Patent ID: 8503867

Claim:
A playback apparatus for playing back AV streams recorded on a recording medium in accordance with playlist information including a plurality of sets of playback section information, each set of playback section information specifying (i) a default AV stream and (ii) an IN_time and an OUT_time of each AV stream along a time axis thereof, the playback apparatus comprising: a playback section register for storing therein a playback section number of a current playback section; a playback unit operable to playback the default AV stream in the current playback section from the IN_time to the OUT_time thereof in the current playback section; an angle number register; and a transition control unit, wherein some of the sets of playback section information have a multi-stream extension structure, and some of the sets of playback section information do not have the multi-stream extension structure, the multi-stream extension structure specifying, from among the AV streams included in each set of playback section information, a second AV stream onward, when the current playback section has the multi-stream extension structure, the playback unit plays back, from among the default AV stream specified in the current playback section and the AV streams specified by the multi-stream extension structure of the current playback section, an AV stream that corresponds to an angle number stored in the angle number register, a sum of the number of the default AV stream specified in the current playback section and the number of the AV streams specified by the multi-stream extension structure of the current playback section indicates the number of valid angles in the current playback section, when the current playback section has changed to a next playback section indicated by a next set of playback section information in the playlist information and the post-change current playback section has the multi-stream extension structure, the transition control unit (i) judges whether or not the angle number stored in the angle number register is smaller than or equal to the number of valid angles in the post-change current playback section, and (ii) maintains the angle number if the judgment is affirmative, and writes a default angle number to the angle number register if the judgment is negative, and when a user has requested to change the angle number, the transition control unit (i) judges whether or not an angle number X, which is to be newly written to the angle number register, is smaller than or equal to the number of valid angles in the current playback section, and (ii) writes the angle number X to the angle number register if the judgment is affirmative, and maintains the angle number stored in the angle number register if the judgment is negative.