Error recovery for Packet Audio and Video
-
Upload
stephanie-rokos -
Category
Documents
-
view
34 -
download
0
description
Transcript of Error recovery for Packet Audio and Video
![Page 1: Error recovery for Packet Audio and Video](https://reader036.fdocuments.net/reader036/viewer/2022082405/5681305d550346895d9626c4/html5/thumbnails/1.jpg)
Error recovery for Packet Audio and Video
Henning SchulzrinneColumbia UniversityNew York, NY
![Page 2: Error recovery for Packet Audio and Video](https://reader036.fdocuments.net/reader036/viewer/2022082405/5681305d550346895d9626c4/html5/thumbnails/2.jpg)
Options for reliability
retransmissionredundancyinterleavingforward error correction
![Page 3: Error recovery for Packet Audio and Video](https://reader036.fdocuments.net/reader036/viewer/2022082405/5681305d550346895d9626c4/html5/thumbnails/3.jpg)
Redundancy
packet
redundant coding offset in timebut: lose coding state
hi-bw content
(e.g. MPEG audio) lo-bwcontent
RTP packet header
![Page 4: Error recovery for Packet Audio and Video](https://reader036.fdocuments.net/reader036/viewer/2022082405/5681305d550346895d9626c4/html5/thumbnails/4.jpg)
Retransmission
receiver requests missing packets by sequence number
scalable multicast under developmentused by RTP H.261 codecusually, delay too highuseful for passive listeners, recording
devices
![Page 5: Error recovery for Packet Audio and Video](https://reader036.fdocuments.net/reader036/viewer/2022082405/5681305d550346895d9626c4/html5/thumbnails/5.jpg)
Forward Error Correction
exclusive OR (XOR) or Reed-SolomonN > 1 redundant packets within blockXOR: parity of other packets in blockcan recover if <= N lostXOR: low complexitymedia independentgreat for multicast
![Page 6: Error recovery for Packet Audio and Video](https://reader036.fdocuments.net/reader036/viewer/2022082405/5681305d550346895d9626c4/html5/thumbnails/6.jpg)
Interleaving
typically, several frames per packet (header overhead!)
split samples or frames across packets
packet loss affects smaller amount of voice data
increases delay, header overhead