GUIDE TO INSTALLATION AND OPERATION
44
| IRD-3811
•
MPEG1 Layer II
•
MPEG2 Audio
•
AAC audio (2 CH or AAC-LC)
The first audio can be embedded as 5.1 discrete channels (the Dolby option is required to get discreet channels;
otherwise you get 2 down-mixed channels) while the second audio is always output as 2 channels. Downmix mode
can be selected between Lt/Rt or Lo/Ro modes independently for both audios.
The primary and secondary audio can be set in pass-through mode for AC3 data streams. This allows embedding
raw AC3 streams into the SDI signal.
Audio only services can be decoded
Audio PIDs not belonging to the current service cannot be selected
Only supported audio streams will be available to the user for selection
Audio 1 is embedded on AES channels 1 to 6, Audio 2 is on channels 7-8 by default. The user may
set up a different configuration.
The Dolby option must be activated to get 6 discrete AC3 channels on the SDI
Simultaneous decoding of AAC-LC and AC3 audios is not possible.
4.3 MPEG AV Synchronization
MPEG transport streams normally contain information about the encoder clock system in order to genlock the decoder
to the incoming signal and avoid buffer underrun or overflows. Moreover, the audio and video streams contain time
stamps (PTS) in order to re-synchronize the stream at the output.
Should synchronization be a problem (PCR jitter, bad PTS), the MPEG clock recover system can be manually forced
to OFF. In such case, the system decoder clock is free run and frames are repeated or dropped to cope with buffer
overflows or underflows (frame buffer mode).
Setting the clock recovery in the OFF mode is particularly useful when network jitter is important and the video sync or
audio sync status of the IRD keeps blinking.
To change the clock recovery mode, go to the card menu into
Input Menu
,
CLOCK RECOVERY
Refer to section 3.4.6 for iControl.
4.4 About V-CHIP & Rating Information
The video stream may already contain XDS advisory data. If XDS data is already present, it is left untouched. No V-
CHIP is generated if no XDS data is present.
Closed captioning data must be present in the MPEG video stream or XDS data will not be inserted at
the output
