Function macBluetoothNativeInputRate

src/core/AudioEngine.cpp:448–495

}

std::optional<int> macBluetoothNativeInputRate(const QAudioDevice& qtDevice)
{
    const auto deviceId = macAudioDeviceForUid(qtDevice.id());
    if (!deviceId) {
        return std::nullopt;
    }

    const auto transport = readMacAudioScalar<UInt32>(*deviceId, kAudioDevicePropertyTransportType);
    if (!transport
        || (*transport != kAudioDeviceTransportTypeBluetooth
            && *transport != kAudioDeviceTransportTypeBluetoothLE)) {
        return std::nullopt;
    }

    bool hasHighRate = false;
    int exactLowRate = 0;
    const QList<AudioValueRange> nominalRanges = readMacAudioArray<AudioValueRange>(
        *deviceId,
        kAudioDevicePropertyAvailableNominalSampleRates);
    for (const AudioValueRange& range : nominalRanges) {
        if ((range.mMinimum <= 44100.0 && range.mMaximum >= 44100.0)
            || (range.mMinimum <= 48000.0 && range.mMaximum >= 48000.0)) {
            hasHighRate = true;
        }

        const int minRate = static_cast<int>(std::lround(range.mMinimum));
        const int maxRate = static_cast<int>(std::lround(range.mMaximum));
        if (minRate == maxRate && isMacBluetoothLowRate(minRate)) {
            exactLowRate = std::max(exactLowRate, minRate);
        }
    }

    if (hasHighRate) {
        return std::nullopt;
    }

    const auto nominalRate = readMacAudioScalar<Float64>(*deviceId, kAudioDevicePropertyNominalSampleRate);
    const int roundedNominal = nominalRate ? static_cast<int>(std::lround(*nominalRate)) : 0;
    if (isMacBluetoothLowRate(roundedNominal)) {
        return roundedNominal;
    }

    if (exactLowRate > 0) {
        return exactLowRate;
    }

    return std::nullopt;
}
// (macTxInputRateCandidates removed — TX mic rate negotiation now goes through
//  the consolidated AudioFormatNegotiator ladder; #2930's preferred-rate-first
//  and #2615's Bluetooth-HFP native rate are encoded there, fed by