Enabling accurate demodulation of a dvd bit stream using devices including a sync window generator controlled by a read channel bit counter

Abstract

A method of processing a DVD bitstream includes the steps of reading the DVD bitstream, the bitstream including a sync frame. A sync window is created, the sync window being open at least during the expected timing of a sync detection signal within the sync frame. The sync pattern is detected within the sync frame and the sync detection signal is generated only when the sync pattern has been detected and the sync window is open. A DVD sync pattern detection circuit includes a sync window generator to generate a sync window signal, a sync pattern detector, the sync pattern detector generating a sync detection signal only when both a sync pattern is detected in a DVD input stream and the sync window signal is asserted. A read channel bit counter generates a read counter signal to control the sync window generator, the read channel bit counter being reset when the sync pattern detector detects the sync pattern. The read channel bit counter controls the width of the sync window signals to allow the generation of correctly timed demodulation enable signals even when the sync frames have non-standard bit lengths. The sync windows also prevent the erroneous detection of sync patterns within the data portions of the sync frames. A pseudo sync detection signal is generated when the sync pattern is corrupted or missing from the sync frame.