Operating instructions

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Audio Output

Transcoding

The audio transcoder supports transcoding at 48 kHz only.

The audio output is formed of fully compliant MPEG-2 transport packets encapsulated into a

transport stream packet. The module runs in aligned mode where there are an integer

number of audio frames fitted into a PES packet, therefore a PES packet will be the start of

an audio packet.

The audio output rate is derived from the 27MHz reference clock.

Lip Sync

The Video Transcoder ensures that lip sync is maintained between the limits of audio leading

video by 10 ms to video leading audio by 30 ms.

PID Assignment

The module enables a PID to be assigned to each audio channel separately, which includes

the ability to assign separate PID’s to every mono channel. The PID value is configurable.

PCR Placeholders

The module enables a PCR placeholder to be put in the adaptation field of every audio PID

stream. See Appendices > Clock and Timing > Program Clock Reference (PCR)