- 1. , .Net SenderInternetReceiverMultiplexerDemultiplexer Audio
VideoAudioVideoEncoder
EncoderDecoderDecoderMicCameraRenderRender
2. RTCP Real-time Transport Control ProtocolRTP Real-time
Transport Protocol ( ) Net Media Data Internet(audio, video) Frame
? UDP/TCP RTP-PacketRFC 3. , .Net1 UDPInternet 112t 223 t 34455 t
53Delay=tUPD < 250ms okTCP , 4 < 500ms acceptable Jitter
Buffer 4. , . : REDundancy, FEC, NACKNet 1RED1 2 1 32 13 ~1 2 3AMR
ISAC 2 Silk 3FEC1 2 21 2 4 NACK1 23 132 1 2 3lost seqNum 5.
NetRTP/RTCP Sender InternetRTP/RTCP ReceiverJitter
BufferMultiplexerRED/FEC/NACK Demultiplexer (RED/FEC/NACK) Audio
VideoAudio VideoEncoder EncoderDecoder DecoderMic Camera Render
Render 6. . Audio G711, G722- Delay 20-60ms G723.1, G729AB- Bitrate
8-64kbpsSpeexother ITU-Ts G7xx - Sampling rate 8-32kHziLBCAMR (NB,
WB) - VAD/DTXiSAC Speex - PLC (Packet Loss Concealment) Silk, Opus
iLBC- Complexity < 80MHz iSAC- Open sourceSilk, Opus - Patent
free : MP3, AAC, WMA, FLAC 7. . VideoMPEG1/2, H263, MPEG4 H264,
VP8- Encoding qualityH264, VP8Key Frame SideInfo 5xDelta Encoder
MVK0 D1 D2 D3 D4 Quant Delta SmplsK0D1 D2 , , , . 8. RTP: First
Lost Last Frame N Video Deco de Ok. r Ok 9. .Video 75 frames K D DK
D3 sec ( ), - . 10. . Video K D D K DRTCP RTP ( ), - Internet . 11.
. Video -peak-factor K D D R1 D D R2 RTCP , R1 Confirmed(R1) ? R1 :
K R2: Size(R2) ~= Size(K). Internet 12. . Video ( ). K D DK Dslice0
slice1. 13. . Video - (recovery) PLC Packet Loss Concealment 14.
NetRTP/RTCP Sender InternetRTP/RTCP ReceiverJitter
BufferRED/FEC/NACK (RED/FEC/NACK) Audio VideoAudio VideoEncoder
EncoderDecoder DecoderMic Camera Render Render 15. Net RTP/RTCP
Internet RTP/RTCPJitter BufferRED/FEC/NACK (RED/FEC/NACK)
Encoder+PLCRate control Decoder+PLCSilk, iSAC, VP8,Silk,
iSAC,VP8,Speex, H264Windows, OSXSpeex,H264 iOS, Android X86, ARM
AudioProc Mic CameraRender Render Devices 16. ! AEC Acoustic Echo
Canceler 17. AEC - Acoustic Echo Canceler AECInternet mic speaker-
- Double Talk Digital !AnalogAdaptive Digital 18. Net RTP/RTCP
InternetRTP/RTCP RTP/RTCP RTP/RTCP Voice&VideoRED/FEC/NACK
EngineJitter Buffer(RED/FEC/NACK) Encoder+PLC Rate control
Decoder+PLCSilk, iSAC, VP8, Silk, iSAC,VP8,Speex, H264 Windows,
OSXSpeex,H264iOS, Android AECX86, ARM AudioProc Mic Camera Render
RenderDevices 19. Voice&Video Engine 0 : WebRTC, Libjingle,
TODO 20. ! , / [email protected]
