From 4e2293f29f2e719af1245d365747ea06d074b345 Mon Sep 17 00:00:00 2001
From: Glenn Kasten <gkasten@google.com>
Date: Thu, 12 Apr 2012 09:39:07 -0700
Subject: AudioMixer new cmd: remove sample rate converter

Add a new command REMOVE to remove any sample rate converter
   on a track, without having to delete the track name.
Add comments.
Remove some dead code.
Fix whitespace and comparison to NULL.

Change-Id: Id55a23ab5ee673189e99675b4e6fa5df7b617987
---
 services/audioflinger/AudioMixer.cpp | 20 ++++++++++----------
 services/audioflinger/AudioMixer.h   | 16 ++++++++++++++--
 2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/services/audioflinger/AudioMixer.cpp b/services/audioflinger/AudioMixer.cpp
index 05fa3b9..100f289 100644
--- a/services/audioflinger/AudioMixer.cpp
+++ b/services/audioflinger/AudioMixer.cpp
@@ -327,15 +327,9 @@ void AudioMixer::deleteTrackName(int name)
         track.enabled = false;
         invalidateState(1<<name);
     }
-    if (track.resampler != NULL) {
-        // delete the resampler
-        delete track.resampler;
-        track.resampler = NULL;
-        track.sampleRate = mSampleRate;
-        invalidateState(1<<name);
-    }
-    track.volumeInc[0] = 0;
-    track.volumeInc[1] = 0;
+    // delete the resampler
+    delete track.resampler;
+    track.resampler = NULL;
     mTrackNames &= ~(1<<name);
 }
 
@@ -439,6 +433,12 @@ void AudioMixer::setParameter(int name, int target, int param, void *value)
             track.resetResampler();
             invalidateState(1 << name);
             break;
+        case REMOVE:
+            delete track.resampler;
+            track.resampler = NULL;
+            track.sampleRate = mSampleRate;
+            invalidateState(1 << name);
+            break;
         default:
             LOG_FATAL("bad param");
         }
@@ -499,7 +499,7 @@ void AudioMixer::setParameter(int name, int target, int param, void *value)
 
 bool AudioMixer::track_t::setResampler(uint32_t value, uint32_t devSampleRate)
 {
-    if (value!=devSampleRate || resampler) {
+    if (value != devSampleRate || resampler != NULL) {
         if (sampleRate != value) {
             sampleRate = value;
             if (resampler == NULL) {
diff --git a/services/audioflinger/AudioMixer.h b/services/audioflinger/AudioMixer.h
index a04fe95..9698d0c 100644
--- a/services/audioflinger/AudioMixer.h
+++ b/services/audioflinger/AudioMixer.h
@@ -70,8 +70,17 @@ public:
         AUX_BUFFER      = 0x4003,
         DOWNMIX_TYPE    = 0X4004,
         // for target RESAMPLE
-        SAMPLE_RATE     = 0x4100,
-        RESET           = 0x4101,
+        SAMPLE_RATE     = 0x4100, // Configure sample rate conversion on this track name;
+                                  // parameter 'value' is the new sample rate in Hz.
+                                  // Only creates a sample rate converter the first time that
+                                  // the track sample rate is different from the mix sample rate.
+                                  // If the new sample rate is the same as the mix sample rate,
+                                  // and a sample rate converter already exists,
+                                  // then the sample rate converter remains present but is a no-op.
+        RESET           = 0x4101, // Reset sample rate converter without changing sample rate.
+                                  // This clears out the resampler's input buffer.
+        REMOVE          = 0x4102, // Remove the sample rate converter on this track name;
+                                  // the track is restored to the mix sample rate.
         // for target RAMP_VOLUME and VOLUME (8 channels max)
         VOLUME0         = 0x4200,
         VOLUME1         = 0x4201,
@@ -237,7 +246,10 @@ private:
     // indicates whether a downmix effect has been found and is usable by this mixer
     static bool                isMultichannelCapable;
 
+    // Call after changing either the enabled status of a track, or parameters of an enabled track.
+    // OK to call more often than that, but unnecessary.
     void invalidateState(uint32_t mask);
+
     static status_t prepareTrackForDownmix(track_t* pTrack, int trackNum);
 
     static void track__genericResample(track_t* t, int32_t* out, size_t numFrames, int32_t* temp, int32_t* aux);
-- 
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