examining audio file alternative to spotlight

Question

i'm looking for an efficient alternative to grabbing audio file attributes in case spotlight is turned off.

Spotlight's MDItem attributes: kMDItemDurationSeconds, kMDItemAudioEncodingApplication, kMDItemAudioBitRate, kMDItemAudioSampleRate,kMDItemAudioChannelCount, kMDItemCodecs, are possible.

however QTKit's movieAttributes (if the file can be a QTMovie type), are not as complete, only QTMovieDurationAttribute fills my spec.

should i use Audio Format Services : OSStatus AudioFormatGetProperty, or is there something else, perhaps more light-weight that will suffice in the absence of MDItem information ?

i don't need to modify or play any files, i only need to know the property values.

thanks.

Answer 1

Get attributes from the audio track's media, not the movie. Here is an example of how to get duration in seconds.

for (QTTrack* track in [movie tracks])
{
    QTMedia* trackMedia = [track media];

    if ([trackMedia hasCharacteristic:QTMediaCharacteristicAudio])
    {
        QTTime mediaDuration = [(NSValue*)[trackMedia attributeForKey:QTMediaDurationAttribute] QTTimeValue];
        long long mediaDurationScaleValue = mediaDuration.timeScale;
        long long mediaDurationTimeValue = mediaDuration.timeValue;
        result = (double)mediaDurationTimeValue / (double)mediaDurationScaleValue;
        break;
    }
}

[trackMedia mediaAttributes] will give you other available attributes of the audio.