ANSI SCTE 243-4-2018 pdf free download – Next Generation Audio Carriage for Cable Systems: Part 4 – DTS-UHD Audio Carriage Constraints.
Note that MaxPayloadCode can be used to determine the minimum IEC sample clock frequency required to transfer the DTS-UHD stream on a digital audio interface.
6.2.3.5 ExtendedDescriptor
ExtendedDescriptor is a 1-bit flag to be interpreted as a Boolean. If ExtendedDescriptor == 1, then additional private information bytes beyond this descriptor definition shall exist at the end of this definition. ExtendedPayloadBytes bytes shall be included in descriptor_length.
6.2.3.6 LongDescriptor
LongDescriptor is a 1-bit flag to be interpreted as a Boolean. For SCTE systems carrying NGA audio, when the audio_preselection_descriptor() is present, LongDescriptor shall be 0. For legacy channel based audio and when audio_preselection_descriptor() is not used, LongDescriptor may be set to 1. When LongDescriptor is set to 1 the LongDescriptor parameters shall be correctly populated as described in 6.2.4 below.
6.2.3.7Streamlndex
When a given Audio Program is delivered using multiple streams, StreamIndex is the index used toindicate stream priority for prioritizing mixing metadata. The main stream shall have StreamIndex=0,while auxiliary streams shall have StreamIndex values in the range of 1-7.
If the Audio Program is delivered in a single stream, StreamIndex shall be 0.
The value of StreamIndex shall correspond to the value of StreamID carried in the DTS-UHDBroadcastChunk as defined in SCTE DvS 242-4[3].
6.2.3.8reserved_bits
These bits serve to byte align some parameters in the descriptor and may be defined for use in futurespecifications. For the purposes of this specification, all reserved_bits shall be set to 0 and ignored by thereceiver.
6.2.3.9 ExtendedPayloadBytes
The number of bytes,ByteCount, is determined by parsing the parameters defined here and comparing thenumber of bytes remaining to be parsed based on descriptor_length. If ExtendedPayloadBytes exist,
receivers built to this this specification shall ignore this data.
6.2.4 LongDescriptor Parameters
The parameters described in this section are conditionally present if LongDescriptor [Table 1] is set to 1.6.2.4.1 NumPresentationsCode
This field represents the number of audio presentations encoded within DTS-UHD elementary stream.The valid range of the bitstream parameter m_ucNumAudioPres defined in TS 103 491 [7] is from l to32.The relationship between NumPresentationsCode and NumPresentations shall be as follows:
NunPvesentations = m_ucNamAudioPres = NumPresentationsCode + 1
6.2.4.2ChannelMask
A bit mask that indicates the channel layout encoded in the default presentation of the DTS-UHD
bitstream according to the bit-to-channel-label mapping described in Table 4.Note that the ChannelMasktable is derived from Channel Bitmask defined in TS 103 584 [8].
6.2.4.3 BaseSamplingFrequencyCode
BaseSamplingFrequencyCode is derived from the parameter m_unClockRateInHz defined in TS 103 491 [7]. This field shall indicate the base sampling frequency, according to Table 5.
Consistent with the constraints in ANSI/SCTE 242-1 [2], BaseSamplingFrequencyCode shall equal 1.
6.2.4.4 SampleRateMod
This field indicates the sampling frequency of the audio samples stored in the bitstream. It modifies the BaseSamplingFrequency by multiplying by the corresponding value indicated in Table 6.
Consistent with the constraints in ANSI/SCTE 242-1 [2], SampleRateMod shall equal 0.
6.2.4.5 RepresentationType
This value conveys general information about the type of spatial audio signals encoded in the default presentation of the DTS-UHD bit-stream according to the description in Table 7. This parameter shall match the bitstream metadata parameter ucObjRepresTypeIndex defined in TS 103 491 [7].
Allowed values for RepresentationType are affected by and may affect ChannelMask, as indicated.ANSI SCTE 243-4 pdf download.