// todo 3.2 direct opus streams
public int SendPcmFrame(VoiceGateway gw, Span <byte> data, int offset, int count)
{
var secretKey = gw.SecretKey;
if (secretKey.Length == 0)
{
return((int)SendPcmError.SecretKeyUnavailable);
}
// encode using opus
var encodeOutput = _arrayPool.Rent(LibOpusEncoder.MaxData);
try
{
var encodeOutputLength = Encode(data, encodeOutput);
return(SendOpusFrame(gw, encodeOutput, 0, encodeOutputLength));
}
finally
{
_arrayPool.Return(encodeOutput);
}
}
public int SendOpusFrame(VoiceGateway gw, byte[] data, int offset, int count)
{
var secretKey = gw.SecretKey;
if (secretKey is null)
{
return((int)SendPcmError.SecretKeyUnavailable);
}
// form RTP header
var headerLength = 1 // version + flags
+ 1 // payload type
+ 2 // sequence
+ 4 // timestamp
+ 4; // ssrc
var header = new byte[headerLength];
header[0] = 0x80; // version + flags
header[1] = 0x78; // payload type
// get byte values for header data
var seqBytes = BitConverter.GetBytes(gw.Sequence); // 2
var nonceBytes = BitConverter.GetBytes(gw.NonceSequence); // 2
var timestampBytes = BitConverter.GetBytes(gw.Timestamp); // 4
var ssrcBytes = BitConverter.GetBytes(gw.Ssrc); // 4
gw.Timestamp += (uint)FrameSizePerChannel;
gw.Sequence++;
gw.NonceSequence++;
if (BitConverter.IsLittleEndian)
{
Array.Reverse(seqBytes);
Array.Reverse(nonceBytes);
Array.Reverse(timestampBytes);
Array.Reverse(ssrcBytes);
}
// copy headers
Buffer.BlockCopy(seqBytes, 0, header, 2, 2);
Buffer.BlockCopy(timestampBytes, 0, header, 4, 4);
Buffer.BlockCopy(ssrcBytes, 0, header, 8, 4);
//// encryption part
//// create a byte array where to store the encrypted data
//// it has to be inputLength + crypto_secretbox_MACBYTES (constant with value 16)
var encryptedBytes = new byte[count + 16];
//// form nonce with header + 12 empty bytes
//var nonce = new byte[24];
//Buffer.BlockCopy(rtpHeader, 0, nonce, 0, rtpHeader.Length);
var nonce = new byte[4];
Buffer.BlockCopy(seqBytes, 0, nonce, 2, 2);
Sodium.Encrypt(data, 0, count, encryptedBytes, 0, nonce, secretKey);
var rtpDataLength = headerLength + encryptedBytes.Length + nonce.Length;
var rtpData = _arrayPool.Rent(rtpDataLength);
try
{
//copy headers
Buffer.BlockCopy(header, 0, rtpData, 0, header.Length);
//copy audio data
Buffer.BlockCopy(encryptedBytes, 0, rtpData, header.Length, encryptedBytes.Length);
Buffer.BlockCopy(nonce, 0, rtpData, rtpDataLength - 4, 4);
gw.SendRtpData(rtpData, rtpDataLength);
// todo 3.2 When there's a break in the sent data,
// the packet transmission shouldn't simply stop.
// Instead, send five frames of silence (0xF8, 0xFF, 0xFE)
// before stopping to avoid unintended Opus interpolation
// with subsequent transmissions.
return(rtpDataLength);
}
finally
{
_arrayPool.Return(rtpData);
}
}