1、 Rec. ITU-R BR.1422 1 RECOMMENDATION ITU-R BR.1422 OPERATIONAL PRACTICES FOR TELEVISION USE OF FILM SOUNDTRACKS ENCODED WITH NOISE REDUCTION AND MATRIX SURROUND (Question ITU-R 218/10) (1999) Rec. ITU-R BR.1422 The ITU Radiocommunication Assembly, considering a) that a large and growing number of 35
2、 mm feature films are produced in multichannel sound; b) that a large number of the multichannel feature films are identified as Dolby Stereo or Dolby Stereo SR, and that films identified as Dolby Stereo utilize Dolby A-type noise reduction (companding), and films identified as Dolby Stereo SR use D
3、olby SR-type noise reduction; c) that Dolby Stereo and Dolby Stereo SR systems use the photographic analogue stereo tracks of 35 mm films; d) that films marked Dolby Stereo are compatible with expanders of the older Dolby A noise reduction systems; e) that films marked Dolby Stereo SR are compatible
4、 with the more recent Dolby SR noise reduction systems; f) that films using the Dolby Stereo SR yield lower noise in reproduction; g) that the stereo audio source can exist either in its original magnetic format or as a photographic analogue stereo track on 35 mm film; h) that a large number of broa
5、dcasters are transmitting or planning to transmit these feature films to television viewers; j) that a large number of home television viewers are equipped to reproduce Dolby multichannel sound in their homes; k) that a larger existing base of viewers are still equipped with mono and stereo reproduc
6、tion equipment, which will be receiving multichannel sound; l) that new multichannel sound transmission must be compatible with the existing mono and stereo equipment; m) that production of multichannel sound requires correct technological procedures before transmission; n) that Recommendation ITU-R
7、 BR.1287 gives some general guidance on the use of multichannel film soundtracks in broadcasting; o) that the European Broadcasting Union (EBU) Technical Recommendation R59-1999 gives some general guidance on the use of multichannel film soundtracks in broadcasting, recommends 1 that whenever possib
8、le, a stereo magnetic master or magnetic soundtrack should be used for sound reproduction. In the case where only the optical soundtrack copy is available, such a copy should be cleaned before transfer; 2 that as a principle, the reproduction of a stereo photographic soundtrack from a negative film
9、should be avoided because of higher distortion and noise level. Such a track should always be converted into a positive form; 3 that a stereo optical track should always be reproduced using a stereo optical pickup. If only a mono signal is required, it should be derived as a downmix from the two cha
10、nnel stereo signal after the two channels have been individually decoded with the appropriate noise reduction system; 2 Rec. ITU-R BR.1422 4 that the equipment for reproduction or expansion used corresponds to the type of noise reduction used to produce the film. If two versions of a film are availa
11、ble, it is advisable to always select the copy that yields the lowest noise; 5 that older noise reduction reproduction systems could play back films produced with lower noise yielding systems, the reverse should not be practised; 6 that since television reception does not allow as high a dynamic range as the cinema, if any correction of dynamic range is necessary, it should be done after noise reduction expansion and applied simultaneously on both encoded channels.
