[ADV748x] How to detect / recognize / know the audio format information of received audio data.

Hi Tamu San,

         Apologies for the delayed response since i was on leave.

Please find the comment below,

  If there is another way to obtain the audio format information of received the audio, could you please tell me it?

    Yes, We can obtain the audio format information from the audio packet received from HDMI Rx.

   Please read the below information from audio packet registers according to the audio format and these register bit details may not be described in the UG-747 (Rev. 0) - Page 91

Also Please check the algorithm that can be implemented to monitor the type of audio packet processed by the HDMI Rx in Page 115(figure 44) at "ADV7625_HW_Manual_RevPrB_31May2013" at ez.analog.com/.../1663.ADV7625_5F00_Documentation.zip and this flow will be same for ADV748x part.

Kindly note that, As per ADV748x hardware manual, We can interpret the audio samples packet upto 192khz frequencies with 8 channel.

But Audio samples sampled at frequencies over 192khz are not supported by ADV748x and these only stated in Page 107 as "It is important to note that the ADV748x does not interpret the audio samples received"

Thanks,

Poornima

Hi Poornima san,

Thank you for your reply.

However, the method you showed is different from the information we want to know.
The audio format information we specifically want to know is as follows:

Can ADV7480 detect / recognize these audio format information?
If there is any way to get these audio format information of the received audio by ADV7480, could you please tell me it?

If it is not possible, please let us know. I will inform the customer and ask them to consider another method. (For example, having the subsequent SoC detect it, etc.)

Thank you!
Best regards.
Tamu

Hi Tamu San,

   Can ADV7480 detect / recognize this audio format information?

           Yes, By reading the audio infoframe register we can get the above listed audio formats. Please refer below snap.

           We can get the audio coding type by reading '0x1D[7:4]' register and we can get the channel count with bit position '0x1D[2:0]'. Kindly check and let us know.

Kindly note that, Audio InfoFrame registers are considered valid if the following two conditions are met:

  -- audio_info_raw is set to 1.
  -- aud_inf_cks_err_raw is set to 0. This condition applies only if always_store_inf is set to 1.

Please refer section "5.3.20.5 Audio InfoFrame Registers" in ADV748x hardware manual.

Thanks,

Poornima

Hi Poornima san,

Thank you for your reply.

As I stated in my first post in this thread, the CEA-861-D and HDMI specifications state:

CEA-861-D specification says as follows:

HDMI 1.4 specification says as follows:

The above "CT" bits indicate the audio format (audio coding type). These "CT" bits are Audio infoframe "0x1D[7:4]" you mentioned.
As shown above, the CEA-861-D and HDMI specifications state that the "CT" bits are all "0" in the case of HDMI.
So when we read the Audio Infoframe "0x1D[7:4]" from ADV7480, it just indicates all "0"s and it is not possible to detect (know) the audio format (audio coding type).

So I think that ADV748x can not detect (recognize, know) what kind of audio format (audio coding type) information of the received audio data is.
Is my understanding correct?
If there is any other way to get the audio format information of received the audio, could you please tell me it?

If it is not possible, please let us know. I will inform the customer and ask them to consider another method. (For example, having the subsequent SoC detect it, etc.)

Thank you!
Best regards.
Tamu

Hi Tamu San,

        Please find the below comment,

So I think that ADV748x can not detect (recognize, know) what kind of audio format (audio coding type) information of the received audio data is.
Is my understanding correct?

  Yes, ADV748x cannot detect the audio coding type information.

If there is any other way to get the audio format information of received the audio, could you please tell me it ?

   As stated, We can obtain the audio packet information like 'LPCM/DSD/HBR' from ADV748x and this we have been verified from our end.

If it is not possible, please let us know. I will inform the customer and ask them to consider another method. (For example, having the subsequent SoC detect it, etc.)

   Here also we tried to read audio coding type from audio info frame but it's not possible for us to read 'Audio coding type' from ADV748x.

Note: Audio InfoFrame, the IEC 60958-3 [12] “Channel Status” bits, and the IEC 61937-2 [93] “Burst Info” bits are used to describe the transmitted audio stream. The Audio InfoFrame CT (coding type), SS (sample size) and SF (sample frequency) fields are required to be 0 (“Refer to Stream Header”) to avoid redundancy with the same data already contained within the IEC 60958-3 [12] stream data.

Thanks,

Poornima