public MatroskaFile(string path)
{
_path = path;
_stream = new FastFileStream(path);
// read header
var headerElement = ReadElement();
if (headerElement != null && headerElement.Id == ElementId.Ebml)
{
// read segment
_stream.Seek(headerElement.DataSize, SeekOrigin.Current);
_segmentElement = ReadElement();
if (_segmentElement != null && _segmentElement.Id == ElementId.Segment)
{
_valid = true; // matroska file must start with ebml header and segment
}
}
}
private void ReadVideoElement(Element videoElement)
{
Element element;
while (_stream.Position < videoElement.EndPosition && (element = ReadElement()) != null)
{
switch (element.Id)
{
case ElementId.PixelWidth:
_pixelWidth = (int)ReadUInt((int)element.DataSize);
break;
case ElementId.PixelHeight:
_pixelHeight = (int)ReadUInt((int)element.DataSize);
break;
default:
_stream.Seek(element.DataSize, SeekOrigin.Current);
break;
}
}
}
private void ReadTracksElement(Element tracksElement)
{
_tracks = new List<MatroskaTrackInfo>();
Element element;
while (_stream.Position < tracksElement.EndPosition && (element = ReadElement()) != null)
{
if (element.Id == ElementId.TrackEntry)
{
ReadTrackEntryElement(element);
}
else
{
_stream.Seek(element.DataSize, SeekOrigin.Current);
}
}
}
private void ReadTrackEntryElement(Element trackEntryElement)
{
long defaultDuration = 0;
bool isVideo = false;
bool isAudio = false;
bool isSubtitle = false;
var trackNumber = 0;
string name = string.Empty;
string language = "eng"; // default value
string codecId = string.Empty;
string codecPrivate = string.Empty;
//var biCompression = string.Empty;
int contentCompressionAlgorithm = -1;
int contentEncodingType = -1;
Element element;
while (_stream.Position < trackEntryElement.EndPosition && (element = ReadElement()) != null)
{
switch (element.Id)
{
case ElementId.DefaultDuration:
defaultDuration = (int)ReadUInt((int)element.DataSize);
break;
case ElementId.Video:
ReadVideoElement(element);
isVideo = true;
break;
case ElementId.Audio:
isAudio = true;
break;
case ElementId.TrackNumber:
trackNumber = (int)ReadUInt((int)element.DataSize);
break;
case ElementId.Name:
name = ReadString((int)element.DataSize, Encoding.UTF8);
break;
case ElementId.Language:
language = ReadString((int)element.DataSize, Encoding.ASCII);
break;
case ElementId.CodecId:
codecId = ReadString((int)element.DataSize, Encoding.ASCII);
break;
case ElementId.TrackType:
switch (_stream.ReadByte())
{
case 1:
isVideo = true;
break;
case 2:
isAudio = true;
break;
case 17:
isSubtitle = true;
break;
}
break;
case ElementId.CodecPrivate:
codecPrivate = ReadString((int)element.DataSize, Encoding.UTF8);
//if (codecPrivate.Length > 20)
// biCompression = codecPrivate.Substring(16, 4);
break;
case ElementId.ContentEncodings:
contentCompressionAlgorithm = 0; // default value
contentEncodingType = 0; // default value
var contentEncodingElement = ReadElement();
if (contentEncodingElement != null && contentEncodingElement.Id == ElementId.ContentEncoding)
{
ReadContentEncodingElement(element, ref contentCompressionAlgorithm, ref contentEncodingType);
}
break;
}
_stream.Seek(element.EndPosition, SeekOrigin.Begin);
}
_tracks.Add(new MatroskaTrackInfo
{
TrackNumber = trackNumber,
IsVideo = isVideo,
IsAudio = isAudio,
IsSubtitle = isSubtitle,
Language = language,
CodecId = codecId,
CodecPrivate = codecPrivate,
Name = name,
ContentEncodingType = contentEncodingType,
ContentCompressionAlgorithm = contentCompressionAlgorithm
});
if (isVideo)
{
if (defaultDuration > 0)
{
_frameRate = 1.0 / (defaultDuration / 1000000000.0);
}
_videoCodecId = codecId;
}
}
private MatroskaSubtitle ReadSubtitleBlock(Element blockElement, long clusterTimeCode)
{
var trackNumber = (int)ReadVariableLengthUInt();
if (trackNumber != _subtitleRipTrackNumber)
{
_stream.Seek(blockElement.EndPosition, SeekOrigin.Begin);
return null;
}
var timeCode = ReadInt16();
// lacing
var flags = (byte)_stream.ReadByte();
int frames;
switch (flags & 6)
{
case 0: // 00000000 = No lacing
System.Diagnostics.Debug.Print("No lacing");
break;
case 2: // 00000010 = Xiph lacing
frames = _stream.ReadByte() + 1;
System.Diagnostics.Debug.Print("Xiph lacing ({0} frames)", frames);
break;
case 4: // 00000100 = Fixed-size lacing
frames = _stream.ReadByte() + 1;
for (var i = 0; i < frames; i++)
{
_stream.ReadByte(); // frames
}
System.Diagnostics.Debug.Print("Fixed-size lacing ({0} frames)", frames);
break;
case 6: // 00000110 = EMBL lacing
frames = _stream.ReadByte() + 1;
System.Diagnostics.Debug.Print("EBML lacing ({0} frames)", frames);
break;
}
// save subtitle data
var dataLength = (int)(blockElement.EndPosition - _stream.Position);
var data = new byte[dataLength];
_stream.Read(data, 0, dataLength);
return new MatroskaSubtitle(data, clusterTimeCode + timeCode);
}
private void ReadInfoElement(Element infoElement)
{
Element element;
while (_stream.Position < infoElement.EndPosition && (element = ReadElement()) != null)
{
switch (element.Id)
{
case ElementId.TimecodeScale:
// Timestamp scale in nanoseconds (1.000.000 means all timestamps in the segment are expressed in milliseconds)
_timecodeScale = (int)ReadUInt((int)element.DataSize);
break;
case ElementId.Duration:
// Duration of the segment (based on TimecodeScale)
_duration = element.DataSize == 4 ? ReadFloat32() : ReadFloat64();
_duration /= _timecodeScale * 1000000.0;
break;
default:
_stream.Seek(element.DataSize, SeekOrigin.Current);
break;
}
}
}
private void ReadContentEncodingElement(Element contentEncodingElement, ref int contentCompressionAlgorithm, ref int contentEncodingType)
{
Element element;
while (_stream.Position < contentEncodingElement.EndPosition && (element = ReadElement()) != null)
{
switch (element.Id)
{
case ElementId.ContentEncodingOrder:
var contentEncodingOrder = ReadUInt((int)element.DataSize);
System.Diagnostics.Debug.WriteLine("ContentEncodingOrder: " + contentEncodingOrder);
break;
case ElementId.ContentEncodingScope:
var contentEncodingScope = ReadUInt((int)element.DataSize);
System.Diagnostics.Debug.WriteLine("ContentEncodingScope: " + contentEncodingScope);
break;
case ElementId.ContentEncodingType:
contentEncodingType = (int)ReadUInt((int)element.DataSize);
break;
case ElementId.ContentCompression:
Element compElement;
while (_stream.Position < element.EndPosition && (compElement = ReadElement()) != null)
{
switch (compElement.Id)
{
case ElementId.ContentCompAlgo:
contentCompressionAlgorithm = (int)ReadUInt((int)compElement.DataSize);
break;
case ElementId.ContentCompSettings:
var contentCompSettings = ReadUInt((int)compElement.DataSize);
System.Diagnostics.Debug.WriteLine("ContentCompSettings: " + contentCompSettings);
break;
default:
_stream.Seek(element.DataSize, SeekOrigin.Current);
break;
}
}
break;
default:
_stream.Seek(element.DataSize, SeekOrigin.Current);
break;
}
}
}
private void ReadCluster(Element clusterElement)
{
long clusterTimeCode = 0;
Element element;
while (_stream.Position < clusterElement.EndPosition && (element = ReadElement()) != null)
{
switch (element.Id)
{
case ElementId.Timecode:
clusterTimeCode = (long)ReadUInt((int)element.DataSize);
break;
case ElementId.BlockGroup:
ReadBlockGroupElement(element, clusterTimeCode);
break;
case ElementId.SimpleBlock:
var subtitle = ReadSubtitleBlock(element, clusterTimeCode);
if (subtitle != null)
{
_subtitleRip.Add(subtitle);
}
break;
default:
_stream.Seek(element.DataSize, SeekOrigin.Current);
break;
}
}
}
private void ReadBlockGroupElement(Element clusterElement, long clusterTimeCode)
{
MatroskaSubtitle subtitle = null;
Element element;
while (_stream.Position < clusterElement.EndPosition && (element = ReadElement()) != null)
{
switch (element.Id)
{
case ElementId.Block:
subtitle = ReadSubtitleBlock(element, clusterTimeCode);
if (subtitle == null)
{
return;
}
_subtitleRip.Add(subtitle);
break;
case ElementId.BlockDuration:
var duration = (long)ReadUInt((int)element.DataSize);
if (subtitle != null)
{
subtitle.Duration = duration;
}
break;
default:
_stream.Seek(element.DataSize, SeekOrigin.Current);
break;
}
}
}
private long FindTrackStartInCluster(Element cluster, int targetTrackNumber)
{
long clusterTimeCode = 0L;
long trackStartTime = -1L;
bool done = false;
Element element;
while (_stream.Position < cluster.EndPosition && (element = ReadElement()) != null && !done)
{
switch (element.Id)
{
case ElementId.None:
done = true;
break;
case ElementId.Timecode:
// Absolute timestamp of the cluster (based on TimecodeScale)
clusterTimeCode = (long)ReadUInt((int)element.DataSize);
break;
case ElementId.BlockGroup:
ReadBlockGroupElement(element, clusterTimeCode);
break;
case ElementId.SimpleBlock:
var trackNumber = (int)ReadVariableLengthUInt();
if (trackNumber == targetTrackNumber)
{
// Timecode (relative to Cluster timecode, signed int16)
trackStartTime = ReadInt16();
done = true;
}
break;
}
_stream.Seek(element.EndPosition, SeekOrigin.Begin);
}
return (clusterTimeCode + trackStartTime) * _timecodeScale / 1000000;
}
