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Commit 39fb5670 authored by Liejun Tao's avatar Liejun Tao Committed by Andre Eisenbach
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Bluetooth: Fine tune audio gain for Absolute Volume case 

Fine tune the audio gain for Bluetooth Absolute Volume.
Use 50%, 70% and 85% for lowest volume steps 1, 2 and 3.
Thus the volume change sounds smoother, more linear.
When remote end tune volume out of mute, we should also
tune the audio gain for the lowest volume steps.

Bug: 26694114
Change-Id: I298a334a4b40ddb87495fda1935349bfce8b0537
parent a0676c92

services/core/java/com/android/server/audio/AudioService.java

+32 −24
Original line number Diff line number Diff line
@@ -3940,33 +3940,40 @@ public class AudioService extends IAudioService.Stub { 
            }

        }



        // must be called while synchronized VolumeStreamState.class

        public void applyDeviceVolume_syncVSS(int device) {

            int index;

            if (mIsMuted) {

                index = 0;

            } else if ((device & AudioSystem.DEVICE_OUT_ALL_A2DP) != 0 && mAvrcpAbsVolSupported) {

        private int getAbsoluteVolumeIndex(int index) {

            /* Special handling for Bluetooth Absolute Volume scenario

             * If we send full audio gain, some accessories are too loud even at its lowest

             * volume. We are not able to enumerate all such accessories, so here is the

             * workaround from phone side.

                 * For the lowest volume steps 1 and 2, restrict audio gain to 50% and 75%.

             * Pre-scale volume at lowest volume steps 1 2 and 3.

             * For volume step 0, set audio gain to 0 as some accessories won't mute on their end.

             */

                int i = (getIndex(device) + 5)/10;

                if (i == 0) {

            if (index == 0) {

                // 0% for volume 0

                index = 0;

                } else if (i == 1) {

            } else if (index == 1) {

                // 50% for volume 1

                index = (int)(mIndexMax * 0.5) /10;

                } else if (i == 2) {

                    // 75% for volume 2

                    index = (int)(mIndexMax * 0.75) /10;

            } else if (index == 2) {

                // 70% for volume 2

                index = (int)(mIndexMax * 0.70) /10;

            } else if (index == 3) {

                // 85% for volume 3

                index = (int)(mIndexMax * 0.85) /10;

            } else {

                // otherwise, full gain

                index = (mIndexMax + 5)/10;

            }

            return index;

        }



        // must be called while synchronized VolumeStreamState.class

        public void applyDeviceVolume_syncVSS(int device) {

            int index;

            if (mIsMuted) {

                index = 0;

            } else if ((device & AudioSystem.DEVICE_OUT_ALL_A2DP) != 0 && mAvrcpAbsVolSupported) {

                index = getAbsoluteVolumeIndex((getIndex(device) + 5)/10);

            } else if ((device & mFullVolumeDevices) != 0) {

                index = (mIndexMax + 5)/10;

            } else {
@@ -3984,9 +3991,10 @@ public class AudioService extends IAudioService.Stub { 
                    if (device != AudioSystem.DEVICE_OUT_DEFAULT) {

                        if (mIsMuted) {

                            index = 0;

                        } else if (((device & AudioSystem.DEVICE_OUT_ALL_A2DP) != 0 &&

                                mAvrcpAbsVolSupported)

                                    || ((device & mFullVolumeDevices) != 0)) {

                        } else if ((device & AudioSystem.DEVICE_OUT_ALL_A2DP) != 0 &&

                                mAvrcpAbsVolSupported) {

                            index = getAbsoluteVolumeIndex((getIndex(device) + 5)/10);

                        } else if ((device & mFullVolumeDevices) != 0) {

                            index = (mIndexMax + 5)/10;

                        } else {

                            index = (mIndexMap.valueAt(i) + 5)/10;