public bool TryParseContentType(byte[] header, out string content_type, out string mime_type)
 {
     try {
         using (var stream = new MemoryStream(header)) {
             var elt = Element.ReadHeader(stream);
             if (4 < elt.ID.Length || 8 < elt.Size.Length ||
                 !elt.ID.BinaryEquals(Elements.EBML))
             {
                 content_type = null;
                 mime_type    = null;
                 return(false);
             }
             elt.ReadBody(stream);
             var ebml = new EBML(elt);
             if (ebml.DocType == "webm")
             {
                 content_type = "WEBM";
                 mime_type    = "video/webm";
             }
             else
             {
                 content_type = "MKV";
                 mime_type    = "video/x-matroska";
             }
             return(true);
         }
     }
     catch (EndOfStreamException) {
         content_type = null;
         mime_type    = null;
         return(false);
     }
 }
        public ParsedContent Read(Stream stream)
        {
            var res       = new ParsedContent();
            var bodies    = new List <Element>();
            var info      = new AtomCollection(Channel.ChannelInfo.Extra);
            var processed = false;
            var eos       = false;

            while (!eos)
            {
                var start_pos = stream.Position;
                try {
                    var elt = Element.ReadHeader(stream);
                    if (ebml.MaxIDLength < elt.ID.Length ||
                        ebml.MaxSizeLength < elt.Size.Length)
                    {
                        throw new BadDataException();
                    }
                    switch (state)
                    {
                    case ReaderState.EBML:
                        if (elt.ID.BinaryEquals(Elements.EBML))
                        {
                            elt.ReadBody(stream);
                            ebml  = new EBML(elt);
                            state = ReaderState.Segment;
                        }
                        else
                        {
                            throw new BadDataException();
                        }
                        break;

                    case ReaderState.Segment:
                        if (elt.ID.BinaryEquals(Elements.Segment))
                        {
                            segment = new Segment(elt);
                            state   = ReaderState.EndOfHeader;
                        }
                        else if (elt.ID.BinaryEquals(Elements.EBML))
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.EBML;
                            continue;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Void) ||
                                 elt.ID.BinaryEquals(Elements.CRC32))
                        {
                            elt.ReadBody(stream);
                        }
                        else
                        {
                            throw new BadDataException();
                        }
                        break;

                    case ReaderState.EndOfHeader:
                        if (elt.ID.BinaryEquals(Elements.Segment))
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.Segment;
                            continue;
                        }
                        else if (elt.ID.BinaryEquals(Elements.EBML))
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.EBML;
                            continue;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Cluster))
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.Cluster;
                            clusters.Clear();
                            MemoryStream header;
                            using (header = new MemoryStream()) {
                                ebml.Element.Write(header);
                                segment.Element.Write(header);
                                foreach (var c in segment.HeaderElements)
                                {
                                    c.Write(header);
                                }
                            }
                            res.ContentHeader = new Content(0, header.ToArray());
                            if (ebml.DocType == "webm")
                            {
                                info.SetChanInfoType("WEBM");
                                info.SetChanInfoStreamType("video/webm");
                                info.SetChanInfoStreamExt(".webm");
                            }
                            else
                            {
                                info.SetChanInfoType("MKV");
                                info.SetChanInfoStreamType("video/x-matroska");
                                info.SetChanInfoStreamExt(".mkv");
                            }
                            res.ChannelInfo = new ChannelInfo(info);
                        }
                        else
                        {
                            elt.ReadBody(stream);
                            segment.AddHeader(elt);
                        }
                        break;

                    case ReaderState.Cluster:
                        if (elt.ID.BinaryEquals(Elements.Segment))
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.Segment;
                            continue;
                        }
                        else if (elt.ID.BinaryEquals(Elements.EBML))
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.EBML;
                            continue;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Cluster))
                        {
                            if (clusters.Count > 0)
                            {
                                var timespan = clusters.Sum(c => c.Timespan);
                                if (timespan >= 30.0)
                                {
                                    var sz   = clusters.Sum(c => c.Timespan > 0 ? c.BlockSize : 0);
                                    var kbps = (int)((sz * 8 / timespan + 900) / 1000.0);
                                    info.SetChanInfoBitrate(kbps);
                                    res.ChannelInfo = new ChannelInfo(info);
                                    while (clusters.Count > 1)
                                    {
                                        clusters.RemoveFirst();
                                    }
                                }
                            }
                            var cluster = new Cluster(elt);
                            clusters.AddLast(cluster);
                            bodies.Add(elt);
                            state = ReaderState.Timecode;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Void) ||
                                 elt.ID.BinaryEquals(Elements.CRC32))
                        {
                            elt.ReadBody(stream);
                            bodies.Add(elt);
                        }
                        else
                        {
                            throw new BadDataException();
                        }
                        break;

                    case ReaderState.Timecode:
                        if (elt.ID.BinaryEquals(Elements.Segment))
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.Segment;
                            continue;
                        }
                        else if (elt.ID.BinaryEquals(Elements.EBML))
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.EBML;
                            continue;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Cluster))
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.Cluster;
                            continue;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Timecode))
                        {
                            elt.ReadBody(stream);
                            if (clusters.Last != null)
                            {
                                clusters.Last.Value.Timecode =
                                    Element.ReadUInt(new MemoryStream(elt.Data), elt.Data.Length) * (segment.TimecodeScale / 1000000000.0);
                                if (clusters.Count > 1)
                                {
                                    clusters.Last.Previous.Value.Timespan = clusters.Last.Value.Timecode - clusters.Last.Previous.Value.Timecode;
                                }
                            }
                            bodies.Add(elt);
                            state = ReaderState.Block;
                        }
                        else if (elt.ID.BinaryEquals(Elements.SimpleBlock) ||
                                 elt.ID.BinaryEquals(Elements.BlockGroup))
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.Block;
                            continue;
                        }
                        else
                        {
                            elt.ReadBody(stream);
                            bodies.Add(elt);
                        }
                        break;

                    case ReaderState.Block:
                        if (elt.ID.BinaryEquals(Elements.Segment))
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.Segment;
                            continue;
                        }
                        else if (elt.ID.BinaryEquals(Elements.EBML))
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.EBML;
                            continue;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Cluster))
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.Cluster;
                            continue;
                        }
                        else if ((elt.ID.BinaryEquals(Elements.SimpleBlock) ||
                                  elt.ID.BinaryEquals(Elements.BlockGroup)) &&
                                 (clusters.Last.Value.BlockID == null ||
                                  elt.ID.BinaryEquals(clusters.Last.Value.BlockID)))
                        {
                            elt.ReadBody(stream);
                            clusters.Last.Value.BlockSize += elt.Size.Value;
                            clusters.Last.Value.BlockID    = elt.ID.Binary;
                            bodies.Add(elt);
                        }
                        else if (clusters.Last.Value.BlockID == null)
                        {
                            elt.ReadBody(stream);
                            bodies.Add(elt);
                        }
                        else
                        {
                            stream.Position = elt.Position;
                            state           = ReaderState.Cluster;
                            continue;
                        }
                        break;
                    }
                    processed = true;
                }
                catch (EndOfStreamException) {
                    if (!processed)
                    {
                        throw;
                    }
                    stream.Position = start_pos;
                    eos             = true;
                }
                catch (BadDataException) {
                    stream.Position = start_pos + 1;
                }
            }
            if (res.ContentHeader != null)
            {
                position =
                    res.ContentHeader.Position +
                    res.ContentHeader.Data.Length;
            }
            if (bodies.Count > 0)
            {
                res.Contents = new List <Content>();
                foreach (var body in bodies)
                {
                    MemoryStream s;
                    using (s = new MemoryStream()) {
                        body.Write(s);
                    }
                    var data = s.ToArray();
                    res.Contents.Add(new Content(position, data));
                    position += data.Length;
                }
            }
            return(res);
        }
Example #3
0
 public ParsedContent Read(Stream stream)
 {
     var res = new ParsedContent();
       var bodies = new List<Element>();
       var info = new AtomCollection(Channel.ChannelInfo.Extra);
       var processed = false;
       var eos = false;
       while (!eos) {
     var start_pos = stream.Position;
     try {
       var elt = Element.ReadHeader(stream);
       if (ebml.MaxIDLength  <elt.ID.Length ||
       ebml.MaxSizeLength<elt.Size.Length) {
     throw new BadDataException();
       }
       switch (state) {
       case ReaderState.EBML:
     if (elt.ID.BinaryEquals(Elements.EBML)) {
       elt.ReadBody(stream);
       ebml = new EBML(elt);
       state = ReaderState.Segment;
     }
     else {
       throw new BadDataException();
     }
     break;
       case ReaderState.Segment:
     if (elt.ID.BinaryEquals(Elements.Segment)) {
       segment = new Segment(elt);
       state = ReaderState.EndOfHeader;
     }
     else if (elt.ID.BinaryEquals(Elements.EBML)) {
       stream.Position = elt.Position;
       state = ReaderState.EBML;
       continue;
     }
     else if (elt.ID.BinaryEquals(Elements.Void) ||
              elt.ID.BinaryEquals(Elements.CRC32)) {
       elt.ReadBody(stream);
     }
     else {
       throw new BadDataException();
     }
     break;
       case ReaderState.EndOfHeader:
     if (elt.ID.BinaryEquals(Elements.Segment)) {
       stream.Position = elt.Position;
       state = ReaderState.Segment;
       continue;
     }
     else if (elt.ID.BinaryEquals(Elements.EBML)) {
       stream.Position = elt.Position;
       state = ReaderState.EBML;
       continue;
     }
     else if (elt.ID.BinaryEquals(Elements.Cluster)) {
       stream.Position = elt.Position;
       state = ReaderState.Cluster;
       clusters.Clear();
       MemoryStream header;
       using (header=new MemoryStream()) {
         ebml.Element.Write(header);
         segment.Element.Write(header);
         foreach (var c in segment.HeaderElements) {
           c.Write(header);
         }
       }
       streamIndex = Channel.GenerateStreamID();
       streamOrigin = DateTime.Now;
       res.ContentHeader = new Content(streamIndex, TimeSpan.Zero, 0, header.ToArray());
       if (ebml.DocType=="webm") {
         info.SetChanInfoType("WEBM");
         info.SetChanInfoStreamType("video/webm");
         info.SetChanInfoStreamExt(".webm");
       }
       else {
         info.SetChanInfoType("MKV");
         info.SetChanInfoStreamType("video/x-matroska");
         info.SetChanInfoStreamExt(".mkv");
       }
       res.ChannelInfo = new ChannelInfo(info);
     }
     else {
       elt.ReadBody(stream);
       segment.AddHeader(elt);
     }
     break;
       case ReaderState.Cluster:
     if (elt.ID.BinaryEquals(Elements.Segment)) {
       stream.Position = elt.Position;
       state = ReaderState.Segment;
       continue;
     }
     else if (elt.ID.BinaryEquals(Elements.EBML)) {
       stream.Position = elt.Position;
       state = ReaderState.EBML;
       continue;
     }
     else if (elt.ID.BinaryEquals(Elements.Cluster)) {
       if (clusters.Count>0) {
         var timespan = clusters.Sum(c => c.Timespan);
         if (timespan>=30.0) {
           var sz = clusters.Sum(c => c.Timespan>0 ? c.BlockSize : 0);
           var kbps = (int)((sz*8/timespan+900) / 1000.0);
           info.SetChanInfoBitrate(kbps);
           res.ChannelInfo = new ChannelInfo(info);
           while (clusters.Count>1) clusters.RemoveFirst();
         }
       }
       var cluster = new Cluster(elt);
       clusters.AddLast(cluster);
       bodies.Add(elt);
       state = ReaderState.Timecode;
     }
     else if (elt.ID.BinaryEquals(Elements.Void) ||
              elt.ID.BinaryEquals(Elements.CRC32)) {
       elt.ReadBody(stream);
       bodies.Add(elt);
     }
     else {
       throw new BadDataException();
     }
     break;
       case ReaderState.Timecode:
     if (elt.ID.BinaryEquals(Elements.Segment)) {
       stream.Position = elt.Position;
       state = ReaderState.Segment;
       continue;
     }
     else if (elt.ID.BinaryEquals(Elements.EBML)) {
       stream.Position = elt.Position;
       state = ReaderState.EBML;
       continue;
     }
     else if (elt.ID.BinaryEquals(Elements.Cluster)) {
       stream.Position = elt.Position;
       state = ReaderState.Cluster;
       continue;
     }
     else if (elt.ID.BinaryEquals(Elements.Timecode)) {
       elt.ReadBody(stream);
       if (clusters.Last!=null) {
         clusters.Last.Value.Timecode =
           Element.ReadUInt(new MemoryStream(elt.Data), elt.Data.Length)*(segment.TimecodeScale/1000000000.0);
         if (clusters.Count>1) {
           clusters.Last.Previous.Value.Timespan = clusters.Last.Value.Timecode - clusters.Last.Previous.Value.Timecode;
         }
       }
       bodies.Add(elt);
       state = ReaderState.Block;
     }
     else if (elt.ID.BinaryEquals(Elements.SimpleBlock) ||
              elt.ID.BinaryEquals(Elements.BlockGroup)) {
       stream.Position = elt.Position;
       state = ReaderState.Block;
       continue;
     }
     else {
       elt.ReadBody(stream);
       bodies.Add(elt);
     }
     break;
       case ReaderState.Block:
     if (elt.ID.BinaryEquals(Elements.Segment)) {
       stream.Position = elt.Position;
       state = ReaderState.Segment;
       continue;
     }
     else if (elt.ID.BinaryEquals(Elements.EBML)) {
       stream.Position = elt.Position;
       state = ReaderState.EBML;
       continue;
     }
     else if (elt.ID.BinaryEquals(Elements.Cluster)) {
       stream.Position = elt.Position;
       state = ReaderState.Cluster;
       continue;
     }
     else if ((elt.ID.BinaryEquals(Elements.SimpleBlock) ||
               elt.ID.BinaryEquals(Elements.BlockGroup)) &&
              (clusters.Last.Value.BlockID==null ||
               elt.ID.BinaryEquals(clusters.Last.Value.BlockID))) {
       elt.ReadBody(stream);
       clusters.Last.Value.BlockSize += elt.Size.Value;
       clusters.Last.Value.BlockID    = elt.ID.Binary;
       bodies.Add(elt);
     }
     else if (clusters.Last.Value.BlockID==null) {
       elt.ReadBody(stream);
       bodies.Add(elt);
     }
     else {
       stream.Position = elt.Position;
       state = ReaderState.Cluster;
       continue;
     }
     break;
       }
       processed = true;
     }
     catch (EndOfStreamException) {
       if (!processed) throw;
       stream.Position = start_pos;
       eos = true;
     }
     catch (BadDataException) {
       stream.Position = start_pos+1;
     }
       }
       if (res.ContentHeader!=null) {
     position =
       res.ContentHeader.Position +
       res.ContentHeader.Data.Length;
       }
       if (bodies.Count>0) {
     res.Contents = new List<Content>();
     foreach (var body in bodies) {
       MemoryStream s;
       using (s=new MemoryStream()) {
     body.Write(s);
       }
       var data = s.ToArray();
       res.Contents.Add(new Content(streamIndex, DateTime.Now-streamOrigin, position, data));
       position += data.Length;
     }
       }
       return res;
 }
        public async Task ReadAsync(IContentSink sink, Stream stream, CancellationToken cancel_token)
        {
            var state          = ReaderState.EBML;
            var position       = 0L;
            var stream_index   = -1;
            var stream_origin  = DateTime.Now;
            var timecode_scale = 1000000.0;
            var ebml           = new EBML();
            var clusters       = new LinkedList <Cluster>();
            var headers        = new List <Element>();

            var eos = false;

            while (!eos)
            {
                try {
                    var elt = await Element.ReadHeaderAsync(stream, cancel_token).ConfigureAwait(false);

                    if (ebml.MaxIDLength < elt.ID.Length ||
                        ebml.MaxSizeLength < elt.Size.Length)
                    {
                        throw new BadDataException();
                    }
parse_retry:
                    switch (state)
                    {
                    case ReaderState.EBML:
                        if (elt.ID.BinaryEquals(Elements.EBML))
                        {
                            await elt.ReadBodyAsync(stream, cancel_token).ConfigureAwait(false);

                            headers.Clear();
                            headers.Add(elt);
                            ebml  = new EBML(elt);
                            state = ReaderState.Segment;
                        }
                        else
                        {
                            throw new BadDataException();
                        }
                        break;

                    case ReaderState.Segment:
                        if (elt.ID.BinaryEquals(Elements.Segment))
                        {
                            headers.Add(elt);
                            state = ReaderState.EndOfHeader;
                        }
                        else if (elt.ID.BinaryEquals(Elements.EBML))
                        {
                            state = ReaderState.EBML;
                            goto parse_retry;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Void) ||
                                 elt.ID.BinaryEquals(Elements.CRC32))
                        {
                            await elt.ReadBodyAsync(stream, cancel_token).ConfigureAwait(false);

                            headers.Add(elt);
                        }
                        else
                        {
                            throw new BadDataException();
                        }
                        break;

                    case ReaderState.EndOfHeader:
                        if (elt.ID.BinaryEquals(Elements.Segment))
                        {
                            state = ReaderState.Segment;
                            goto parse_retry;
                        }
                        else if (elt.ID.BinaryEquals(Elements.EBML))
                        {
                            state = ReaderState.EBML;
                            goto parse_retry;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Cluster))
                        {
                            clusters.Clear();
                            MemoryStream header;
                            using (header = new MemoryStream()) {
                                foreach (var c in headers)
                                {
                                    c.Write(header);
                                }
                            }
                            headers.Clear();

                            stream_index  = Channel.GenerateStreamID();
                            stream_origin = DateTime.Now;
                            position      = 0;
                            sink.OnContentHeader(
                                new Content(stream_index, TimeSpan.Zero, 0, header.ToArray(), PCPChanPacketContinuation.None)
                                );
                            position += header.ToArray().LongLength;
                            var info = new AtomCollection();
                            if (ebml.DocType == "webm")
                            {
                                info.SetChanInfoType("WEBM");
                                info.SetChanInfoStreamType("video/webm");
                                info.SetChanInfoStreamExt(".webm");
                            }
                            else
                            {
                                info.SetChanInfoType("MKV");
                                info.SetChanInfoStreamType("video/x-matroska");
                                info.SetChanInfoStreamExt(".mkv");
                            }
                            sink.OnChannelInfo(new ChannelInfo(info));

                            state = ReaderState.Cluster;
                            goto parse_retry;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Info))
                        {
                            await elt.ReadBodyAsync(stream, cancel_token).ConfigureAwait(false);

                            var s = new MemoryStream(elt.Data);
                            while (s.Position < s.Length)
                            {
                                var child = Element.ReadHeader(s);
                                if (child.ID.BinaryEquals(Elements.TimecodeScale))
                                {
                                    timecode_scale = Element.ReadUInt(s, child.Size.Value) * 1.0;
                                }
                                else
                                {
                                    child.ReadBody(s);
                                }
                            }
                            headers.Add(elt);
                        }
                        else
                        {
                            await elt.ReadBodyAsync(stream, cancel_token).ConfigureAwait(false);

                            headers.Add(elt);
                        }
                        break;

                    case ReaderState.Cluster:
                        if (elt.ID.BinaryEquals(Elements.Segment))
                        {
                            state = ReaderState.Segment;
                            goto parse_retry;
                        }
                        else if (elt.ID.BinaryEquals(Elements.EBML))
                        {
                            state = ReaderState.EBML;
                            goto parse_retry;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Cluster))
                        {
                            if (clusters.Count > 0)
                            {
                                var timespan = clusters.Sum(c => c.Timespan);
                                if (timespan >= 30.0)
                                {
                                    var sz   = clusters.Sum(c => c.Timespan > 0 ? c.BlockSize : 0);
                                    var kbps = (int)((sz * 8 / timespan + 900) / 1000.0);
                                    var info = new AtomCollection();
                                    info.SetChanInfoBitrate(kbps);
                                    sink.OnChannelInfo(new ChannelInfo(info));
                                    while (clusters.Count > 1)
                                    {
                                        clusters.RemoveFirst();
                                    }
                                }
                            }
                            var cluster = new Cluster(elt);
                            clusters.AddLast(cluster);
                            sink.OnContent(
                                new Content(stream_index, DateTime.Now - stream_origin, position, elt.ToArray(), PCPChanPacketContinuation.None)
                                );
                            position += elt.ByteSize;
                            state     = ReaderState.Timecode;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Void) ||
                                 elt.ID.BinaryEquals(Elements.CRC32))
                        {
                            await elt.ReadBodyAsync(stream, cancel_token).ConfigureAwait(false);

                            sink.OnContent(
                                new Content(stream_index, DateTime.Now - stream_origin, position, elt.ToArray(), PCPChanPacketContinuation.None)
                                );
                            position += elt.ByteSize;
                        }
                        else
                        {
                            throw new BadDataException();
                        }
                        break;

                    case ReaderState.Timecode:
                        if (elt.ID.BinaryEquals(Elements.Segment))
                        {
                            state = ReaderState.Segment;
                            goto parse_retry;
                        }
                        else if (elt.ID.BinaryEquals(Elements.EBML))
                        {
                            state = ReaderState.EBML;
                            goto parse_retry;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Cluster))
                        {
                            state = ReaderState.Cluster;
                            goto parse_retry;
                        }
                        else if (elt.ID.BinaryEquals(Elements.SimpleBlock) ||
                                 elt.ID.BinaryEquals(Elements.BlockGroup))
                        {
                            state = ReaderState.Block;
                            goto parse_retry;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Timecode))
                        {
                            await elt.ReadBodyAsync(stream, cancel_token).ConfigureAwait(false);

                            if (clusters.Last != null)
                            {
                                clusters.Last.Value.Timecode =
                                    Element.ReadUInt(new MemoryStream(elt.Data), elt.Data.Length) * (timecode_scale / 1000000000.0);
                                if (clusters.Count > 1)
                                {
                                    clusters.Last.Previous.Value.Timespan = clusters.Last.Value.Timecode - clusters.Last.Previous.Value.Timecode;
                                }
                            }
                            sink.OnContent(
                                new Content(stream_index, DateTime.Now - stream_origin, position, elt.ToArray(), PCPChanPacketContinuation.None)
                                );
                            position += elt.ByteSize;
                            state     = ReaderState.Block;
                        }
                        else
                        {
                            await elt.ReadBodyAsync(stream, cancel_token).ConfigureAwait(false);

                            sink.OnContent(
                                new Content(stream_index, DateTime.Now - stream_origin, position, elt.ToArray(), PCPChanPacketContinuation.None)
                                );
                            position += elt.ByteSize;
                        }
                        break;

                    case ReaderState.Block:
                        if (elt.ID.BinaryEquals(Elements.Segment))
                        {
                            state = ReaderState.Segment;
                            goto parse_retry;
                        }
                        else if (elt.ID.BinaryEquals(Elements.EBML))
                        {
                            state = ReaderState.EBML;
                            goto parse_retry;
                        }
                        else if (elt.ID.BinaryEquals(Elements.Cluster))
                        {
                            state = ReaderState.Cluster;
                            goto parse_retry;
                        }
                        else if ((elt.ID.BinaryEquals(Elements.SimpleBlock) ||
                                  elt.ID.BinaryEquals(Elements.BlockGroup)) &&
                                 (clusters.Last.Value.BlockID == null ||
                                  elt.ID.BinaryEquals(clusters.Last.Value.BlockID)))
                        {
                            await elt.ReadBodyAsync(stream, cancel_token).ConfigureAwait(false);

                            clusters.Last.Value.BlockSize += elt.Size.Value;
                            clusters.Last.Value.BlockID    = elt.ID.Binary;
                            sink.OnContent(
                                new Content(stream_index, DateTime.Now - stream_origin, position, elt.ToArray(), PCPChanPacketContinuation.None)
                                );
                            position += elt.ByteSize;
                        }
                        else if (clusters.Last.Value.BlockID == null)
                        {
                            await elt.ReadBodyAsync(stream, cancel_token).ConfigureAwait(false);

                            sink.OnContent(
                                new Content(stream_index, DateTime.Now - stream_origin, position, elt.ToArray(), PCPChanPacketContinuation.None)
                                );
                            position += elt.ByteSize;
                        }
                        else
                        {
                            state = ReaderState.Cluster;
                            goto parse_retry;
                        }
                        break;
                    }
                }
                catch (EndOfStreamException) {
                    eos = true;
                }
                catch (BadDataException) {
                }
            }
        }
 public bool TryParseContentType(byte[] header, out string content_type, out string mime_type)
 {
   try {
     using (var stream=new MemoryStream(header)) {
       var elt = Element.ReadHeader(stream);
       if (4<elt.ID.Length || 8<elt.Size.Length ||
           !elt.ID.BinaryEquals(Elements.EBML)) {
         content_type = null;
         mime_type    = null;
         return false;
       }
       elt.ReadBody(stream);
       var ebml = new EBML(elt);
       if (ebml.DocType=="webm") {
         content_type = "WEBM";
         mime_type = "video/webm";
       }
       else {
         content_type = "MKV";
         mime_type = "video/x-matroska";
       }
       return true;
     }
   }
   catch (EndOfStreamException) {
     content_type = null;
     mime_type    = null;
     return false;
   }
 }
    public async Task ReadAsync(IContentSink sink, Stream stream, CancellationToken cancel_token)
    {
      var state = ReaderState.EBML;
      var position = 0L;
      var stream_index = -1;
      var stream_origin = DateTime.Now;
      var timecode_scale = 1000000.0;
      var ebml     = new EBML();
      var clusters = new LinkedList<Cluster>();
      var headers  = new List<Element>();

      var eos = false;
      while (!eos) {
        try {
          var elt = await Element.ReadHeaderAsync(stream, cancel_token);
          if (ebml.MaxIDLength  <elt.ID.Length ||
              ebml.MaxSizeLength<elt.Size.Length) {
            throw new BadDataException();
          }
        parse_retry:
          switch (state) {
          case ReaderState.EBML:
            if (elt.ID.BinaryEquals(Elements.EBML)) {
              await elt.ReadBodyAsync(stream, cancel_token);
              headers.Clear();
              headers.Add(elt);
              ebml = new EBML(elt);
              state = ReaderState.Segment;
            }
            else {
              throw new BadDataException();
            }
            break;
          case ReaderState.Segment:
            if (elt.ID.BinaryEquals(Elements.Segment)) {
              headers.Add(elt);
              state = ReaderState.EndOfHeader;
            }
            else if (elt.ID.BinaryEquals(Elements.EBML)) {
              state = ReaderState.EBML;
              goto parse_retry;
            }
            else if (elt.ID.BinaryEquals(Elements.Void) ||
                     elt.ID.BinaryEquals(Elements.CRC32)) {
              await elt.ReadBodyAsync(stream, cancel_token);
              headers.Add(elt);
            }
            else {
              throw new BadDataException();
            }
            break;
          case ReaderState.EndOfHeader:
            if (elt.ID.BinaryEquals(Elements.Segment)) {
              state = ReaderState.Segment;
              goto parse_retry;
            }
            else if (elt.ID.BinaryEquals(Elements.EBML)) {
              state = ReaderState.EBML;
              goto parse_retry;
            }
            else if (elt.ID.BinaryEquals(Elements.Cluster)) {
              clusters.Clear();
              MemoryStream header;
              using (header=new MemoryStream()) {
                foreach (var c in headers) {
                  c.Write(header);
                }
              }
              headers.Clear();

              stream_index  = Channel.GenerateStreamID();
              stream_origin = DateTime.Now;
              position = 0;
              sink.OnContentHeader(
                new Content(stream_index, TimeSpan.Zero, 0, header.ToArray())
              );
              position += header.ToArray().LongLength;
              var info = new AtomCollection();
              if (ebml.DocType=="webm") {
                info.SetChanInfoType("WEBM");
                info.SetChanInfoStreamType("video/webm");
                info.SetChanInfoStreamExt(".webm");
              }
              else {
                info.SetChanInfoType("MKV");
                info.SetChanInfoStreamType("video/x-matroska");
                info.SetChanInfoStreamExt(".mkv");
              }
              sink.OnChannelInfo(new ChannelInfo(info));

              state = ReaderState.Cluster;
              goto parse_retry;
            }
            else if (elt.ID.BinaryEquals(Elements.Info)) {
              await elt.ReadBodyAsync(stream, cancel_token);
              var s = new MemoryStream(elt.Data);
              while (s.Position<s.Length) {
                var child = Element.ReadHeader(s);
                if (child.ID.BinaryEquals(Elements.TimecodeScale)) {
                  timecode_scale = Element.ReadUInt(s, child.Size.Value) * 1.0;
                }
                else {
                  child.ReadBody(s);
                }
              }
              headers.Add(elt);
            }
            else {
              await elt.ReadBodyAsync(stream, cancel_token);
              headers.Add(elt);
            }
            break;
          case ReaderState.Cluster:
            if (elt.ID.BinaryEquals(Elements.Segment)) {
              state = ReaderState.Segment;
              goto parse_retry;
            }
            else if (elt.ID.BinaryEquals(Elements.EBML)) {
              state = ReaderState.EBML;
              goto parse_retry;
            }
            else if (elt.ID.BinaryEquals(Elements.Cluster)) {
              if (clusters.Count>0) {
                var timespan = clusters.Sum(c => c.Timespan);
                if (timespan>=30.0) {
                  var sz = clusters.Sum(c => c.Timespan>0 ? c.BlockSize : 0);
                  var kbps = (int)((sz*8/timespan+900) / 1000.0);
                  var info = new AtomCollection();
                  info.SetChanInfoBitrate(kbps);
                  sink.OnChannelInfo(new ChannelInfo(info));
                  while (clusters.Count>1) clusters.RemoveFirst();
                }
              }
              var cluster = new Cluster(elt);
              clusters.AddLast(cluster);
              sink.OnContent(
                new Content(stream_index, DateTime.Now-stream_origin, position, elt.ToArray())
              );
              position += elt.ByteSize;
              state = ReaderState.Timecode;
            }
            else if (elt.ID.BinaryEquals(Elements.Void) ||
                     elt.ID.BinaryEquals(Elements.CRC32)) {
              await elt.ReadBodyAsync(stream, cancel_token);
              sink.OnContent(
                new Content(stream_index, DateTime.Now-stream_origin, position, elt.ToArray())
              );
              position += elt.ByteSize;
            }
            else {
              throw new BadDataException();
            }
            break;
          case ReaderState.Timecode:
            if (elt.ID.BinaryEquals(Elements.Segment)) {
              state = ReaderState.Segment;
              goto parse_retry;
            }
            else if (elt.ID.BinaryEquals(Elements.EBML)) {
              state = ReaderState.EBML;
              goto parse_retry;
            }
            else if (elt.ID.BinaryEquals(Elements.Cluster)) {
              state = ReaderState.Cluster;
              goto parse_retry;
            }
            else if (elt.ID.BinaryEquals(Elements.SimpleBlock) ||
                     elt.ID.BinaryEquals(Elements.BlockGroup)) {
              state = ReaderState.Block;
              goto parse_retry;
            }
            else if (elt.ID.BinaryEquals(Elements.Timecode)) {
              await elt.ReadBodyAsync(stream, cancel_token);
              if (clusters.Last!=null) {
                clusters.Last.Value.Timecode =
                  Element.ReadUInt(new MemoryStream(elt.Data), elt.Data.Length)*(timecode_scale/1000000000.0);
                if (clusters.Count>1) {
                  clusters.Last.Previous.Value.Timespan = clusters.Last.Value.Timecode - clusters.Last.Previous.Value.Timecode;
                }
              }
              sink.OnContent(
                new Content(stream_index, DateTime.Now-stream_origin, position, elt.ToArray())
              );
              position += elt.ByteSize;
              state = ReaderState.Block;
            }
            else {
              await elt.ReadBodyAsync(stream, cancel_token);
              sink.OnContent(
                new Content(stream_index, DateTime.Now-stream_origin, position, elt.ToArray())
              );
              position += elt.ByteSize;
            }
            break;
          case ReaderState.Block:
            if (elt.ID.BinaryEquals(Elements.Segment)) {
              state = ReaderState.Segment;
              goto parse_retry;
            }
            else if (elt.ID.BinaryEquals(Elements.EBML)) {
              state = ReaderState.EBML;
              goto parse_retry;
            }
            else if (elt.ID.BinaryEquals(Elements.Cluster)) {
              state = ReaderState.Cluster;
              goto parse_retry;
            }
            else if ((elt.ID.BinaryEquals(Elements.SimpleBlock) ||
                      elt.ID.BinaryEquals(Elements.BlockGroup)) &&
                     (clusters.Last.Value.BlockID==null ||
                      elt.ID.BinaryEquals(clusters.Last.Value.BlockID))) {
              await elt.ReadBodyAsync(stream, cancel_token);
              clusters.Last.Value.BlockSize += elt.Size.Value;
              clusters.Last.Value.BlockID    = elt.ID.Binary;
              sink.OnContent(
                new Content(stream_index, DateTime.Now-stream_origin, position, elt.ToArray())
              );
              position += elt.ByteSize;
            }
            else if (clusters.Last.Value.BlockID==null) {
              await elt.ReadBodyAsync(stream, cancel_token);
              sink.OnContent(
                new Content(stream_index, DateTime.Now-stream_origin, position, elt.ToArray())
              );
              position += elt.ByteSize;
            }
            else {
              state = ReaderState.Cluster;
              goto parse_retry;
            }
            break;
          }
        }
        catch (EndOfStreamException) {
          eos = true;
        }
        catch (BadDataException) {
        }
      }

    }