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know the negotiated codec (aac or sbc)

Thomas Rauturau
Intellectual 440 points


Hello,

I used the Bluetopia Platform Manager.

With the good SS1BTPM, I can use my gst-launch pipeline with aac (iphone) and another gst-lauch with sbc (old android).

In the HCI log (by DEVM_EnableBluetoothDebug function), I can saw the right capability (SBC or AAC)

In my application, I need to know the negotiated codec to start the good gst-launch.

I used the AUDM_Query_Audio_Stream_Configuration () function at different times, but the MediaCodecType parameter is always at the same value.

Have you ever had this problem ?

 

Sincerely

Thomas

  • 0
    TI__Genius 13052 points

    Hi Thomas,

    Does AUDM_Query_Audio_Stream_Configuration return SBC every time for the MediaCodecType parameter? What value are you receiving for the MediaCodecType?

    Thanks,
    Jacob

  • 0 in reply to Jacob B.
    Intellectual 440 points

    Hi Jacob,

    I called the AUDM_Query_Audio_Stream_Configuration function in the audio AUDM_Event_Callback (case aetAudioStreamConnected).
    I checked parameters (good device addresse, astSNK) and I checked the return parameter.

    The MediaCodecType is always at 0.

    Though I stream with my aac gst-lauch pipeline.

    Thanks,

    Thomas.

  • 0 in reply to Thomas Rauturau
    TI__Genius 13052 points

    Hi Thomas,

    I'll try to provide more insight here on tomorrow or early next week.

    Thank you for your patience,

    Jacob

  • 0 in reply to Jacob B.
    TI__Genius 13052 points

    Hi Thomas,

    If you are receiving 0x00 for the MediaCodecType, this means your application is defaulting to use the SBC codec. In the A2DPAPI.h file, you can find the media codec type constants:

    These constants are created based on the Bluetooth assigned numbers for A2DP:

    It seems like your program needs to specify the AAC codec for iPhone. Does your gst-launch currently work with Android?

    Can you try setting the AAC codec by using the AUD_Change_Stream_Format function? In this API, you can specify AAC with "AUD_STREAM_FORMAT_FLAGS_CODEC_TYPE_AAC."

    Best regards,
    Jacob

  • 0 in reply to Jacob B.
    Intellectual 440 points

    Hi,,

    Thanks for your answer Jacob. but my problem is not in this direction.

    I don't need to force the codec type. It's automatic between the stack and the smartphone
    It works very well.
    If I connect an Iphone, I start a gst-launch with the aac codec and it works
    If I connect an Android (old android with only sbc), I start a gst-launch with the sbc codec and it works.


    My goal : start automatically a gst-launch with the right codec.

    So I need to know which codec was decided between the stack and the phone.

    I looked in the HCI logs and I can clearly see this negotiation.
    But I will not parse the HCI logs to know the negotiated codec.

    The AUDM_Query_Audio_Stream_Configuration function should give me this information, right?

    Sincerely, Thomas.

  • 0 in reply to Thomas Rauturau
    TI__Genius 13052 points

    Hi Thomas,

    I believe that is the correct function. I'll check to see if there is another function for your use case tomorrow.

    Thanks,
    Jacob

  • 0 in reply to Jacob B.
    TI__Genius 13052 points

    Hi Thomas,

    Looking into this some more, I could not find a better API to use. I will have to reproduce this issue on my end.

    Thanks,

    Jacob

  • 0 in reply to Jacob B.
    TI__Genius 13052 points

    Hi Thomas,

    Can you show me how you call gst-launch with the return value from AUDM_Query_Audio_Stream_Configuration()? I'm wondering if there is a way for you to identify that you are using iPhone versus Android before calling gst-launch. It seems that BluetopiaPM is defaulting to SBC regardless of which phone you use.

    Also, are you using an external codec? I do not think our controllers support AAC if you are sending audio over I2S.

    Thanks,
    Jacob