Combining frame and packets transformers

[k-wasniowski]

What should be behavior of the algorithm if user would like to combine frame and packets transformers, eg:

onrtctransform = transformer => {
  const decrypter = new SFrameDecryterStream({mode: `packet`);
  transformer.readable
    .pipeThrough(new TransformStream(myMetadataTransform))
    .pipeThrough(decrypter)
    .pipeTo(writable);
};

Should it disallow creating a combination of transformers of different kind?