GS2972 Datasheet, PDF (63/125 Pages) Semtech Corporation – 3G/HD/SD-SDI Serializer with Complete SMPTE Audio & Video Support

4.7.22 Audio Data Packet Insertion
In Normal Mode, the GS2972 embeds audio data packets into a space where all
pre-existing embedded audio data packets have been removed.
In Cascade Mode, the GS2972 embeds audio data packets contiguously after all of the
pre-existing audio data packets. The GS2972 does not replace any pre-existing audio
data packets with new audio packets, even if the new audio packets have the same
group number. In this situation, the new audio data packets are appended to the last
packet, and there is an illegal mix of different groups using the same group number. This
condition will be indicated by the following host interface bits:
Š MUX_ERRA: Set in Cascade Mode when Primary Group audio data packets are
added to video that already contains audio data packets with the same group
number
Š MUX_ERRB: Set in Cascade Mode when Secondary Group audio data packets
are added to video that already contains audio data packets with the same group
number
In Group Replacement Mode the GS2972 embeds audio data packets and sorts all of the
embedded audio data packets in order of group number. If there are any pre-existing
audio data packets with the same group number as the new audio packets, then the
pre-existing packets will be replaced.
In Group Replacement Mode the GS2972 replaces only the Primary Group audio if the
ONE_AGR host interface bit is set.
The GS2972 deletes arbitrary data packets if there is not enough room in the horizontal
ancillary data space to embed the selected audio data packets.
The GS2972 does not embed audio data packets when there is insufficient room in the
horizontal ancillary data space after deleting arbitrary data packets.
4.7.22.1 Audio Data Packet Insertion - SD only
The GS2972 embeds the audio channels specified by the ACT[8:1] host interface fields.
The GS2972 detects and preserves embedded EDH packets.
The GS2972 generates extended packets for 24-bit audio when the AUDIO_24BIT host
interface bit is set.
4.7.22.2 Blanking Values Following Audio Data Packet Insertion
For 3G Level A, Level B dual-stream, and Level B dual-link Y’C’_BC’_R 4:2:2 10-bit formats,
the audio insertion block will insert blanking data in accordance with the original video
format.
For all other video formats (for example: RGB 4:4:4 10-bit or 12-bit, Y’C’_BC’_R 12-bit), the
audio block will insert blanking values of 200h and 040h, which may not match the
blanking data of the original format.
GS2972 3G/HD/SD-SDI Serializer with Complete
SMPTE Audio & Video Support
Final Data Sheet Rev. 9
GENDOC-047479 September 2013
www.semtech.com
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