code: function encodeEmbeddedFileBuffer( encoder, buffer_type, filename, mime_type ) {
  	// Get MIME And payload
  	var mime = mime_type || mimeTypeFromFilename( filename ),
  		mime_id = encoder.stringID( mime ),
  		buffer = bufferFromFile( filename );
  
  	// Write buffer header
  	encoder.log(LOG.EMB,"file='"+filename+"', mime="+mime+", len="+buffer.length);
  	encodeBuffer( encoder, buffer_type, mime_id, buffer );
  
  }
docs: Enbode a file as an embedded buffer