Data access control method and apparatus

A data access control module comprises:

• a filter, configured to receive a plurality of data units consisting essentially of filtered data units and un-filtered data units and to filter the filtered data units;
• a timing record unit, configured to generate the timings of the data units outputted by the filter according to the received timings of the plurality of data units;
• a storage unit, configured to store the un-filtered data units;
• a timing recovery unit, configured to recover the timings of the un-filtered data units stored in the storage unit according to the timings recorded by the timing record unit;
• a replacement data unit insertion unit, configured to insert replacement data units to replace the filtered data units, wherein each of the replacement data units has the same timing as each of the filtered data units;
• and
• an output controller, configured to output the un-filtered data units and the replacement data unit according to the timings of the filtered data units and the timing of the replacement data unit, respectively.