GS3471 datasheet(80/179 Pages) SEMTECH

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GS3471

Final Data Sheet Rev.4

PDS-060498

September 2017

80 of 179

Semtech

www.semtech.com

The Audio Group Detect registers are set HIGH when audio data packets with a

corresponding group DID are detected in the input video stream. The host interface

reports the individual audio groups detected.

For SD, when an audio data packet with a DID set in IDA[1:0] and IDB[1:0] is detected,

the audio sample information is extracted and written into the audio FIFO. For HD and

3G, EXTEND_IDA and EXTEND_IDB are used in addition to IDA[1:0] and IDB[1:0] to

select one of 8 audio groups.

The embedded audio group selected by IDA[1:0] is described henceforth in this

document as Group A or Primary Group. The embedded audio group selected by

IDB[1:0] is described henceforth in this document as Group B or Secondary Group.

4.21.2.3 Audio Control Packets

The audio de-embedder automatically detects the presence of audio control packets in

the video stream. When audio control packets for audio Group A are detected, the

CTRA_DET bit of the host interface is set HIGH. When audio control packets for audio

Group B are detected, the CTRB_DET bit of the host interface is set HIGH.

The audio control packet data is accessible via the host interface.

The audio control packets must be embedded according to SMPTE ST 272 (SD) or SMPTE

ST 299 (HD and 3G). In 3G Level A signals, the audio control packets must be embedded

only in Data Stream 1. In 3G Level B signals the audio control packets must be

embedded in the Luma streams of each link that carries audio.

Note 1: In SD, HD, and 3G, the audio control packet reporting via the host interface

updates automatically when a new control packet is detected.

Note 2: If there is an HD audio packet checksum error, no audio is extracted. The audio

packet is not recognized, and the audio stays in the video stream. If nothing but the CLK

phase parity bit is wrong, the audio will extract fine.

Table 4-18: Audio Data Packet Detect Register

Name

Description

Default

ADPG8_DET

Audio Group Eight Data Packet Detection (1: Detected) (HD/3G only)

ADPG7_DET

Audio Group Seven Data Packet Detection (1: Detected) (HD/3G only)

ADPG6_DET

Audio Group Six Data Packet Detection (1: Detected) (HD/3G only)

ADPG5_DET

Audio Group Five Data Packet Detection (1: Detected) (HD/3G only)

ADPG4_DET

Audio Group Four Data Packet Detection (1: Detected)

ADPG3_DET

Audio Group Three Data Packet Detection (1: Detected)

ADPG2_DET

Audio Group Two Data Packet Detection (1: Detected)

ADPG1_DET

Audio Group One Data Packet Detection (1: Detected)

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