@callback handle_buffer(
  pad :: Membrane.Pad.ref(),
  buffer :: Membrane.Buffer.t(),
  context :: Membrane.Element.CallbackContext.t(),
  state :: Membrane.Element.state()
) ::
  {[
     Membrane.Element.Action.common_actions()
     | Membrane.Element.Action.stream_actions()
     | Membrane.Element.Action.forward()
   ], Membrane.Element.state()}

Callback that is called when buffer should be processed by the Element.

For pads in pull mode it is called when buffer have been demanded (by returning :demand action from any callback).

For pads in push mode it is invoked when buffer arrive.

@callback handle_end_of_stream(
  pad :: Membrane.Pad.ref(),
  context :: Membrane.Element.CallbackContext.t(),
  state :: Membrane.Element.state()
) ::
  {[
     Membrane.Element.Action.common_actions()
     | Membrane.Element.Action.stream_actions()
     | Membrane.Element.Action.forward()
   ], Membrane.Element.state()}

Callback invoked when the previous element has finished processing via the pad, and it cannot be used anymore.

@callback handle_start_of_stream(
  pad :: Membrane.Pad.ref(),
  context :: Membrane.Element.CallbackContext.t(),
  state :: Membrane.Element.state()
) ::
  {[
     Membrane.Element.Action.common_actions()
     | Membrane.Element.Action.stream_actions()
     | Membrane.Element.Action.forward()
   ], Membrane.Element.state()}

Callback invoked when element receives Membrane.Event.StartOfStream event.

@callback handle_stream_format(
  pad :: Membrane.Pad.ref(),
  stream_format :: Membrane.StreamFormat.t(),
  context :: Membrane.Element.CallbackContext.t(),
  state :: Membrane.Element.state()
) ::
  {[
     Membrane.Element.Action.common_actions()
     | Membrane.Element.Action.stream_actions()
     | Membrane.Element.Action.forward()
   ], Membrane.Element.state()}

Callback invoked when Element is receiving information about new stream format for given pad.

In filters stream format is forwarded through all output pads by default.

Context passed to this callback contains additional field :old_stream_format.