Variable-length packets transmitted over a serial link do not have packet-start fields or unique symbols to mark the beginning of each packet. A content filter receives a communication, determines that the communication includes an image, and extracts the image. A beater stick is connected with the toe end of the pedal board by a linkage that drives the beater stick against a bass drum when the pedal is depressed. The second circuit may be configured to generate a third bias signal in response to the first and the second bias signals and a second resistance. A number of threads allocated to processing a sample type may be dynamically modified.