ToneGenerator: fix truncated tones

The first DTMF tone after a silent period is truncated.
This is because the phone app starts and stops the tone
when the user presses and releases the key.
This combined to the fact that the tones use the low latency path
and that when the output stream exists standby there is a period
of several milliseconds during which no audio is mixed until the
stream is "warmed up".
The result is that much less audio is generated than the actual
key press duration.

The fix consists in storing the tone start time and making sure that
the number of samples generated corresponds at least to the time difference
between the tone start and stop commands.

Bug 6607077

Change-Id: I070d20dd8600c25a9e5d5a60c1d3313b7917b00d

2 files changed, 32 insertions, 1 deletions

diff --git a/include/media/ToneGenerator.h b/include/media/ToneGenerator.h
index 0529bcd..2183fbe 100644
--- a/include/media/ToneGenerator.h
+++ b/include/media/ToneGenerator.h
@@ -271,6 +271,7 @@ private:
     float mVolume;  // Volume applied to audio track
     audio_stream_type_t mStreamType; // Audio stream used for output
     unsigned int mProcessSize;  // Size of audio blocks generated at a time by audioCallback() (in PCM frames).
+    struct timespec mStartTime; // tone start time: needed to guaranty actual tone duration
 
     bool initAudioTrack();
     static void audioCallback(int event, void* user, void *info);
diff --git a/media/libmedia/ToneGenerator.cpp b/media/libmedia/ToneGenerator.cpp
index 3554608..9ea3ea7 100644
--- a/media/libmedia/ToneGenerator.cpp
+++ b/media/libmedia/ToneGenerator.cpp
@@ -922,6 +922,9 @@ bool ToneGenerator::startTone(tone_type toneType, int durationMs) {
             ALOGV("Immediate start, time %d", (unsigned int)(systemTime()/1000000));
             lResult = true;
             mState = TONE_STARTING;
+            if (clock_gettime(CLOCK_MONOTONIC, &mStartTime) != 0) {
+                mStartTime.tv_sec = 0;
+            }
             mLock.unlock();
             mpAudioTrack->start();
             mLock.lock();
@@ -940,6 +943,7 @@ bool ToneGenerator::startTone(tone_type toneType, int durationMs) {
     } else {
         ALOGV("Delayed start");
         mState = TONE_RESTARTING;
+        mStartTime.tv_sec = 0;
         lStatus = mWaitCbkCond.waitRelative(mLock, seconds(3));
         if (lStatus == NO_ERROR) {
             if (mState != TONE_IDLE) {
@@ -978,7 +982,30 @@ void ToneGenerator::stopTone() {
     mLock.lock();
     if (mState != TONE_IDLE && mState != TONE_INIT) {
         if (mState == TONE_PLAYING || mState == TONE_STARTING || mState == TONE_RESTARTING) {
-            mState = TONE_STOPPING;
+            struct timespec stopTime;
+            // If the start time is valid, make sure that the number of audio samples produced
+            // corresponds at least to the time between the start and stop commands.
+            // This is needed in case of cold start of the output stream.
+            if ((mStartTime. tv_sec != 0) && (clock_gettime(CLOCK_MONOTONIC, &stopTime) == 0)) {
+                time_t sec = stopTime.tv_sec - mStartTime.tv_sec;
+                long nsec = stopTime.tv_nsec - mStartTime.tv_nsec;
+                long durationMs;
+                if (nsec < 0) {
+                    --sec;
+                    nsec += 1000000000;
+                }
+
+                if ((sec + 1) > ((long)(INT_MAX / mSamplingRate))) {
+                    mMaxSmp = sec * mSamplingRate;
+                } else {
+                    // mSamplingRate is always > 1000
+                    sec = sec * 1000 + nsec / 1000000; // duration in milliseconds
+                    mMaxSmp = (sec * mSamplingRate) / 1000;
+                }
+                ALOGV("stopTone() forcing mMaxSmp to %d, total for far %d", mMaxSmp,  mTotalSmp);
+            } else {
+                mState = TONE_STOPPING;
+            }
         }
         ALOGV("waiting cond");
         status_t lStatus = mWaitCbkCond.waitRelative(mLock, seconds(3));
@@ -1263,6 +1290,9 @@ audioCallback_EndLoop:
             ALOGV("Cbk restarting track");
             if (lpToneGen->prepareWave()) {
                 lpToneGen->mState = TONE_STARTING;
+                if (clock_gettime(CLOCK_MONOTONIC, &lpToneGen->mStartTime) != 0) {
+                    lpToneGen->mStartTime.tv_sec = 0;
+                }
                 // must reload lpToneDesc as prepareWave() may change mpToneDesc
                 lpToneDesc = lpToneGen->mpToneDesc;
             } else {