It uses the same audio coding parameters as NICAM-3. This variant was known as NICAM-728, after the 728 kbit/s bitstream it is sent over. NICAM's second role – transmission to the public – was developed in the 80s by the BBC. Īudio is encoded using 14 bit pulse-code modulation at a sampling rate of 32 kHz. NICAM-3, which had been proposed during the test to address this, was selected as the winner. It was found that NICAM-2 provided the best sound quality, but reduced programme-modulated noise to an unnecessarily low level at the expense of bit rate. A NICAM-type system proposed by Télédiffusion de France (14:9).A RAI system which used A-law companding to compress 14-bit linear PCM samples into 10 bits (14:10).Several similar systems had been developed in various countries, and in about 1977/78 the BBC Research Department conducted listening tests to evaluate them. This figure was chosen to match the E1 primary multiplex rate, and systems using this rate could make use of the planned PDH national and international telecommunications networks. NICAM was originally intended to provide broadcasters with six high-quality audio channels within a total bandwidth of 2048 kbit/s. The application of this to broadcasting, in which the companding was to be done entirely digitally after the ADC and before the DAC, was described in a 1972 BBC Research Report. In this, the 'ranging' was to be applied to the analogue signal before the analogue-to-digital converter (ADC) and after the digital-to-analogue converter (DAC). In the 1980s, broadcasters began to use NICAM compression for transmissions of stereo TV sound to the public. It was originally developed in the early 1970s for point-to-point links within broadcasting networks. Near Instantaneous Companded Audio Multiplex ( NICAM) is an early form of lossy compression for digital audio. For the media content rating institute, see Netherlands Institute for the Classification of Audiovisual Media. This article is about a compression form for digital audio.
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