Patent ID: 7965634

Claim:
A transmission rate adjustment device for adjusting a transmission rate of an input transport stream without using a hardware-implemented PLL (phase locked loop) circuit that controls the adjusted transmission rate, the transmission rate adjustment device taking as input a transport stream that comprises a plurality of transport packets having a fixed packet length in which encoded data are stored, and in which time stamps of a prescribed frequency that is a standard time interval during said encoding are inscribed at fixed time intervals, said transmission rate adjustment device comprising: a buffer; a buffer write unit that both successively writes transport packets of said input transport stream to said buffer and detects time stamps in said input transport stream; and a buffer read unit that takes as input both a frequency division rate signal that designates a frequency division rate and system clocks of a decoder for decoding said encoded data, and that transmits to said decoder transport packets that have been sequentially read from said buffer at a transmission rate determined by clocks obtained by frequency-dividing the input system clocks by the frequency division rate designated by the input frequency division rate signal, wherein: said buffer write unit, upon detecting said time stamps, stores in said buffer: a difference between a first time stamp that has been detected this time and a second time stamp that was previously detected, a number of transport packets that exist in an interval between the first and second time stamps, and a value of said second time stamp as appended information of the transport packet to which said second time stamp is inscribed; and said buffer read unit, upon reading from said buffer a transport packet to which said second time stamp has been inscribed, based on said appended information that has been attached to the transport packet, inserts NULL packets between transport packets that have been read from said buffer to achieve adjustment such that said transport packets are transmitted at said transmission rate, and when adjustment cannot be achieved by a mere insertion of NULL packets, when reading from said buffer the transport packet in which said first time stamp has been inscribed, rewrites the time stamp of the transport packet, said transmission rate adjustment device thereby providing a software-implemented mechanism based on said frequency division rate signal to control the adjusted transmission rate rather than a hardware-implemented PLL (phase locked loop) circuit.