private static async Task <Tuple <List <Frame>, BitrateType, TimeSpan, UInt32> > CollectSamplesAsync(IBinaryStream stream, UInt32 streamLength, UInt32?amount)
{
var samples = new List <Frame>();
var bitrateType = BitrateType.Constant;
var duration = new TimeSpan();
var bitrateSum = 0U;
var originalPosition = stream.Position;
while (stream.Position + 20 < streamLength)
{
if (amount.HasValue && (samples.Count == amount.Value))
{
break;
}
var possibleFrameHeader = await stream.PeekUInt32Async(ByteOrder.BigEndian).ConfigureAwait(false);
if ((possibleFrameHeader & 0xFFFE0000) == 0xFFFA0000)
{
var bitrate = Frame.GetBitrate(possibleFrameHeader);
var frequency = Frame.GetFrequency(possibleFrameHeader);
var padding = Frame.GetPadding(possibleFrameHeader);
var version = Frame.GetVersion(possibleFrameHeader);
var layer = Frame.GetLayer(possibleFrameHeader);
if ((bitrate != 0) && (frequency != 0))
{
var frame = new Frame(stream.Position, version, layer, bitrate, frequency, padding);
if (samples.Count == 0)
{
var firstFrameContent = await stream.ReadAsync(frame.Length).ConfigureAwait(false);
bitrateType = firstFrameContent.IndexOf("Xing").HasValue ? BitrateType.Variable : BitrateType.Constant;
}
else
{
stream.Position += frame.Length;
duration += frame.Duration;
bitrateSum += frame.Bitrate;
}
samples.Add(frame);
continue;
}
}
// this situation means that we've read some samples and haven't found valid sample right after the last valid sample
// and it means that the file in wrong format, corrupted or we've found all samples.
if (samples.Count > 0)
{
break;
}
stream.Position += 1;
if (stream.Position - originalPosition > 1024)
{
break;
}
}
return(new Tuple <List <Frame>, BitrateType, TimeSpan, UInt32>(samples, bitrateType, duration, (samples.Count > 0) ? (UInt32)(bitrateSum / samples.Count) : 0));
}
public static async Task <UInt32> ReadUInt32Async(this IBinaryStream stream, ByteOrder byteOrder)
{
var buffer = await stream.ReadAsync(4).ConfigureAwait(false);
var value = 0U;
for (var i = 0; i < 4; i++)
{
value |= (UInt32)buffer[i] << 8 * ((byteOrder == ByteOrder.BigEndian) ? (3 - i) : i);
}
return(value);
}
public static async Task <XingFrame> CreateAsync(IBinaryStream stream, Frame frame)
{
var position = stream.Position;
stream.Position = frame.Offset;
var data = await stream.ReadAsync(40).ConfigureAwait(false);
var index = data.IndexOf("Xing");
stream.Position = frame.Offset + index.Value + 4;
var framesCount = (UInt32?)null;
var bytesCount = (UInt32?)null;
var toc = (Byte[])null;
var quality = (UInt32?)null;
var flags = await stream.ReadUInt32Async(ByteOrder.BigEndian).ConfigureAwait(false);
if ((flags & 0x01) > 0)
{
framesCount = await stream.ReadUInt32Async(ByteOrder.BigEndian).ConfigureAwait(false);
}
if ((flags & 0x02) > 0)
{
bytesCount = await stream.ReadUInt32Async(ByteOrder.BigEndian).ConfigureAwait(false);
}
if ((flags & 0x04) > 0)
{
toc = await stream.ReadAsync(100).ConfigureAwait(false);
}
if ((flags & 0x08) > 0)
{
quality = await stream.ReadUInt32Async(ByteOrder.BigEndian).ConfigureAwait(false);
}
stream.Position = position;
return(new XingFrame()
{
FramesCount = framesCount, BytesCount = bytesCount, Quality = quality
});
}
public static async Task <Int32> ReadInt32Async(this IBinaryStream stream, Byte amount, ByteOrder byteOrder)
{
if (amount > 4)
{
throw new ArgumentOutOfRangeException();
}
var buffer = await stream.ReadAsync(amount).ConfigureAwait(false);
var value = 0;
for (var i = 0; i < amount; i++)
{
value |= buffer[i] << 8 * ((byteOrder == ByteOrder.BigEndian) ? (amount - i - 1) : i);
}
return(value);
}
public static async Task <Byte> ReadByteAsync(this IBinaryStream stream)
{
var buffer = await stream.ReadAsync(1).ConfigureAwait(false);
return(buffer[0]);
}
public static async Task <String> ReadStringAsync(this IBinaryStream stream, UInt32 length)
{
var buffer = await stream.ReadAsync(length).ConfigureAwait(false);
return(Encoding.UTF8.GetString(buffer, 0, (Int32)length));
}
public static async Task <UInt16> ReadUInt16Async(this IBinaryStream stream, ByteOrder byteOrder)
{
var buffer = await stream.ReadAsync(2).ConfigureAwait(false);
return((UInt16)((byteOrder == ByteOrder.BigEndian) ? ((buffer[0] << 8) | buffer[1]) : (buffer[0] | (buffer[1] << 8))));
}
public static Task <Byte[]> GetDataAsync(IBinaryStream stream, DataLocation dataLocation)
{
stream.Position = dataLocation.Position;
return(stream.ReadAsync(dataLocation.Length));
}
public static async Task <Id3v2> ParseAsync(IBinaryStream stream)
{
stream.Position += 3;
var id3v2 = new Id3v2();
var majorVersion = await stream.ReadByteAsync().ConfigureAwait(false);
var revision = await stream.ReadByteAsync().ConfigureAwait(false);
var flags = await stream.ReadByteAsync().ConfigureAwait(false);
var size = Id3v2.DecodeSize(await stream.ReadUInt32Async(ByteOrder.BigEndian).ConfigureAwait(false));
var endingPosition = stream.Position + size;
while (stream.Position < endingPosition)
{
var frameId = await stream.ReadStringAsync(4).ConfigureAwait(false);
if (!Id3v2.IsValidAlphaNumeric(frameId))
{
stream.Position = endingPosition;
break;
}
var frameSize = 0U;
switch (majorVersion)
{
case 4:
frameSize = Id3v2.DecodeSize(await stream.ReadUInt32Async(ByteOrder.BigEndian).ConfigureAwait(false));
break;
case 3:
frameSize = await stream.ReadUInt32Async(ByteOrder.BigEndian).ConfigureAwait(false);
break;
default:
throw new NotSupportedException();
}
var frameFlags = await stream.ReadUInt16Async(ByteOrder.LittleEndian).ConfigureAwait(false);
switch (frameId)
{
case "TIT2":
id3v2.Title = Id3v2.DecodeString(await stream.ReadAsync(frameSize).ConfigureAwait(false));
break;
case "TALB":
id3v2.Album = Id3v2.DecodeString(await stream.ReadAsync(frameSize).ConfigureAwait(false));
break;
case "TOAL":
break;
case "TPE1":
id3v2.Artist = Id3v2.DecodeString(await stream.ReadAsync(frameSize).ConfigureAwait(false));
break;
case "TPE2":
id3v2.AlbumArtist = Id3v2.DecodeString(await stream.ReadAsync(frameSize).ConfigureAwait(false));
break;
case "TRCK":
var track = Id3v2.DecodeString(await stream.ReadAsync(frameSize).ConfigureAwait(false));
if (track != null)
{
id3v2.Track = ParseTrack(track);
}
break;
case "TYER":
var year = Id3v2.DecodeString(await stream.ReadAsync(frameSize).ConfigureAwait(false));
if (year != null)
{
id3v2.Year = ParseYear(year);
}
break;
case "APIC":
var readBytes = 0U;
var encoding = (FrameEncoding)await stream.ReadByteAsync().ConfigureAwait(false);
readBytes++;
while (await stream.ReadByteAsync().ConfigureAwait(false) != 0) // MIME type <text string> $00
{
readBytes++;
}
readBytes++;
var pictureType = await stream.ReadByteAsync().ConfigureAwait(false);
readBytes++;
while (await stream.ReadByteAsync().ConfigureAwait(false) != 0) // <text string according to encoding> $00 (00)
{
readBytes++;
}
id3v2.Cover = new DataLocation(stream.Position, frameSize - readBytes - 1);
stream.Position += frameSize - readBytes - 1;
break;
case "TCON":
case "COMM":
default:
stream.Position += frameSize;
break;
}
}
return(id3v2);
}
