Integrate improved coefficient sinc resampler: VHQ

Summary:
Very high quality is enabled only for 44.1 -> 48 or 48 -> 44.1,
  and uses low quality for all other use cases.
Track estimated CPU load and throttles the quality based on load;
  as currently configured it should allow up to 2 instances of very high quality.
Medium quality and high quality are currently disabled unless explicitly requested.

Details:
Only load .so the first time it is needed.
Cleanup code style: formatting, indentation, whitespace.
Restore medium quality resampler, but it is not used (see next line).
Fix memory leak for sinc resampler.
Check sample rate in resampler constructor.
Add logs for debugging.
Rename DEFAULT to DEFAULT_QUALITY for consistency with other quality levels.
Renumber VERY_HIGH_QUALITY from 255 to 4.
Use enum src_quality consistently.
Improve parsing of property af.resampler.quality.
Fix reentrancy bug - allow an instance of high quality and an instance
  of very high quality to both be active concurrently.

Bug: 7229644
Change-Id: I0ce6b913b05038889f50462a38830b61a602a9f7

1 files changed, 118 insertions, 16 deletions

diff --git a/services/audioflinger/AudioResampler.cpp b/services/audioflinger/AudioResampler.cpp
index 5c1c905..96293e3 100644
--- a/services/audioflinger/AudioResampler.cpp
+++ b/services/audioflinger/AudioResampler.cpp
@@ -24,9 +24,7 @@
 #include <cutils/properties.h>
 #include "AudioResampler.h"
 #include "AudioResamplerSinc.h"
-#if 0
 #include "AudioResamplerCubic.h"
-#endif
 
 #ifdef __arm__
 #include <machine/cpu-features.h>
@@ -42,7 +40,7 @@ namespace android {
 class AudioResamplerOrder1 : public AudioResampler {
 public:
     AudioResamplerOrder1(int bitDepth, int inChannelCount, int32_t sampleRate) :
-        AudioResampler(bitDepth, inChannelCount, sampleRate), mX0L(0), mX0R(0) {
+        AudioResampler(bitDepth, inChannelCount, sampleRate, LOW_QUALITY), mX0L(0), mX0R(0) {
     }
     virtual void resample(int32_t* out, size_t outFrameCount,
             AudioBufferProvider* provider);
@@ -79,29 +77,120 @@ private:
     int mX0R;
 };
 
+bool AudioResampler::qualityIsSupported(src_quality quality)
+{
+    switch (quality) {
+    case DEFAULT_QUALITY:
+    case LOW_QUALITY:
+#if 0   // these have not been qualified recently so are not supported unless explicitly requested
+    case MED_QUALITY:
+    case HIGH_QUALITY:
+#endif
+    case VERY_HIGH_QUALITY:
+        return true;
+    default:
+        return false;
+    }
+}
+
 // ----------------------------------------------------------------------------
-AudioResampler* AudioResampler::create(int bitDepth, int inChannelCount,
-        int32_t sampleRate, int quality) {
 
-    // can only create low quality resample now
-    AudioResampler* resampler;
+static pthread_once_t once_control = PTHREAD_ONCE_INIT;
+static AudioResampler::src_quality defaultQuality = AudioResampler::DEFAULT_QUALITY;
 
+void AudioResampler::init_routine()
+{
     char value[PROPERTY_VALUE_MAX];
-    if (property_get("af.resampler.quality", value, 0)) {
-        quality = atoi(value);
-        ALOGD("forcing AudioResampler quality to %d", quality);
+    if (property_get("af.resampler.quality", value, NULL) > 0) {
+        char *endptr;
+        unsigned long l = strtoul(value, &endptr, 0);
+        if (*endptr == '\0') {
+            defaultQuality = (src_quality) l;
+            ALOGD("forcing AudioResampler quality to %d", defaultQuality);
+            if (defaultQuality < DEFAULT_QUALITY || defaultQuality > VERY_HIGH_QUALITY) {
+                defaultQuality = DEFAULT_QUALITY;
+            }
+        }
     }
+}
 
-    if (quality == DEFAULT)
-        quality = LOW_QUALITY;
+uint32_t AudioResampler::qualityMHz(src_quality quality)
+{
+    switch (quality) {
+    default:
+    case DEFAULT_QUALITY:
+    case LOW_QUALITY:
+        return 3;
+    case MED_QUALITY:
+        return 6;
+    case HIGH_QUALITY:
+        return 20;
+    case VERY_HIGH_QUALITY:
+        return 34;
+    }
+}
+
+static const uint32_t maxMHz = 75;  // an arbitrary number that permits 2 VHQ, should be tunable
+static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+static uint32_t currentMHz = 0;
+
+AudioResampler* AudioResampler::create(int bitDepth, int inChannelCount,
+        int32_t sampleRate, src_quality quality) {
+
+    bool atFinalQuality;
+    if (quality == DEFAULT_QUALITY) {
+        // read the resampler default quality property the first time it is needed
+        int ok = pthread_once(&once_control, init_routine);
+        if (ok != 0) {
+            ALOGE("%s pthread_once failed: %d", __func__, ok);
+        }
+        quality = defaultQuality;
+        atFinalQuality = false;
+    } else {
+        atFinalQuality = true;
+    }
+
+    // naive implementation of CPU load throttling doesn't account for whether resampler is active
+    pthread_mutex_lock(&mutex);
+    for (;;) {
+        uint32_t deltaMHz = qualityMHz(quality);
+        uint32_t newMHz = currentMHz + deltaMHz;
+        if ((qualityIsSupported(quality) && newMHz <= maxMHz) || atFinalQuality) {
+            ALOGV("resampler load %u -> %u MHz due to delta +%u MHz from quality %d",
+                    currentMHz, newMHz, deltaMHz, quality);
+            currentMHz = newMHz;
+            break;
+        }
+        // not enough CPU available for proposed quality level, so try next lowest level
+        switch (quality) {
+        default:
+        case DEFAULT_QUALITY:
+        case LOW_QUALITY:
+            atFinalQuality = true;
+            break;
+        case MED_QUALITY:
+            quality = LOW_QUALITY;
+            break;
+        case HIGH_QUALITY:
+            quality = MED_QUALITY;
+            break;
+        case VERY_HIGH_QUALITY:
+            quality = HIGH_QUALITY;
+            break;
+        }
+    }
+    pthread_mutex_unlock(&mutex);
+
+    AudioResampler* resampler;
 
     switch (quality) {
     default:
+    case DEFAULT_QUALITY:
     case LOW_QUALITY:
         ALOGV("Create linear Resampler");
         resampler = new AudioResamplerOrder1(bitDepth, inChannelCount, sampleRate);
         break;
-#if 0
+#if 0   // disabled because it has not been qualified recently, if requested will use default:
     case MED_QUALITY:
         ALOGV("Create cubic Resampler");
         resampler = new AudioResamplerCubic(bitDepth, inChannelCount, sampleRate);
@@ -110,8 +199,9 @@ AudioResampler* AudioResampler::create(int bitDepth, int inChannelCount,
     case HIGH_QUALITY:
         ALOGV("Create HIGH_QUALITY sinc Resampler");
         resampler = new AudioResamplerSinc(bitDepth, inChannelCount, sampleRate);
+        break;
     case VERY_HIGH_QUALITY:
-        ALOGV("Create VERY_HIGH_QUALITY sinc Resampler = %d",quality);
+        ALOGV("Create VERY_HIGH_QUALITY sinc Resampler = %d", quality);
         resampler = new AudioResamplerSinc(bitDepth, inChannelCount, sampleRate, quality);
         break;
     }
@@ -122,17 +212,20 @@ AudioResampler* AudioResampler::create(int bitDepth, int inChannelCount,
 }
 
 AudioResampler::AudioResampler(int bitDepth, int inChannelCount,
-        int32_t sampleRate) :
+        int32_t sampleRate, src_quality quality) :
     mBitDepth(bitDepth), mChannelCount(inChannelCount),
             mSampleRate(sampleRate), mInSampleRate(sampleRate), mInputIndex(0),
             mPhaseFraction(0), mLocalTimeFreq(0),
-            mPTS(AudioBufferProvider::kInvalidPTS) {
+            mPTS(AudioBufferProvider::kInvalidPTS), mQuality(quality) {
     // sanity check on format
     if ((bitDepth != 16) ||(inChannelCount < 1) || (inChannelCount > 2)) {
         ALOGE("Unsupported sample format, %d bits, %d channels", bitDepth,
                 inChannelCount);
         // ALOG_ASSERT(0);
     }
+    if (sampleRate <= 0) {
+        ALOGE("Unsupported sample rate %d Hz", sampleRate);
+    }
 
     // initialize common members
     mVolume[0] = mVolume[1] = 0;
@@ -141,6 +234,15 @@ AudioResampler::AudioResampler(int bitDepth, int inChannelCount,
 }
 
 AudioResampler::~AudioResampler() {
+    pthread_mutex_lock(&mutex);
+    src_quality quality = getQuality();
+    uint32_t deltaMHz = qualityMHz(quality);
+    int32_t newMHz = currentMHz - deltaMHz;
+    ALOGV("resampler load %u -> %d MHz due to delta -%u MHz from quality %d",
+            currentMHz, newMHz, deltaMHz, quality);
+    LOG_ALWAYS_FATAL_IF(newMHz < 0, "negative resampler load %d MHz", newMHz);
+    currentMHz = newMHz;
+    pthread_mutex_unlock(&mutex);
 }
 
 void AudioResampler::setSampleRate(int32_t inSampleRate) {