Lecture 5 and 6 notes: Reji Mathew & Jian Zhang NICTA & CSE UNSW COMP9519 Multimedia Systems S2 2009

COMP9519 Multimedia Systems – Lecture 7 – Slide 2 – R. Mathew & J. Zhang System Overview IP UDP RTP Decoder packetize RTP UDP RTCP MPEG-4 File / Encoder MPEG-4 Video Sender Side Issues -Conforming to Network Bandwidth -Adaptive Rate Control -Error Resilience -Packetization strategy Receiver Side Issues -Buffering input data -Error concealment -Inter media synchronization

COMP9519 Multimedia Systems – Lecture 7 – Slide 3 – R. Mathew & J. Zhang SDP v=0 o=NICTA IN IP s=Camera ONE i=Video stream for realtime surveillance u= (Jian Zhang) c=IN IP /2 t=0 0 a=recvonly m=video RTP/AVP 98 a=rtpmap:98 MP4V-ES/90000 a=fmtp:98 profile-level-id=1; config=000001b … a=orient:portrait Version number Originator information (address of machine from which the session was created) Session name Session Information (text description / title for session) URL for more information about the session Contact person (person responsible not necessarily the creator) Connection Details IN (internet) IP4 (IP v4) address (multicast address/TTL) Time Information (ntp time, “0,0” implies permanent session) Session level attribute (operate in receive only mode) Media Announcement (fmt : refers to media format specific information) (e.g. Dynamic payload number) Media attribute (rtp map) / (map RTP dynamic payload number to media format and clock rate) Media attribute (format specific parameters) (info regarding mpeg-4 media, profile, level & initialization data) Media attribute (orientation) (only used in some applications, example – landscape or portrait) increased when a modification is made to the session data. Recommended that an NTP timestamp is used

COMP9519 Multimedia Systems – Lecture 7 – Slide 4 – R. Mathew & J. Zhang RTSP : Describe Method Retrieves the description of a presentation, identified by the request URL, from a server. The DESCRIBE reply-response pair constitutes the media initialization phase of RTSP. C->S: DESCRIBE rtsp://nicta.com/twister RTSP/1.0 CSeq: 1 S->C: RTSP/ OK CSeq: 1 Content-Type: application/sdp Content-Length: 164 v=0 o= IN IP s=RTSP Session i=An Example of RTSP Session Usage a=control:rtsp:// nicta.com /twister t=0 0 m=audio 0 RTP/AVP 0 a=control:rtsp:// nicta.com /twister/audio m=video 0 RTP/AVP 26 a=control:rtsp:// nicta.com /twister/video Method Presentation URL Version CSeq header field Sequence number for an RTSP request-response pair Must be present in all requests and responses Same CSeq number as request Response line: Version, Status code “200” with description SDP Information (message body) Request line Aggregate control possible (session level control attribute)

COMP9519 Multimedia Systems – Lecture 7 – Slide 5 – R. Mathew & J. Zhang Protocol Stack IP UDP RTP Decoder packetize RTP UDP RTCP MPEG-4 File / Encoder MPEG-4 Video TCP RTSP SDP TCP RTSP SDP