you should use our FFmpeg SWResample plugin. The docs contain an example of a thing similar to what you want to do, except for the fact that the input is a file instead of a in-memory binary. Let me know if you have any trouble!

Thanks so much both, that’s super useful. I can confirm that the resampled audio file plays as intended and the LiveBook no longer crashes

Will have a go at writing a BinarySrc plugin now

1. Unfortunately we don’t have a plugin that allows a binary input or output, however it would be very simple to implement if you read the file plugin’s code, probably ~30-40 lines of code.
2. The aborted state is a result of a crash of the pipeline. I don’t know why the error isn’t present in the cell output. There are two causes to the pipeline crashing. The first one is that as soon as you define a callback (such as handle_element_end_of_stream) for one input case, the automatic implementation disappears, so when :file_src returns end of stream, membrane tries to call Resampling.Pipeline.handle_element_end_of_stream(:file_src, _, _, _) and fails to find an implementation. The fix for this is simple: you need to define

   ...
   
   @impl true
     def handle_element_end_of_stream(:file_sink, _pad, _ctx_, _state) do
       {[playback: :stopped], nil}
     end
   
   @impl true
   def handle_element_end_of_stream(_child, _pad, _ctx, _state) do
     {[], nil}
   end
   
   ...
   

   The second problem is returning the playback: :stopped action, which doesn’t exist in membrane core v0.11. You should return terminate: :normal instead.
3. Functions that start a pipeline return {:ok, supervisor_pid, pipeline_pid} in case of success, because the pipeline is always spawned under a dedicated supervisor. The supervisor never restarts the pipeline, but it makes sure that the pipeline and its children terminate properly.
4. The guide you’re referring to uses membrane core v0.7, and is unfortunately out of date : (. The play() function was replaced with returning the playback: :playing action, which you did in your handle_init. I’m sorry the guides are outdated, we decided it would be better for now to focus on releasing core 1.0 and rewrite the old guides after that, since then the API will not change every couple months.
5. Try playing the files after resampling, since as I mentioned, they might be corrupted due to a bug we are currently having in out swresample plugin ;( We’re working on fixing it as soon as possible!

Hope this helps, let me know if you need anything else!