ITU-R BR 1422-1999 Operational Practices for Television Use of Film Soundtracks Encoded with Noise Reduction and Matrix Surround《对于具有噪声减少和矩阵环绕声影片声轨迹编码的电视使用的操作实践》.pdf

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.