Can HDMI's audio be adjusted?

[conteczxy]

I am working on imx6q, android4.4.2, kernel 3.0.35, with hdmi display.

I found sound is output through hdmi, but when I adjust the sound to low or high in android settings-> sound volume, it doesn't take effect.

So, I want to know if it is possible to adjust sound of hdmi audio?

Thanks.

[weidong_sun]

Hi Xiyuan,

  I have got the following solution from my colleague and tested it!

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  Two modifications were needed to adjust hdmi volume:

1. “myandroid/hardware/libhardware_legacy/audio/AudioPolicyManagerBase.cpp”, function computeVolume()

From

    // if volume is not 0 (not muted), force media volume to max on digital output

    if (stream == AudioSystem::MUSIC &&

        index != mStreams[stream].mIndexMin &&

        (((device == AUDIO_DEVICE_OUT_AUX_DIGITAL) && (mDeviceIsHdmidongle == false)) ||

         device == AUDIO_DEVICE_OUT_DGTL_DOCK_HEADSET ||

         device == AUDIO_DEVICE_OUT_USB_ACCESSORY ||

         device == AUDIO_DEVICE_OUT_USB_DEVICE)) {

        return 1.0;

    }

To

    // if volume is not 0 (not muted), force media volume to max on digital output

    if (stream == AudioSystem::MUSIC &&

        index != mStreams[stream].mIndexMin &&

        (device == AUDIO_DEVICE_OUT_DGTL_DOCK_HEADSET ||

         device == AUDIO_DEVICE_OUT_USB_ACCESSORY ||

         device == AUDIO_DEVICE_OUT_USB_DEVICE)) {

        return 1.0;

    }

2. “myandroid/frameworks/base/media/java/android/media/AudioService.java

From

        if (SystemProperties.get("ro.product.device").contains("hdmidongle"))

                           mFixedVolumeDevices &= ~AudioSystem.DEVICE_OUT_AUX_DIGITAL;

To

       mFixedVolumeDevices &= ~AudioSystem.DEVICE_OUT_AUX_DIGITAL;

------------------------------------------------------------------------------------------------

Best Regards

Weidong

[conteczxy]

Thank you very much for your fast and effective response。