AirPlay.Source (AirPlay v0.2.0)

Decode a library track to the PCM format AirPlay/RAOP wants: 44.1 kHz, 16-bit, stereo, little-endian, via ffmpeg. Returns the raw interleaved s16le bytes, which AirPlay.Alac chops into 352-sample frames.

Summary

Functions

frames(pcm, frames \\ 352)

Split PCM into frames-sample stereo chunks (last one zero-padded).

pcm(path)

Decode path to interleaved s16le stereo @44.1kHz, or {:error, reason}.

stream_args(path, opts \\ [])

Build the ffmpeg argument list for streaming decode (used by AirPlay.Decoder), emitting interleaved s16le stereo @44.1kHz on stdout.

Functions

frames(pcm, frames \\ 352)

@spec frames(binary(), pos_integer()) :: [binary()]

Split PCM into frames-sample stereo chunks (last one zero-padded).

pcm(path)

@spec pcm(String.t()) :: {:ok, binary()} | {:error, term()}

Decode path to interleaved s16le stereo @44.1kHz, or {:error, reason}.

stream_args(path, opts \\ [])

@spec stream_args(
  String.t(),
  keyword()
) :: [String.t()]

Build the ffmpeg argument list for streaming decode (used by AirPlay.Decoder), emitting interleaved s16le stereo @44.1kHz on stdout.

Options:

:start_seconds — input seek offset (fast -ss before -i)

-re makes ffmpeg read its input at native rate, so it produces PCM at ~1× real time rather than as fast as it can decode — that's the backpressure that keeps the decoder's buffer (and the BEAM mailbox) bounded for long files.