Can HDMI's audio be adjusted?

conteczxy — Thu, 29 Dec 2016 00:45:17 GMT

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.

Re: Can HDMI's audio be adjusted?

weidong_sun — Thu, 29 Dec 2016 02:25:43 GMT

Hi Xiyuan,

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

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

Two modifications were needed to adjust hdmi volume:

“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;

}

// 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;

}

From

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

mFixedVolumeDevices &= ~AudioSystem.DEVICE_OUT_AUX_DIGITAL;

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

Best Regards

Weidong

conteczxy — Thu, 29 Dec 2016 03:42:25 GMT

Thank you very much for your fast and effective response。