Atsc working Draft Template
Table 6.25a List and Location of PSIP Descriptors Descriptor Name
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- Table 6.25b
Table 6.25a List and Location of PSIP Descriptors
Descriptor Name Descriptor Tag Terrestrial Broadcast PMT MGT TVCT EIT DCCT DCCSCT stuffing descriptor 0x80 * * * * * * AC-3 audio descriptor 0x81 M M caption service descriptor 0x86 O M content advisory descriptor 0x87 O M extended channel name descriptor 0xA0 M service location descriptor 0xA1 S time-shifted service descriptor 0xA2 M component name descriptor 0xA3 M DCC departing request descriptor 0xA8 M DCC arriving request descriptor 0xA9 M redistribution control descriptor 0xAA M M genre descriptor 0xAB M ATSC private information descriptor 0xAD * * * * * * E-AC-3_audio_stream_descriptor 0xCC M M Table 6.25b List and Location of PSIP Descriptors Descriptor Name Descriptor Tag Cable PMT MGT CVCT EIT DCCT DCCSCT stuffing descriptor 0x80 * * * * * * AC-3 audio descriptor 0x81 M M caption service descriptor 0x86 M M content advisory descriptor 0x87 M M extended channel name descriptor 0xA0 M service location descriptor 0xA1 M time-shifted service descriptor 0xA2 M component name descriptor 0xA3 M DCC departing request descriptor 0xA8 M DCC arriving request descriptor 0xA9 M redistribution control descriptor 0xAA M M 16 genre descriptor 0xAB M ATSC private information descriptor 0xAD * * * * * * E-AC-3_audio_stream_descriptor 0xCC M M The descriptors listed here are those currently defined. Others may be defined in the future. Receivers are expected to tolerate the presence of any descriptor within any descriptor loop in any table section. Additions to PSIP functionality are contemplated in the future and may result in additional descriptors being present in each of these tables. 6.9.1 Audio Descriptors in the EIT The descriptors in this section are used with audio elementary stream components. 16 When the EIT is present. 67 ATSC A/65:2013 Program and System Information Protocol 7 August 2013 6.9.1.1 AC-3 Audio Descriptors The AC-3_audio_stream_descriptor() (AC-3 audio descriptor), defined in Annex A of ATSC A/52 [1], as constrained in ATSC A/53 Part 3 [4] shall be used in the EIT when there is one or more audio service of stream_type 0x81 planned for or present as an element of the event. Note that this is an exception to the general practice of one descriptor per loop as when more than one audio is present the foregoing text requires more than one AC-3_audio_stream_descriptor() to be present. This enables, for example, announcement of audio language and stereo or 5.1 channels. If there is no audio service associated with the EIT event, the AC-3_audio_stream_descriptor() shall not be present for that event. When an event is scheduled with two or more audio elements with different languages, the language field shall be included in each AC-3_audio_stream_descriptor() . 6.9.1.2 E-AC-3 Audio Descriptors The E - AC-3_audio_stream_descriptor() (E-AC-3 audio descriptor), defined in Annex G of ATSC A/52 [1] shall be used in the EIT when there is an Elementary Stream component of stream_type 0x87 planned for or present as an element of the event. 6.9.1.3 Additional Considerations In order to assist the receiver in selection among multiple audio services, the optional fields in the AC-3_audio_stream_descriptor() and the E - AC-3_audio_stream_descriptor() should contain meaningful information. When both AC-3 and E-AC-3 are present for a given event, this information can further positively impact the quality of the user experience. 6.9.2 Caption Service Descriptor The caption service descriptor provides the signaling for the CAPTION CHANNEL SERVICE DIRECTORY as defined in CEA-708 [6], and announcement of CEA-608 data streams. The following metadata items referenced in the semantics of the fields of the Caption Service Descriptor shall be as defined in CEA-708 Section 4.5 [6]: LANGUAGE , TYPE OF SERVICE , SERVICE NUMBER , EASY READER , and DISPLAY ASPECT RATIO . This descriptor shall appear in the descriptor() field for each EIT event that has one or more closed captioning services during some portion of the event. When a caption_service_descriptor() is present in the TS_program_map_section() (as defined in ISO/IEC 13818-1 [13] section 2.4.4.8 and 2.4.4.9), it shall be placed in the descriptor loop for the video program element in the descriptor loop that immediately follows the ES_info_length field. This descriptor shall appear as a descriptor in the descriptor() field for each EIT event that has one or more closed captioning services during some portion of the event. If there is no captioning during the EIT event, the caption_service_descriptor() shall not be present for that event. The bit stream syntax for the closed captioning service descriptor shall be as shown in Table 6.26. 68 ATSC A/65:2013 Program and System Information Protocol 7 August 2013 Download 4.82 Kb. Do'stlaringiz bilan baham: |
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