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)
{
offset += stream.Read(buffer, offset, NetworkStreamReadSize);
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 = 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);
}
Thread.Sleep(10);
}
}
}
/// <summary>
/// 获取视频数据线程
/// </summary>
/// <param name="token"></param>
/// <returns></returns>
protected override unsafe void Loop(CancellationToken token)
{
//创建tcp连接
using (var tcpClient = new TcpClient(_configuration.DroneHostname, VideoPort))
//获取网络流
using (NetworkStream stream = tcpClient.GetStream())
{
var packet = new VideoPacket();
byte[] packetData = null;
int offset = 0;
int frameStart = 0;
int frameEnd = 0;
//由缓存大小建立数组
var buffer = new byte[FrameBufferSize];
//只用指针
//防止地址改变
fixed(byte *pBuffer = &buffer[0])
//循环获取视频数据
while (token.IsCancellationRequested == false)
{
//判断是否可用
if (tcpClient.Available == 0)
{
Thread.Sleep(1);
continue;
}
//从流中读取数据 读入buffer
int read = stream.Read(buffer, offset, NetworkStreamReadSize);
//无数据继续读取
if (read == 0)
{
continue;
}
//重新设置读取位置
offset += read;
if (packetData == null)
{
// lookup for a frame start
//设置数据的最大检索范围。要减去parrot_video_encapsulation_t的大小
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
//拷贝视频数据
Array.Copy(buffer, frameStart, packetData, 0, packetData.Length);
//发送视频获取信息
_videoPacketAcquired(packet);
// clean up acquired frame
packetData = null;
offset -= frameEnd;
Array.Copy(buffer, frameEnd, buffer, 0, offset);
}
}
}
}
