protected string _privateData; // Either "CodecPrivateData" or "WaveFormatEx"
#endregion Fields
#region Constructors
/// <summary>
/// Prepate a SMIL generator
/// </summary>
/// <param name="FileRoot">
/// Start of the media file name (used by IIS to create archive files).
/// This will be appended with bitrate and dot-extension.
/// </param>
public SmilGenerator(string FileRoot, MediaStream SourceStream)
{
switch (SourceStream.FourCC) {
case "mp4a":
_fourCC = "mp4a";
Height = 0;
Width = 0;
break;
case "mp3a":
_fourCC = "mp3a";
Height = 0;
Width = 0;
break;
case "avc1":
case "H264":
_fourCC = "H264"; // use the Microsoft form, as this is for sending to IIS & Silverlight.
Height = SourceStream.Height;
Width = SourceStream.Width;
break;
default: throw new ArgumentException("Stream type " + SourceStream.FourCC + " is not supported", "SourceStream");
}
_channel = SourceStream.TrackId;
_fileRoot = FileRoot;
}
/// <summary>
/// Remove any frames with zero length.
/// Zero length frames kill the live stream.
/// </summary>
private void SanitiseStream(MediaStream stream)
{
lock (SyncRoot) {
var src = new List<GenericMediaFrame>(stream.Frames);
stream.Frames.Clear();
foreach (var frame in src) {
if (frame.FrameDuration < 1) continue;
stream.Frames.Add(frame);
}
}
}
/// <summary>
/// Pushes a set of frames to IIS. Will trigger a connect if needed.
/// </summary>
private void PushStream(MediaStream stream, FileRoot TargetMp4fFile)
{
if (stream == null || stream.Frames == null) return; // no frames.
SanitiseStream(stream);
if (stream.Frames.Count < 1) return; // no frames.
if (!PushServer.IsConnected(stream.TrackId))
ConnectAndPushHeaders(stream, TargetMp4fFile);
// set start-of-fragment time from PTS
stream.Offset = stream.Frames[0].FramePresentationTime - stream.Frames[0].FrameDuration;
// Push the fragment
var fragment_handler = TargetMp4fFile.GenerateFragment(stream);
PushServer.PushData(stream.TrackId, fragment_handler.MoofData());
PushServer.PushData(stream.TrackId, fragment_handler.MdatData());
}
/// <summary>
/// Used once per connection, this opens a long-life HTTP stream
/// and pushes the very basic MP4 parts needed to get IIS working.
/// </summary>
private void ConnectAndPushHeaders(MediaStream stream, FileRoot TargetMp4fFile)
{
SmilGenerator smil = new SmilGenerator("HCS Encoder by Iain Ballard.", stream);
smil.ApproxBitrate = stream.Bitrate;
MP4_Mangler.ExtraBoxes.SmoothSmil ssmil = new MP4_Mangler.ExtraBoxes.SmoothSmil(smil.Generate());
PushServer.Connect(stream.TrackId); // This pushes to the subpath: Streams({id}-stream{index})
// push headers (only done once per track)
// each one needs it's own HTTP Chunk, so don't concat!
PushServer.PushData(stream.TrackId, TargetMp4fFile.GenerateFileSpec());
PushServer.PushData(stream.TrackId, ssmil.deepData());
PushServer.PushData(stream.TrackId, TargetMp4fFile.GenerateHeaders());
}
/// <summary>
/// Generate a pair of 'moof' and 'mdat' atoms for the given stream.
/// The stream should contains a populated list of frame data, otherwise output will be empty.
/// Keeps track of fragment index. Does not write to file. Does not remove frames. Does not adjust offset time.
/// </summary>
public FragmentBoxes.MediaFragmentHandler GenerateFragment(MediaStream Stream)
{
if (Stream.Frames == null || Stream.Frames.Count < 1) throw new Exception("Stream was empty");
FragmentBoxes.MediaFragmentHandler output = new MP4_Mangler.FragmentBoxes.MediaFragmentHandler((uint)Stream.FragmentNumber, Stream.Offset);
Stream.FragmentNumber++;
foreach (var frame in Stream.Frames) {
output.AddFrame((uint)Stream.TrackId, frame);
}
Stream.Frames.Clear();
return output;
}
/// <summary>
/// Store the frames of a stream in the KnownStreams cache, adding a new entry if needed.
/// If there is a file open, then new streams will be refused with an argument exception
/// </summary>
private MediaStream CacheStreamFrames(MediaStream SourceStream)
{
var dst_stream = KnownStreams.Where(a => a.TrackId == SourceStream.TrackId).FirstOrDefault();
if (dst_stream == null) { // not a known stream, so add it.
if (ActiveFile != null) throw new ArgumentException("Can't add new streams to an open file. Try adding your streams first, then open the file once all streams are known", "SourceStream");
dst_stream = new MediaStream();
dst_stream.FourCC = SourceStream.FourCC;
dst_stream.Frames = new List<GenericMediaFrame>(SourceStream.Frames);
dst_stream.Height = SourceStream.Height;
dst_stream.TrackId = SourceStream.TrackId;
dst_stream.Width = SourceStream.Width;
KnownStreams.Add(dst_stream);
} else {
dst_stream.Frames.AddRange(SourceStream.Frames);
}
return dst_stream;
}
/// <summary>
/// Write the frames of a stream to a file if one is open or to memory if not.
/// </summary>
public void WriteStream(MediaStream SourceStream)
{
var dst_stream = CacheStreamFrames(SourceStream);
if (ActiveFile == null) return; // No file to write.
// Write to file system (writes, flushes and re-closes)
using (BinaryWriter wr = new BinaryWriter(ActiveFile.Open(FileMode.Append, FileAccess.Write, FileShare.Read))) {
wr.Write(GenerateFragment(dst_stream).FormatData()); // Write any waiting frames, plus the newly added ones
wr.Flush();
wr.Close(); // closes the file as well.
}
dst_stream.Frames.Clear(); // OK, we've handled these -- so dump the caches
}
