public unsafe bool TryDecode(ref VideoPacket packet, out VideoFrame frame)
{
if (_videoDecoder == null)
_videoDecoder = new VideoDecoder();
fixed (byte* pData = &packet.Data[0])
{
_avPacket.data = pData;
_avPacket.size = packet.Data.Length;
if (_videoDecoder.TryDecode(ref _avPacket, ref _avFrame))
{
if (_videoConverter == null)
_videoConverter = new VideoConverter(_pixelFormat.ToAVPixelFormat());
byte[] data = _videoConverter.ConvertFrame(ref _avFrame);
frame = new VideoFrame()
{
Timestamp = packet.Timestamp,
Number = packet.FrameNumber,
Width = packet.Width,
Height = packet.Height,
Depth = data.Length / (packet.Width * packet.Height),
PixelFormat = _pixelFormat,
Data = data
};
return true;
}
}
frame = null;
return false;
}
public void EnqueuePacket(VideoPacket packet)
{
if (_skipFrames && packet.FrameType == VideoFrameType.I && _packetQueue.Count > SkipFramesThreshold)
{
Trace.TraceInformation("Skipping {0} frames.", _packetQueue.Count);
_packetQueue.Flush();
}
_packetQueue.Enqueue(packet);
}
private void OnVideoPacketAcquired(VideoPacket packet)
{
if (videoPacketDecoderWorker.IsAlive)
videoPacketDecoderWorker.EnqueuePacket(packet);
}
private void OnVideoPacketAcquired(VideoPacket packet)
{
if (VideoPacketAcquired != null)
VideoPacketAcquired(packet);
}
protected override unsafe void Loop(CancellationToken token)
{
using (var tcpClient = new TcpClient(_configuration.DroneHostname, VideoPort))
using (NetworkStream stream = tcpClient.GetStream())
{
var packet = new VideoPacket();
byte[] packetData = null;
int offset = 0;
int frameStart = 0;
int frameEnd = 0;
var buffer = new byte[FrameBufferSize];
fixed (byte* pBuffer = &buffer[0])
while (token.IsCancellationRequested == false)
{
int read = stream.Read(buffer, offset, NetworkStreamReadSize);
if (read == 0)
{
Thread.Sleep(1);
continue;
}
offset += read;
if (packetData == null)
{
// lookup for a frame start
int maxSearchIndex = offset - sizeof(parrot_video_encapsulation_t);
for (int i = 0; i < maxSearchIndex; i++)
{
if (buffer[i] == 'P' && buffer[i + 1] == 'a' && buffer[i + 2] == 'V' && buffer[i + 3] == 'E')
{
parrot_video_encapsulation_t pve = *(parrot_video_encapsulation_t*)(pBuffer + i);
packetData = new byte[pve.payload_size];
packet = new VideoPacket
{
Timestamp = DateTime.UtcNow.Ticks,
FrameNumber = pve.frame_number,
Width = pve.display_width,
Height = pve.display_height,
FrameType = VideoFrameTypeConverter.Convert(pve.frame_type),
Data = packetData
};
frameStart = i + pve.header_size;
frameEnd = frameStart + packet.Data.Length;
break;
}
}
if (packetData == null)
{
// frame is not detected
offset -= maxSearchIndex;
Array.Copy(buffer, maxSearchIndex, buffer, 0, offset);
}
}
if (packetData != null && offset >= frameEnd)
{
// frame acquired
Array.Copy(buffer, frameStart, packetData, 0, packetData.Length);
_videoPacketAcquired(packet);
// clean up acquired frame
packetData = null;
offset -= frameEnd;
Array.Copy(buffer, frameEnd, buffer, 0, offset);
}
}
}
}
