1. 10 Jul, 2020 1 commit
  2. 03 Jul, 2019 1 commit
    • Andre Guedes's avatar
      avtp: Introduce AAF payloader element · 1e985f02
      Andre Guedes authored
      This patch introduces the AVTP Audio Format (AAF) payloader element from
      the AVTP plugin. The element inputs audio raw data and outputs AVTP
      packets (aka AVTPDUs), implementing a typical protocol payloader element
      from GStreamer.
      AAF is one of the available formats to transport audio data in an AVTP
      system. AAF is specified in IEEE 1722-2016 section 7 and provides two
      encapsulation mode: PCM and AES3. This patch implements PCM
      encapsulation mode only.
      The AAF payloader working mechanism consists of building the AAF header,
      prepending it to the GstBuffer received on the sink pad, and pushing the
      buffer downstream. Payloader parameters such as stream ID, maximum
      transit time, time uncertainty, and timestamping mode are passed via
      element properties. AAF doesn't support all possible sample format and
      sampling rate values so the sink pad caps template from the payloader is
      a subset of audio/x-raw. Additionally, this patch implements only
      "normal" timestamping mode from AAF. "Sparse" mode should be implemented
      in future.
      Upcoming patches will introduce other AVTP payloader elements that will
      have some common code. For that reason, this patch introduces the
      GstAvtpBasePayload abstract class that implements common payloader
      functionalities, and the GstAvtpAafPay class that extends the
      GstAvtpBasePayload class, implementing AAF-specific functionalities.
      The AAF payloader element is most likely to be used with the AVTP sink
      element (to be introduced by a later patch) but it could also be used
      with UDP sink element to implement AVTP over UDP as described in IEEE
      1722-2016 Annex J.
      This element was inspired by RTP payloader elements.