Provided is an information recording medium which achieves high speed conversion of a signal input from external from MPEG-TS to MPEG-PS complying with DVD standard. An apparatus and a method for recording information to the information recording medium are also provided. A constrained format which enables conversion from a first stream (for example, MPEG transport stream) to a second stream (for example, MPEG program stream) is provided. The constrained format defines that a first packet (for example, TS packet) is grouped and managed in multiplexing unit. The first one (AF#8) of complete audio frames in the multiplexing unit (402) is the first one of audio frames in a payload of a second packet (for example, PES packet) (413).