| 摘要 |
<p>The major TV systems in the world use interlaced scanning and either 50Hz field frequency or 60Hz field frequency, denoted 50i and 60i, respectively. However, movies are produced in 24Hz frame frequency and progressive scanning, denoted 24p. In order to broadcast movies as TV programs, in 60Hz countries a 3:2 pull-down is applied in which every 3rd field is repeated, and in 50Hz countries a movie is replayed or broadcast about 4% faster. In 24p digital format the video signal is encoded using MPEG. Because 24p-related originally compressed audio data streams cannot be decoded and replayed 4% faster without carrying out a pitch conversion consuming a significant amount of processor time, DVD Video discs sold in 50Hz countries contain audio data streams that are already encoded such that the DVD player's decoder 'automatically' outputs a 4% faster audio signal. When introducing HDTV digitally compressed movies on discs the movie producers would like to provide movie content only in 24p format worldwide. According to the invention, a related disc player offers at least three different replay modi to the user:
- 24p format with original video and audio replay speed;
- 60i format with original audio replay speed and 3:2 pull-down for video;
- 50i format with original audio replay speed and 24:1 pull-down for video.</p> |
