Add floating point volume handling to AudioMixer

Use floating point volume in AudioMixer mixing when floating
point input is used with the new mixer engine.
AudioResampler is updated to take floating point volume to match.
Both legacy integer and floating point mixer engines work.

For now, integer volume is used when the new mixer engine
runs in integer input mode, for backward compatibility with
the legacy mixer.  The new mixer engine will generally run in
floating point input mode. When the legacy path is removed,
the integer volumes will be removed.

Change-Id: I79e80c292ae7c8b8bdd0aa371a1b2c3a1b618290

1 files changed, 10 insertions, 9 deletions

diff --git a/services/audioflinger/AudioResamplerDyn.cpp b/services/audioflinger/AudioResamplerDyn.cpp
index 043c803..e201ff8 100644
--- a/services/audioflinger/AudioResamplerDyn.cpp
+++ b/services/audioflinger/AudioResamplerDyn.cpp
@@ -27,6 +27,7 @@
 #include <cutils/properties.h>
 #include <utils/Debug.h>
 #include <utils/Log.h>
+#include <audio_utils/primitives.h>
 
 #include "AudioResamplerFirOps.h" // USE_NEON and USE_INLINE_ASSEMBLY defined here
 #include "AudioResamplerFirProcess.h"
@@ -190,17 +191,17 @@ void AudioResamplerDyn<TC, TI, TO>::init()
 }
 
 template<typename TC, typename TI, typename TO>
-void AudioResamplerDyn<TC, TI, TO>::setVolume(int16_t left, int16_t right)
+void AudioResamplerDyn<TC, TI, TO>::setVolume(float left, float right)
 {
     AudioResampler::setVolume(left, right);
-    // volume is applied on the output type.
     if (is_same<TO, float>::value || is_same<TO, double>::value) {
-        const TO scale = 1. / (1UL << 12);
-        mVolumeSimd[0] = static_cast<TO>(left) * scale;
-        mVolumeSimd[1] = static_cast<TO>(right) * scale;
-    } else {
-        mVolumeSimd[0] = static_cast<int32_t>(left) << 16;
-        mVolumeSimd[1] = static_cast<int32_t>(right) << 16;
+        mVolumeSimd[0] = static_cast<TO>(left);
+        mVolumeSimd[1] = static_cast<TO>(right);
+    } else {  // integer requires scaling to U4_28 (rounding down)
+        // integer volumes are clamped to 0 to UNITY_GAIN so there
+        // are no issues with signed overflow.
+        mVolumeSimd[0] = u4_28_from_float(clampFloatVol(left));
+        mVolumeSimd[1] = u4_28_from_float(clampFloatVol(right));
     }
 }
 
@@ -410,7 +411,7 @@ void AudioResamplerDyn<TC, TI, TO>::setSampleRate(int32_t inSampleRate)
     // Note: A stride of 2 is achieved with non-SIMD processing.
     int stride = ((c.mHalfNumCoefs & 7) == 0) ? 16 : 2;
     LOG_ALWAYS_FATAL_IF(stride < 16, "Resampler stride must be 16 or more");
-    LOG_ALWAYS_FATAL_IF(mChannelCount > 8 || mChannelCount < 1,
+    LOG_ALWAYS_FATAL_IF(mChannelCount < 1 || mChannelCount > 8,
             "Resampler channels(%d) must be between 1 to 8", mChannelCount);
     // stride 16 (falls back to stride 2 for machines that do not support NEON)
     if (locked) {