 0x4002
  aacDecoder_DecodeFrame error : 0x400c
  aacDecoder_DecodeFrame error : 0x4002
  ...

  For the last digit, I've seen 2, 6 and c, no other values.

• Running with additional -vr dummy flag (since I don't care about video), results in successful connection and no errors, but no audio output either.

Setup:

• Raspberry Pi 1 (yes, don't have anything else to test now)
• Raspbian 10 (buster)
• RPiPlay 1.2
• Client: MacBook Pro (Retina, 13-inch, Late 2013) / MacOS 10.15.7 (19H2)

Am I doing something wrong? Does something need to be changed? Thanks!

[pallas]

Thanks for the thorough bug report. Those error codes correspond to AAC_DEC_PARSE_ERROR, AAC_DEC_INVALID_CODE_BOOK, & AAC_DEC_TNS_READ_ERROR, which means the received bitstream is likely corrupt. I don't know if that's happening in the sender or in RPiPlay, but I can attempt to try this setup over the weekend, however I assume it's a duplicate of Issue #2. Apple uses ALAC for audio-only mirroring, while screen mirroring uses AAC.

[formatc1702]

Thanks for the quick reply and interesting insight! I shall try Shairplay later today. If it turns out this is a duplicate of #2, let's close this issue. Will report back.

[formatc1702]

Update: After messing around with Shairplay without success, I stumbled upon shairport-sync that does just what I want, and works wonderfully. Thanks to the RPiPlay folks anyway! Have a good one.