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MPEG-4 on IP Framework draft-singer-mpeg4-ip-00 MPEG M6150

MPEG-4 on IP Framework draft-singer-mpeg4-ip-00 MPEG M6150. Joint IETF/MPEG submission, IETF to ‘standardize’ David Singer singer@apple.com Apple Computer, USA. Why? and What?. Common framework for ANY part, or all, of MPEG-4 agree on that which can be agreed on…

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MPEG-4 on IP Framework draft-singer-mpeg4-ip-00 MPEG M6150

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  1. MPEG-4 on IP Frameworkdraft-singer-mpeg4-ip-00MPEG M6150 Joint IETF/MPEG submission, IETF to ‘standardize’ David Singer singer@apple.com Apple Computer, USA

  2. Why? and What? • Common framework for ANY part, or all, of MPEG-4 • agree on that which can be agreed on… • intended to be non-controversial • collation of ideas and practices • Enhance interoperability • Document and assign MIME types • Refer to and use only existing drafts and specifications MPEG-4 on IP

  3. Areas Covered • Use of RTP • common features of payload formats • Unicast and Multicast • Use of SDP • Use of RTSP • MIME names for MPEG-4 files and data structures MPEG-4 on IP

  4. Areas NOT covered • RTP payload formats (there are several already) • Or their names (RTPMAP names) MPEG-4 on IP

  5. RTP mapping • Send in decode order • 1st frame in each packet, allow interleave • Timescales the same • Timestamp is the presentation time (Composition time stamp) • Use RTP synchronization (map OCR or FCR to NTP) MPEG-4 on IP

  6. RTP payload formats • One, simple, base-level scheme ought to be available • carry any Mpeg-4 stream • possibly non-optimally • any receiver ought to be able to handle it • it’s good if senders can be persuaded to send it • One scheme only for Flexmux • handles the many-small-PDUs problem MPEG-4 on IP

  7. RTP Payloads needed • Encourage development of new schemes • Media-aware packetization • Error resilience and protection • either use existing and developing IETF techniques • or do custom formats, if more applicable • (combined source/channel coding) MPEG-4 on IP

  8. SDP Use—IOD • 0 or 1 MPEG session in an SDP session • would be good to loosen this restriction • If an IOD is needed, find by • URL giving location • or DESCRIBE in RTSP, if no location given • global attribute a=mpeg4-iod[:location] • two round trips, different ‘accept’ values, in SDP • location is data:, http: etc. MPEG-4 on IP

  9. SDP Use—Stream Mapping • Mapping Elementary Stream IDs (MPEG) to RTP session • single stream • FlexMux • For single streams, attrribute a=mpeg4-esid <a> • For flexmux, part of • a=mpeg4-flexmuxinfo:locatioon MPEG-4 on IP

  10. RTSP Usage • Care with sessions, which are dependent/independent streams • Care with tearing down streams and losing session ID • Dual round-trip IF IOD is needed noted already MPEG-4 on IP

  11. MIME names • The MPEG-4 format when used as a file (e.g. HTTP) • The IOD, over RTSP/DESCRIBE or file access • FlexMux Info (mapping, structure) • Not payload names for RTPMAP • they are in the I-Ds or RFCs that document those payload formats MPEG-4 on IP

  12. Issues • MIME name for the standard file format: • MPEG4 or MP4? • Video, audio, or application? • Indicating terminal buffering needed? • At most 1 MPEG session in SDP • (Ignorance)? • file format for elementary streams • Multicast URLs • Flexmux tables? MPEG-4 on IP

  13. Next steps • (MPEG has reviewed once) • Form next draft based on IETF and MPEG comments • probably also email discussion • AHG meeting in September • MPEG meeting in October MPEG-4 on IP

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