public AudioMetadata ReadMetadata(Stream stream)
{
var mp4 = new Mp4Model(stream);
if (mp4.DescendToAtom("moov", "udta", "meta", "ilst"))
{
return(new IlstAtomToMetadataAdapter(mp4, mp4.GetChildAtomInfo()));
}
throw new AudioUnsupportedException("No ilst atom found.");
}
public AudioInfo ReadAudioInfo(Stream stream)
{
try
{
var mp4 = new Mp4Model(stream);
mp4.DescendToAtom("moov", "trak", "mdia", "minf", "stbl", "stts");
var stts = new SttsAtom(mp4.ReadAtom(mp4.CurrentAtom));
var sampleCount = stts.PacketCount * stts.PacketSize;
mp4.DescendToAtom("moov", "trak", "mdia", "minf", "stbl", "stsd", "mp4a", "esds");
var esds = new EsdsAtom(mp4.ReadAtom(mp4.CurrentAtom));
if (esds.IsAac)
{
mp4.Reset();
return(AudioInfo.CreateForLossy("AAC", esds.Channels, (int)esds.SampleRate, sampleCount,
CalculateBitRate(mp4.GetChildAtomInfo().Single(atom =>
atom.FourCc.Equals("mdat", StringComparison.Ordinal)).Size,
sampleCount,
esds.SampleRate)));
}
// Apple Lossless files have their own atom for storing audio info
if (!mp4.DescendToAtom("moov", "trak", "mdia", "minf", "stbl", "stsd", "alac"))
{
throw new AudioUnsupportedException("Only AAC and ALAC MP4 streams are supported.");
}
var alac = new AlacAtom(mp4.ReadAtom(mp4.CurrentAtom));
return(AudioInfo.CreateForLossless(
"ALAC",
alac.Channels,
alac.BitsPerSample,
(int)alac.SampleRate,
sampleCount));
}
catch (EndOfStreamException e)
{
throw new AudioInvalidException(e.Message);
}
}
