Audio Data Stream - 3.1 English

HDMI 1.4/2.0 Receiver Subsystem Product Guide (PG236)

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3.1 English

An AXI4-Stream audio cycle is illustrated in the following figure. The data is valid when both the valid (TVLD) and ready (TRDY) signals are asserted. The HDMI 1.4/2.0 RX Subsystem sends out adjacent channels in sequential order (CH0, CH1, etc.). Usually, the audio stream receiver also expects the channels in sequential order. If the channel data is not in order, the channel data might be mapped into other channel sample slots. Audio signals are defined in Table 1.

Figure 1. Audio Cycle

In the HDMI 1.4/2.0 RX Subsystem, the number of Audio Channels is set through the software driver. You must enable the correct number of audio channels according to your use case and send the corresponding audio channel data mapping to the channel ID (TID). For example, if you intend to send out 8 channel audio, then you must set the Audio Channel number to 8 in the HDMI 1.4/2.0 RX Subsystem driver. Then, the corresponding audio data must be prepared and sent to the HDMI 1.4/2.0 RX Subsystem in the hardware, as described in the previous figure.

If an HDMI system does not require audio, tie all audio related input ports Low. The ports are:

  • s_axis_audio_aresetn
  • s_axis_audio_aclk
  • AUDIO_OUT_tready

Audio related output can be left unconnected. The ports are:

  • AUDIO_OUT (except tready)
  • acr_cts
  • acr_n
  • acr_valid

In the HDMI 1.4/2.0 RX Subsystem, L-PCM (IEC 60958, Packet Type 0x02), HBR (Packet Type 0x09), and 3D Audio ( Packet Type 0x0B) are handled by the hardware. For Aux packet with packet type = 0x02, the audio data are routed to the audio interface. Therefore, even IEC 61937 compressed audio is available at the audio interface. In this case, you must develop your module to retrieve and uncompress the audio.