Add enabling variable for extended precision audio

Set AudioFlinger::kEnableExtendedPrecision = true to enable
extended precision. Enabling will be required for devices (such as
USB) which report 24 bit or 32 bit sink formats.

Change-Id: I0dc1d7a4f7607086d7b536ea0e43aef0e696f2ee

3 files changed, 43 insertions, 10 deletions

diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index 527fd65..11a01cc 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -1621,6 +1621,19 @@ audio_io_handle_t AudioFlinger::openOutput(audio_module_handle_t module,
     mHardwareStatus = AUDIO_HW_OUTPUT_OPEN;
 
     audio_stream_out_t *outStream = NULL;
+
+    // FOR TESTING ONLY:
+    // Enable increased sink precision for mixing mode if kEnableExtendedPrecision is true.
+    if (kEnableExtendedPrecision &&  // Check only for Normal Mixing mode
+            !(flags & (AUDIO_OUTPUT_FLAG_COMPRESS_OFFLOAD | AUDIO_OUTPUT_FLAG_DIRECT))) {
+        // Update format
+        //config.format = AUDIO_FORMAT_PCM_FLOAT;
+        //config.format = AUDIO_FORMAT_PCM_24_BIT_PACKED;
+        //config.format = AUDIO_FORMAT_PCM_32_BIT;
+        //config.format = AUDIO_FORMAT_PCM_8_24_BIT;
+        // ALOGV("openOutput() upgrading format to %#08x", config.format);
+    }
+
     status_t status = hwDevHal->open_output_stream(hwDevHal,
                                           id,
                                           *pDevices,
@@ -1644,9 +1657,9 @@ audio_io_handle_t AudioFlinger::openOutput(audio_module_handle_t module,
         if (flags & AUDIO_OUTPUT_FLAG_COMPRESS_OFFLOAD) {
             thread = new OffloadThread(this, output, id, *pDevices);
             ALOGV("openOutput() created offload output: ID %d thread %p", id, thread);
-        } else if ((flags & AUDIO_OUTPUT_FLAG_DIRECT) ||
-            (config.format != AUDIO_FORMAT_PCM_16_BIT) ||
-            (config.channel_mask != AUDIO_CHANNEL_OUT_STEREO)) {
+        } else if ((flags & AUDIO_OUTPUT_FLAG_DIRECT)
+                || !isValidPcmSinkFormat(config.format)
+                || (config.channel_mask != AUDIO_CHANNEL_OUT_STEREO)) {
             thread = new DirectOutputThread(this, output, id, *pDevices);
             ALOGV("openOutput() created direct output: ID %d thread %p", id, thread);
         } else {
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 6e73a14..ddc6afb 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -326,6 +326,24 @@ private:
                                                 audio_devices_t devices);
     void                    purgeStaleEffects_l();
 
+    // Set kEnableExtendedPrecision to true to use extended precision in MixerThread
+    static const bool kEnableExtendedPrecision = false;
+
+    // Returns true if format is permitted for the PCM sink in the MixerThread
+    static inline bool isValidPcmSinkFormat(audio_format_t format) {
+        switch (format) {
+        case AUDIO_FORMAT_PCM_16_BIT:
+            return true;
+        case AUDIO_FORMAT_PCM_FLOAT:
+        case AUDIO_FORMAT_PCM_24_BIT_PACKED:
+        case AUDIO_FORMAT_PCM_32_BIT:
+        case AUDIO_FORMAT_PCM_8_24_BIT:
+            return kEnableExtendedPrecision;
+        default:
+            return false;
+        }
+    }
+
     // standby delay for MIXER and DUPLICATING playback threads is read from property
     // ro.audio.flinger_standbytime_ms or defaults to kDefaultStandbyTimeInNsecs
     static nsecs_t          mStandbyTimeInNsecs;
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index d6390b1..792d722 100755
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -1157,12 +1157,12 @@ AudioFlinger::PlaybackThread::PlaybackThread(const sp<AudioFlinger>& audioFlinge
                                              type_t type)
     :   ThreadBase(audioFlinger, id, device, AUDIO_DEVICE_NONE, type),
         mNormalFrameCount(0), mSinkBuffer(NULL),
-        mMixerBufferEnabled(false),
+        mMixerBufferEnabled(AudioFlinger::kEnableExtendedPrecision),
         mMixerBuffer(NULL),
         mMixerBufferSize(0),
         mMixerBufferFormat(AUDIO_FORMAT_INVALID),
         mMixerBufferValid(false),
-        mEffectBufferEnabled(false),
+        mEffectBufferEnabled(AudioFlinger::kEnableExtendedPrecision),
         mEffectBuffer(NULL),
         mEffectBufferSize(0),
         mEffectBufferFormat(AUDIO_FORMAT_INVALID),
@@ -1401,9 +1401,10 @@ sp<AudioFlinger::PlaybackThread::Track> AudioFlinger::PlaybackThread::createTrac
                 frameCount, mFrameCount);
       } else {
         ALOGV("AUDIO_OUTPUT_FLAG_FAST denied: isTimed=%d sharedBuffer=%p frameCount=%d "
-                "mFrameCount=%d format=%d isLinear=%d channelMask=%#x sampleRate=%u mSampleRate=%u "
+                "mFrameCount=%d format=%#x mFormat=%#x isLinear=%d channelMask=%#x "
+                "sampleRate=%u mSampleRate=%u "
                 "hasFastMixer=%d tid=%d fastTrackAvailMask=%#x",
-                isTimed, sharedBuffer.get(), frameCount, mFrameCount, format,
+                isTimed, sharedBuffer.get(), frameCount, mFrameCount, format, mFormat,
                 audio_is_linear_pcm(format),
                 channelMask, sampleRate, mSampleRate, hasFastMixer(), tid, mFastTrackAvailMask);
         *flags &= ~IAudioFlinger::TRACK_FAST;
@@ -1809,9 +1810,10 @@ void AudioFlinger::PlaybackThread::readOutputParameters_l()
     if (!audio_is_valid_format(mFormat)) {
         LOG_ALWAYS_FATAL("HAL format %#x not valid for output", mFormat);
     }
-    if ((mType == MIXER || mType == DUPLICATING) && mFormat != AUDIO_FORMAT_PCM_16_BIT) {
-        LOG_ALWAYS_FATAL("HAL format %#x not supported for mixed output; "
-                "must be AUDIO_FORMAT_PCM_16_BIT", mFormat);
+    if ((mType == MIXER || mType == DUPLICATING)
+            && !isValidPcmSinkFormat(mFormat)) {
+        LOG_FATAL("HAL format %#x not supported for mixed output",
+                mFormat);
     }
     mFrameSize = audio_stream_frame_size(&mOutput->stream->common);
     mBufferSize = mOutput->stream->common.get_buffer_size(&mOutput->stream->common);