# Audio Device latencies & safety offsets on Mac

**URL:** <https://forum.juce.com/t/audio-device-latencies-safety-offsets-on-mac/15647>\
**Category:** MacOSX and iOS\
**Created:** [October 5, 2015, 7:35am UTC](https://forum.juce.com/t/audio-device-latencies-safety-offsets-on-mac/15647 "2015-10-05T07:35:34Z")\
**Posts on this page:** 1\
**Showing post:** 11

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**Author:** ![andrewj](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/andrewj/32/13428_2.png) [@andrewj](https://forum.juce.com/u/andrewj)\
**Post date:** [December 31, 2018, 3:44am UTC](https://forum.juce.com/t/audio-device-latencies-safety-offsets-on-mac/15647/11 "2018-12-31T03:44:34Z")

</div>

Good thought myhrman, but after a couple of hours of mucking around I’ve yet to see a non-zero stream latency.

The following code grafted into **juce\_mac\_CoreAudio.cpp** only checks the first stream, but I’ve tried looping through them all and checking that the AudioObjectGetPropertyData is successful. However I still only get zero unfortunately.

```
int getLatencyFromDevice (AudioObjectPropertyScope scope) const
{
    UInt32 deviceLatency = 0;
    UInt32 size = sizeof (deviceLatency);
    AudioObjectPropertyAddress pa;
    pa.mElement = kAudioObjectPropertyElementMaster;
    pa.mSelector = kAudioDevicePropertyLatency;
    pa.mScope = scope;
    AudioObjectGetPropertyData (deviceID, &pa, 0, nullptr, &size, &deviceLatency);

    UInt32 safetyOffset = 0;
    size = sizeof (safetyOffset);
    pa.mSelector = kAudioDevicePropertySafetyOffset;
    AudioObjectGetPropertyData (deviceID, &pa, 0, nullptr, &size, &safetyOffset);

    // Query stream latency
    UInt32 streamLatency = 0;
    UInt32 numStreams;
    pa.mSelector = kAudioDevicePropertyStreams;
    if (OK(AudioObjectGetPropertyDataSize (deviceID, &pa, 0, nullptr, &numStreams)))
    {
        HeapBlock<AudioStreamID> streams (numStreams);
        size = sizeof (AudioStreamID*);
        if (OK(AudioObjectGetPropertyData (deviceID, &pa, 0, nullptr, &size, streams)))
        {
            pa.mSelector = kAudioStreamPropertyLatency;
            size = sizeof (streamLatency);
            // We could check all streams for the device, but it only ever seems to return the stream latency on the first stream
            AudioObjectGetPropertyData (streams[0], &pa, 0, nullptr, &size, &streamLatency);
        }
    }
    
    std::cout << "deviceLatency: " << String(deviceLatency).toRawUTF8() << ", ";
    std::cout << "safetyOffset: " << String(safetyOffset).toRawUTF8() << ", ";
    std::cout << "streamLatency: " << String(streamLatency).toRawUTF8() << std::endl;

    return (int) (deviceLatency + safetyOffset + streamLatency);
}
```

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