Audio Clock Regeneration Interface - 3.2 English

HDMI 1.4/2.0 Transmitter Subsystem Product Guide (PG235)

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3.2 English

The audio clock regeneration (ACR) interface has a Cycle Time Stamp (CTS) parameter vector and an Audio Clock Regeneration Value (N) parameter vector. Both vectors are 20 bits wide. The valid signal is driven High when the CTS and N parameters are stable. For more information, see Chapter 7 of the HDMI 1.4 specification.

On the rising edge of the valid signal, the TX reads the CTS and N parameters from the ACR input interface and transmits an audio clock regeneration packet.

The following table shows the Audio Clock Regeneration (ACR) interface signals. This interface runs at the s_axis_audio_aclk clock rate.

Table 1. Audio Clock Regeneration (ACR) Interface
Name I/O Width Description
acr_cts I 20 CTS
acr_n I 20 N
acr_valid I 1 Valid

If an HDMI system does not require audio, tie the following input ports Low:

  • AUDIO_IN (except tready)
  • s_axis_audio_aresetn
  • s_axis_audio_aclk
  • acr_cts
  • acr_n
  • acr_valid
Important: When multiple channel audio is enabled in the system, ensure that the audio data is properly sent to its respective channel allocation. Unused channels must be packed with zero (that is, Mute) to avoid audio channel swapping, which means audio data might appear in unexpected channel locations.