View Source Upgrading to v1.0.0

Comparing to v0.12, v1.0.0 introduces some minor changes in the public API of the framework. This guide was created to help you migrate to v1.0.0 of membrane_core.


Update membrane_core to v1.0.0

defp deps do
     {:membrane_core, "~> 1.0.0"},

Rename handle_process/4 and handle_write/4 into handle_buffer/4

Names of the callbacks that are used to process buffers have been unified. This applies to:

  • Membrane.Filter.handle_process/4
  • Membrane.Endpoint.handle_write/4
  • Membrane.Sink.handle_write/4

and they became Membrane.Element.WithInputPads.handle_buffer/4

  @impl true
- def handle_process(pad, buffer, ctx, state) do
+ def handle_buffer(pad, buffer, ctx, state) do

Remove handle_process_list/4 and handle_write_list/4 callback

Since v1.0.0, you have to handle every single buffer separately in handle_buffer/4 callback, instead of handling whole list of buffers in this in handle_process_list/4 or handle_write_list/4.

@impl true
- def handle_process_list(pad_ref, buffers_list, ctx, state) do
+ def handle_buffer(pad_ref, buffer, ctx, state) do
@impl true
- def handle_write_list(pad_ref, buffers_list, ctx, state) do
+ def handle_buffer(pad_ref, buffer, ctx, state) do

Change mode and demand_mode options to flow_control in pads' definitions in elements

For input pads, change:

use Membrane.Filter
# or Sink or Endpoint

- def_input_pad :input, mode: :push, ...
+ def_input_pad :input, flow_control: :push, ...

- def_input_pad :input, mode: :pull, demand_mode: :auto, demand_unit: :buffers, ...
+ def_input_pad :input, ...
# (because `flow_control: :auto` is the default whenever available - currently in Filters)
# Note that having `flow_control: :auto` doesn't allow to pass `demand_unit`,
# as it's determined automatically

- def_input_pad :input, mode: :pull, demand_unit: :buffers, ...
+ def_input_pad :input, flow_control: :manual, demand_unit: :buffers, ...

Same goes for output pads:

use Membrane.Filter
# or Source or Endpoint

- def_output_pad :output, mode: :push, ...
+ def_output_pad :output, flow_control: :push, ...

- def_output_pad :output, mode: :pull, demand_mode: :auto,  ...
+ def_output_pad :output, ...

- def_output_pad :output, mode: :pull, ...
+ def_output_pad :output, flow_control: :manual, ...

Check Membrane.Pad.element_spec/0 for details.

Adjust to change in default flow_control (aka. mode/demand_mode) value.

Now, if definition of pad in element does specify type of

Now, the default value of flow_control option in def_input_pad and def_output_pad in Elements is :auto. Until v0.12.9, pads that sepcified neither flow_control, mode nor demand_mode explicitly would have :manual flow_control. Therefore, :manual pads that haven't specified flow_control value, now have to do it explicitly.

- def_output_pad :output, accepted_format: %MyStruct{field: :value}
+ def_output_pad :output, accepted_format: %MyStruct{field: :value}, flow_control: :manual
- def_input_pad :input, accepted_format: %MyStruct{field: :value}, demand_unit: :buffers
+ def_input_pad :input, accepted_format: %MyStruct{field: :value}, demand_unit: :buffers, flow_control: :manual

Moreover, you can remove flow_control: :auto from the pad definitions, if you want to.

- def_input_pad :input, accepted_format: %MyStruct{field: :value}, flow_control: :auto
+ def_input_pad :input, accepted_format: %MyStruct{field: :value}

Remove mode and demand_unit from pads definitions in bins

use Membrane.Bin

- def_input_pad :input, mode: :pull, demand_unit: :buffers, ...
+ def_input_pad :input, ...

- def_output_pad :output, mode: :push, ...
+ def_output_pad :output, ...

Check Membrane.Pad.bin_spec/0 for details.

Don't refer to callback contexts as to structs

Callback contexts are now plain maps instead of structs. So, for example, if you happen to have a match like below, convert it to a match on a map:

@impl true
- def handle_info(message, %Membrane.Element.CallbackContext.Info{pads: pads}, state) do
+ def handle_info(message, %{pads: pads}, state) do

Additionally, there's no direction field anymore in the callback context for handle_pad_added and handle_pad_removed - the direction can be determined by the pad name. All other fields remain the same.

@impl true
- def handle_pad_added(_pad, %{direction: :input}, state) do
+ def handle_pad_added(Pad.ref(:input, _id), _ctx, state) do

Check Membrane.Element.CallbackContext.t/0, Membrane.Bin.CallbackContext.t/0 and Membrane.Pipeline.CallbackContext.t/0 for outline of what can be found in the contexts. Additionally, each callback that provides extra fields in the context, has them mentioned in its docs.

Use Membrane.RCPipeline instead of Membrane.RemoteControlled.Pipeline

- pipeline = Membrane.RemoteControlled.Pipeline.start_link!()
+ pipeline = Membrane.RCPipeline.start_link!()

Same goes for Membrane.RemoteControlled.Message -> Membrane.RCMessage

receive do
- %Membrane.RemoteControlled.Message.Notification{data: data} -> data
+ %Membrane.RCMessage.Notification{data: data} -> data

Use Membrane.Time.as_<unit>(time, :round) instead of Membrane.Time.round_to_<unit>(time)

- Membrane.Time.round_to_milliseconds(time)
+ Membrane.Time.as_milliseconds(time, :round)

There is one exception for round_to_timebase, which changed to divide_by_timebase:

- Membrane.Time.round_to_timebase(time, timebase)
+ Membrane.Time.divide_by_timebase(time, timebase)

Check Membrane.Time for details.

Until v1.0.0-rc0 and v0.12, Membrane has generated start/2, start_link/2, and terminate/1 functions in modules using Membrane.Pipeline, if code developer hadn't done it explicitly. Since v1.0.0, if you want to have these functions implemented in your pipeline module, you have to implement them on your own. Alternatively, you can always call Membrane.Pipeline.start(YourPipelineModule, init_arg, opts), Membrane.Pipeline.start_link(YourPipelineModule, init_arg, opts), and Membrane.Pipeline.terminate(pipeline_pid) from beyond YourPipelineModule without wrapping it into public functions.

Rename :structure option passed to the Membrane.Testing.Pipeline into :spec

import Membrane.ChildrenSpec

spec = 
  child(:source, %Membrane.Testing.Source{some_field: some_arg})
  |> child(:sink), %Membrane.Testing.Sink{another_filed: another_arg}

- pipeline = Membrane.Testing.Pipeline.start_link_supervised(structure: spec)
+ pipeline = Membrane.Testing.Pipeline.start_link_supervised(spec: spec)

Adjust to possibility of receiving end of stream on pads, that haven't received start of stream yet.

Since v1.0.0, Membrane will execute Membrane.Element.WithInputPads.handle_end_of_stream/3 for all pads, including these having start_of_stream?: false.