public AudioInfo ReadAudioInfo(Stream stream)
{
Contract.Ensures(Contract.Result <AudioInfo>() != null);
var mp4 = new Mp4(stream);
uint dataSize = mp4.GetChildAtomInfo().Single(atom => atom.FourCC == "mdat").Size;
mp4.DescendToAtom("moov", "trak", "mdia", "minf", "stbl", "stts");
var stts = new SttsAtom(mp4.ReadAtom(mp4.CurrentAtom));
uint 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.SampleRate > 0)
{
return(new AudioInfo(string.Format(CultureInfo.CurrentCulture, "{0}kbps MPEG 4 AAC",
esds.AverageBitrate > 0
? (int)esds.AverageBitrate / 1000
: CalculateBitRate(dataSize, sampleCount, esds.SampleRate)), esds.Channels, 0,
(int)esds.SampleRate, sampleCount));
}
// Apple Lossless files have their own atom for storing audio info:
mp4.DescendToAtom("moov", "trak", "mdia", "minf", "stbl", "stsd", "alac");
var alac = new AlacAtom(mp4.ReadAtom(mp4.CurrentAtom));
return(new AudioInfo("Apple Lossless", alac.Channels, alac.BitsPerSample, (int)alac.SampleRate,
sampleCount));
}
internal AtomToMetadataAdapter(Mp4 mp4, AtomInfo[] atoms)
{
Contract.Requires(mp4 != null);
Contract.Requires(atoms != null);
foreach (AtomInfo atom in atoms)
{
byte[] atomData = mp4.ReadAtom(atom);
switch (atom.FourCC)
{
case "trkn":
var trackNumberAtom = new TrackNumberAtom(atomData);
Add("TrackNumber", trackNumberAtom.TrackNumber.ToString(CultureInfo.InvariantCulture));
if (trackNumberAtom.TrackCount > 0)
{
Add("TrackCount", trackNumberAtom.TrackCount.ToString(CultureInfo.InvariantCulture));
}
break;
case "©day":
// The ©day atom may contain a full date, or only the year:
var dayAtom = new TextAtom(atomData);
DateTime result;
if (DateTime.TryParse(dayAtom.Value, CultureInfo.CurrentCulture, DateTimeStyles.NoCurrentDateDefault, out result) && result.Year >= 1000)
{
base["Day"] = result.Day.ToString(CultureInfo.InvariantCulture);
base["Month"] = result.Month.ToString(CultureInfo.InvariantCulture);
base["Year"] = result.Year.ToString(CultureInfo.InvariantCulture);
}
else
{
base["Year"] = dayAtom.Value;
}
break;
case "covr":
try
{
CoverArt = new CoverArt(new CovrAtom(atomData).Value);
}
catch (UnsupportedCoverArtException)
{ }
break;
default:
string mappedKey;
if (_map.TryGetValue(atom.FourCC, out mappedKey))
{
base[mappedKey] = new TextAtom(atomData).Value;
}
break;
}
}
}
static byte[] GenerateIlst(Mp4 originalMp4, MetadataDictionary metadata, SettingsDictionary settings)
{
Contract.Requires(originalMp4 != null);
Contract.Requires(metadata != null);
Contract.Requires(settings != null);
Contract.Ensures(Contract.Result <byte[]>() != null);
using (var resultStream = new MemoryStream())
{
var adaptedMetadata = new MetadataToAtomAdapter(metadata, settings);
// "Reverse DNS" atoms may need to be preserved:
foreach (ReverseDnsAtom reverseDnsAtom in
from listAtom in originalMp4.GetChildAtomInfo()
where listAtom.FourCC == "----"
select new ReverseDnsAtom(originalMp4.ReadAtom(listAtom)))
{
switch (reverseDnsAtom.Name)
{
// Always preserve the iTunSMPB (gapless playback) atom:
case "iTunSMPB":
resultStream.Write(reverseDnsAtom.GetBytes(), 0, reverseDnsAtom.GetBytes().Length);
break;
// Preserve the existing iTunNORM atom if a new one isn't provided, and AddSoundCheck isn't explicitly False:
case "iTunNORM":
if (!adaptedMetadata.IncludesSoundCheck &&
string.Compare(settings["AddSoundCheck"], bool.FalseString,
StringComparison.OrdinalIgnoreCase) != 0)
{
resultStream.Write(reverseDnsAtom.GetBytes(), 0, reverseDnsAtom.GetBytes().Length);
}
break;
}
}
byte[] atomData = adaptedMetadata.GetBytes();
resultStream.Write(atomData, 0, atomData.Length);
return(resultStream.ToArray());
}
}
