A processing system can include an encoder to encode a real-time transmission of a presentation. A memory buffer can copy and store images of the presentation and convert the images into snapshot images. A transmitter can transmit the snapshot images to an external annotation device, and a receiver can receive annotation data of an annotation performed on the snapshot images at the external annotation device. The annotation can be encoded, in accordance with the annotation data, into the real-time transmission of the presentation to display the real-time transmission with the annotation.