How to give blank data for Oboe library to play as sound?

Question

Sometimes I want my audio output in Oboe to play nothing, but I dont want it to stop, I just want it to be silent while no data arrives. I tried:

static void writeBlankData(float* pointer, int numFrames) {
    std::fill_n(pointer, numFrames, 0);
}
oboe::DataCallbackResult PlayRecordingCallback::onAudioReady(
        oboe::AudioStream *audioStream,
        void *audioData,
        int numFrames) {
    float *floatData = (float *) audioData;
    writeBlankData(floatData, numFrames);
    return oboe::DataCallbackResult::Continue;
}

but I hear a buzzing on the audio output instead of silence. Shouldn't an array of 0s be silence? I tried -1.0f also which gives a different buzzing.

score 3 · Accepted Answer · answered Aug 25 '20 at 16:43

3

The most likely cause is that the stream is in stereo so has 2 samples per frame. Your current code assumes a mono stream.

Try changing:

writeBlankData(floatData, numFrames);

To:

writeBlankData(floatData, numFrames * audioStream->getChannelCount());

answered Aug 25 '20 at 16:43

donturner

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Hello Don, does writing blank data cause any overheads? Like battery consumption etc In my app i only want to play the audio when user touches a button, to get the minimal latency should I keep the stream open and only write non blank data when user presses the button? – cs guy Nov 04 '20 at 14:49
1

There will be some extra power consumption associated with keeping a stream open. I don't have any figures on how much extra power is used but I don't imagine it to be significant when compared to keeping the screen on. – donturner Nov 10 '20 at 14:41

How to give blank data for Oboe library to play as sound?

1 Answers1