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C.P0055 PSVT Joint Meeting of WG3 and SWG1.2

C.P0055 PSVT Joint Meeting of WG3 and SWG1.2. Problem Statement. V ideo codecs used in 3GPP 2 are flexible and designed to be leveraged across multiple applications and multiple networks

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C.P0055 PSVT Joint Meeting of WG3 and SWG1.2

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  1. C.P0055 PSVTJoint Meeting of WG3 and SWG1.2

  2. Problem Statement • Video codecs used in 3GPP2 are flexible and designed to be leveraged across multiple applications and multiple networks • IETF protocols (e.g. RTP, RTCP, SDP and SIP) are also generic and developed to be leveraged across multiple services and multiple networks • For 3GPP2 Packet Switched Video Telephony, • What are the optimal settings for codecs and protocols? • What is the impact on the user experience?

  3. Impact on User Experience • Performance degradation due to packet losses • Packetization choices and reduction in available bandwidth • Impact of RTCP on media payload bandwidth • Timeliness of RTCP feedback • Error mitigation solutions • encoder based • transport based • decoder based • Latency issues • etc.

  4. Video / Audio Codec Video / Audio Codec RTP Packet Loss S / W RTP RTP UDP UDP IP IP cdma2000 / WCDMA cdma2000 / WCDMA MS Bitrate MS or Content Server MAC-PDU Sizes Error Masks Effect of Packet Losses? • RTP-level error insertion software tool • Maps MAC-PDU loss traces to SDU losses seen by the decoder

  5. Example: Foreman • SCH 8x in RC3 (MAC-PDU size = 160 octets) • Channel = Model A (Ped 3km/h) • FER = 1%; Active set = 1; Geometry = 6dB

  6. What do we measure? • Objective metric: PSNR averaged over the session • Usage is similar to that as MOS for vocoders • Not informative for video in error prone conditions • New Objective Video Quality metrics under development • Percentage Degraded Video Duration (pDVD) • Standard deviation of PSNR (STD_PSNR) over the session • In addition to average PSNR • Motivation: Objective metrics correlate well with user experience

  7. Potential Gains : Foreman Example • Timely feedback is used in this example and compared with regular Intra-refresh (FER=3%) • Last two rows compare RTT of 200 ms and 500 ms, respectively

  8. Potential Gains : Foreman Example

  9. Common Conditions • Video Source • C12-20051012-006, “Video Database for 3GPP2 multimedia services”, Apple Computer and Qualcomm Inc. • Test Conditions • C12-20051024-004, “Test Conditions for Video Codec Performance in PSVT”, Qualcomm Inc. • Proposed Bearers for PSVT (C12-20051024-004) • SET-1 : • Average bitrate: Conversational Interactive Video 32k (ProfileID = 0x0301) • Maximum bitrate: Conversational Interactive Video 48k (ProfileID = 0x0303) • SET-2 : • Average bitrate: Conversational Interactive Video 40k (ProfileID = 0x0302) • Maximum bitrate: Conversational Interactive Video 56k (ProfileID = 0x0304) • Set-3 : • Average bitrate: Conversational Interactive Video 24k (ProfileID = 0x0300) • Maximum bitrate: Conversational Interactive Video 64k (ProfileID = 0x0305)

  10. What we need from WG-3 • Reverse link and Forward link error-delay traces for the 3 sets • Typical loading conditions • Low, Medium and Full • Typical range of FER conditions (at MAC-PDU level) • 0.5, 1 and 2% • Typical geometries • The above will be included in the TR “Simulation Methodology for Multimedia Services”, C00-20051205-037R2

  11. Assumptions • Typical forward link scheduling algorithm • Adequate information to enable cross-validation • For video streams, packet loss rate is a dominant factor affecting user experience • Impact of random placement of I-frames on packet delivery times (due to Scheduler on the forward link) • do not significantly affect “delay distribution profiles” • small differences in distribution profiles do not have significant effect on the user experience in VT • can be ignored in the generation of error-delay profiles for video streams • Jitter and Packet losses in the core network are negligible, compared with those on the air interface • The MAC-level error-delay profiles can be post-processed to include core network effects in future

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