Suppress the video recording start signal
- bug 2950297
Change-Id: I0044d07178691feb904cf81e87c1b6d4b714dc1a
diff --git a/include/media/stagefright/AudioSource.h b/include/media/stagefright/AudioSource.h
index 2597e9e..1af4254 100644
--- a/include/media/stagefright/AudioSource.h
+++ b/include/media/stagefright/AudioSource.h
@@ -49,7 +49,17 @@
virtual ~AudioSource();
private:
- enum { kMaxBufferSize = 2048 };
+ enum {
+ kMaxBufferSize = 2048,
+
+ // After the initial mute, we raise the volume linearly
+ // over kAutoRampDurationUs.
+ kAutoRampDurationUs = 300000,
+
+ // This is the initial mute duration to suppress
+ // the video recording signal tone
+ kAutoRampStartUs = 700000,
+ };
AudioRecord *mRecord;
status_t mInitCheck;
@@ -67,6 +77,12 @@
void trackMaxAmplitude(int16_t *data, int nSamples);
+ // This is used to raise the volume from mute to the
+ // actual level linearly.
+ void rampVolume(
+ int32_t startFrame, int32_t rampDurationFrames,
+ uint8_t *data, size_t bytes);
+
AudioSource(const AudioSource &);
AudioSource &operator=(const AudioSource &);
};
diff --git a/media/libstagefright/AudioSource.cpp b/media/libstagefright/AudioSource.cpp
index c8dfede..4c729e4 100644
--- a/media/libstagefright/AudioSource.cpp
+++ b/media/libstagefright/AudioSource.cpp
@@ -40,6 +40,7 @@
mGroup(NULL) {
LOGV("sampleRate: %d, channels: %d", sampleRate, channels);
+ CHECK(channels == 1 || channels == 2);
uint32_t flags = AudioRecord::RECORD_AGC_ENABLE |
AudioRecord::RECORD_NS_ENABLE |
AudioRecord::RECORD_IIR_ENABLE;
@@ -158,6 +159,38 @@
}
+void AudioSource::rampVolume(
+ int32_t startFrame, int32_t rampDurationFrames,
+ uint8_t *data, size_t bytes) {
+
+ const int32_t kShift = 14;
+ int32_t fixedMultiplier = (startFrame << kShift) / rampDurationFrames;
+ const int32_t nChannels = mRecord->channelCount();
+ int32_t stopFrame = startFrame + bytes / sizeof(int16_t);
+ int16_t *frame = (int16_t *) data;
+ if (stopFrame > rampDurationFrames) {
+ stopFrame = rampDurationFrames;
+ }
+
+ while (startFrame < stopFrame) {
+ if (nChannels == 1) { // mono
+ frame[0] = (frame[0] * fixedMultiplier) >> kShift;
+ ++frame;
+ ++startFrame;
+ } else { // stereo
+ frame[0] = (frame[0] * fixedMultiplier) >> kShift;
+ frame[1] = (frame[1] * fixedMultiplier) >> kShift;
+ frame += 2;
+ startFrame += 2;
+ }
+
+ // Update the multiplier every 4 frames
+ if ((startFrame & 3) == 0) {
+ fixedMultiplier = (startFrame << kShift) / rampDurationFrames;
+ }
+ }
+}
+
status_t AudioSource::read(
MediaBuffer **out, const ReadOptions *options) {
*out = NULL;
@@ -242,6 +275,19 @@
continue;
}
+ if (mPrevSampleTimeUs - mStartTimeUs < kAutoRampStartUs) {
+ // Mute the initial video recording signal
+ memset((uint8_t *) buffer->data(), 0, n);
+ } else if (mPrevSampleTimeUs - mStartTimeUs < kAutoRampStartUs + kAutoRampDurationUs) {
+ int32_t autoRampDurationFrames =
+ (kAutoRampDurationUs * sampleRate + 500000LL) / 1000000LL;
+
+ int32_t autoRampStartFrames =
+ (kAutoRampStartUs * sampleRate + 500000LL) / 1000000LL;
+
+ int32_t nFrames = numFramesRecorded - autoRampStartFrames;
+ rampVolume(nFrames, autoRampDurationFrames, (uint8_t *) buffer->data(), n);
+ }
if (mTrackMaxAmplitude) {
trackMaxAmplitude((int16_t *) buffer->data(), n >> 1);
}
