diff options
Diffstat (limited to 'media/libstagefright/AudioSource.cpp')
-rw-r--r-- | media/libstagefright/AudioSource.cpp | 46 |
1 files changed, 46 insertions, 0 deletions
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 @@ AudioSource::AudioSource( 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 @@ static int skipFrame(int64_t timestampUs, } +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 @@ status_t AudioSource::read( 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); } |