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Getting duration of an audio file
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Getting duration of an audio file

Here's the code I'm using to get the duration (in seconds) of an audio file:

SInt64 packetCount;
UInt32 dataSize = sizeof packetCount;
OSStatus result = AudioFileGetProperty(audioFile, kAudioFilePropertyAudioDataPacketCount, &dataSize, &packetCount);
if (result==noErr) {
double duration = ((double)packetCount * myASBD.mFramesPerPacket) / myASBD.mSampleRate;
}

Here, myASBD is the AudioStreamBasicDescription for audioFile. Is this code correct? If so, is it exact for variable-bit rate files, or is the calculated duration an estimate? It appears to be exact, but I'd rather be sure.

Thanks,
-Peter
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