The NorDig HD IRDs shall (see section 6.2.1) support reception of System A and/or System B, in addition to the audio requirements or SD IRDs.
• System A: E-AC3 [36] with ability to transcode to AC3 [36]
• System B: HE AAC [57] with ability to transcode to AC3 [36] or DTS [33]. The audio system(s) shall be implemented as specified in this chapter.
When the NorDig HD IRD is part of an integrated digital TV set (IDTV) that can not play out a complete multi-channel audio signal, it should have an S/PDIF output and/or an HDMI output, see sections 8.5 and 8.9.
If the IDTV has an analogue stereo audio output on an RCA connector, the audio shall be in sync with the video display.
Where audio leaves the IRD in an encoded form, the IRD shall compensate for the decoding latency of the selected form, as specified in section 6.1.2.1.
The NorDig HD STB shall have an HDMI output and should have an S/PDIF output, see sections 8.5 and 8.9.
When the NorDig HD IRD has analogue output(s), it shall be capable of decoding and down- mixing the following formats for the analogue outputs:
• HE AAC, if HE AAC is implemented in the IRD • AC3, if AC3 is implemented in the IRD
• E-AC3, if E-AC3 is implemented in the IRD • MPEG1 layer II (Musicam)
The NorDig HD IRD shall always have an audio signal present on the analogue outputs (SCART and stereo out, see section 8.5) whenever any of the supported four formats is received.
It shall be possible to control the audio level on the outputs primarily used for TV viewing (TV SCART and HDMI) with the remote control unit and buttons on the front panel (if present).
The NorDig HD IRD shall (1) have a user preference to control the audio level on outputs, primarily used for recording and home-cinema applications (VCR SCART, S/PDIF and HDMI), shall follow the volume control or stay at a fixed level.
Note 1: Not required for NorDig IRDs that are launched before July 2010
6.2.2.1 System A: Requirements on Audio handling
6.2.2.1.1 System A: Audio Output
NorDig HD IRDs supporting System A shall be capable of providing the following formats on the HDMI output connector:
• Pass-through of native bitstream (AC3 and E-AC3). • E-AC3 bitstream transcoded to AC3.
• PCM stereo from the decoded or down-mixed bitstream
The following formats should be provided for the HDMI output connector: • PCM multi-channel from the decoded bitstream.
• Pass-through of DTS bitstream.
The NorDig HD IRD shall be capable of providing the following formats on the S/PDIF connector:
• E-AC3 bitstream transcoded to AC3
• PCM stereo from the decoded or down-mixed bitstream • Pass-through of AC3 bitstream
Pass-through of DTS bitstream to the S/PDIF connector is optional.
6.2.2.1.2 System A: All pass-through, decoding and transcoding
NorDig HD IRD supporting System A shall
• decode AC3 streams at all bit rates and sample rates listed in ETSI TS 102 366 [36] (not including Annex E).
• (additionally) decode E-AC3 streams with data rates from 32 kbps to 3 024 kbps and support all sample rates listed in TS 102 366 [36] Annex E.
• be capable of transcoding E-AC3 bitstreams to AC3 bitstreams according to TS 102 366 [36]. Transcoding to AC3 audio streams shall be at a fixed bit rate of 640 kbps.
6.2.2.1.3 System A: Metadata
The IRD shall support the use of a complete set of Dolby metadata [36] embedded in the audio stream when decoding AC3 or E-AC3 bitstreams, transcoding E-AC3 bitstreams to AC3, or creating a PCM stereo downmix from a decoded E-AC3 or AC3 bitstream.
6.2.2.2 System B: Requirements on Audio Handling
6.2.2.2.1 System B: Audio Output
NorDig HD IRDs supporting System B shall be capable of providing the following formats on the HDMI output connector:
• Pass-through of native HE AAC bitstream (1).
• Multichannel HE AAC bitstream transcoded to AC3 or DTS. • PCM stereo from the decoded or down-mixed bitstream
The following formats should be provided for the HDMI output connector: • PCM multi-channel from the decoded bitstream.
• Pass-through of DTS bitstream.
The NorDig HD IRD shall be capable of providing the following formats on the S/PDIF connector:
• PCM stereo from the decoded or down-mixed bitstream • Multichannel HE AAC bitstream transcoded to AC3 or DTS Pass-through of DTS bitstream to the S/PDIF connector is optional.
6.2.2.2.2 System B: All pass-through, decoding and transcoding
NorDig HD IRDs supporting System B shall be capable of:
• decoding HE AAC Version 1 at Level 2 at sampling rates of 48 kHz according to ETSI TS 101 154 [29], Annex H.
• decoding, including downmixing HE AAC Version 1 at Level 4 (multi-channel, up to 5.1) at sampling rates of 48 kHz according to ETSI TS 101 154 [29], Annex H (downmix).
• transcoding HE AAC Version 1 at Level 4 (multi-channel, up to 5.1) at sampling rates of 48 kHz according to TS 101 154 [29], Annex H to AC3 or DTS.
If supported, transcoding to AC3 audio streams shall be according to TS 102 366 [36].
If supported, transcoding to DTS audio streams shall be according to TS 102 114 [33] at a fixed bit rate of 1,536 Mbps.
6.2.2.2.3 System B: Metadata
The NorDig HD IRD IRD shall support the use of the following aacPlus (HE AAC) metadata embedded in the audio stream when decoding HE AAC and transcoding HE AAC multichannel to AC3 or DTS:
• Dynamic Range Control according to ISO/IEC 14496-3 [57] • Program Reference Level according to ISO/IEC 14496-3 [57].
• Mix Down Parameters according to "Transmission of MPEG4 Ancillary Data" part of DVB specification ETSI TS 101 154 [29]