public static RTPVP8Header GetVP8Header(byte[] rtpPayload)
{
RTPVP8Header vp8Header = new RTPVP8Header();
int payloadHeaderStartIndex = 1;
// First byte of payload descriptor.
vp8Header.ExtendedControlBitsPresent = ((rtpPayload[0] >> 7) & 0x01) == 1;
vp8Header.StartOfVP8Partition = ((rtpPayload[0] >> 4) & 0x01) == 1;
vp8Header._length = 1;
// Is second byte being used.
if (vp8Header.ExtendedControlBitsPresent)
{
vp8Header.IsPictureIDPresent = ((rtpPayload[1] >> 7) & 0x01) == 1;
vp8Header._length = 2;
payloadHeaderStartIndex = 2;
}
// Is the picture ID being used.
if (vp8Header.IsPictureIDPresent)
{
if (((rtpPayload[2] >> 7) & 0x01) == 1)
{
// The Picure ID is using two bytes.
vp8Header._length = 4;
payloadHeaderStartIndex = 4;
vp8Header.PictureID = BitConverter.ToUInt16(rtpPayload, 2);
}
else
{
// The picture ID is using one byte.
vp8Header.PictureID = rtpPayload[2];
vp8Header._length = 3;
payloadHeaderStartIndex = 3;
}
}
vp8Header._payloadDescriptorLength = payloadHeaderStartIndex;
// Payload header only on first packet in frame.
if (vp8Header.StartOfVP8Partition)
{
byte s0 = (byte)((rtpPayload[payloadHeaderStartIndex] >> 5) & 0x07);
vp8Header.ShowFrame = (byte)((rtpPayload[payloadHeaderStartIndex] >> 4) & 0x01) == 1;
vp8Header.IsKeyFrame = (rtpPayload[payloadHeaderStartIndex] & 0x01) == 0;
byte s1 = rtpPayload[payloadHeaderStartIndex + 1];
byte s2 = rtpPayload[payloadHeaderStartIndex + 2];
vp8Header.FirstPartitionSize = s0 + (8 * s1) + (2048 * s2);
vp8Header._length += 3;
}
return(vp8Header);
}
public byte[] GetFramePayload()
{
List <byte> payload = new List <byte>();
foreach (var rtpPacket in _packets.OrderBy(x => x.Header.SequenceNumber))
{
if (FrameType == FrameTypesEnum.VP8)
{
var vp8Header = RTPVP8Header.GetVP8Header(rtpPacket.Payload);
payload.AddRange(rtpPacket.Payload.Skip(vp8Header.PayloadDescriptorLength));
}
else
{
payload.AddRange(rtpPacket.Payload);
}
}
return(payload.ToArray());
}
