1 / 19

Optimal Rate Control for Multiplexed Video Sequences Using MINAVE and MINVAR Approaches

This paper presents an optimal rate controller for multiplexed video sequences, focusing on video transmission over limited bandwidth channels. We explore two criteria, MINAVE and MINVAR, to optimize bandwidth allocation among multiple video streams. We demonstrate the formulation of these problems in the ρ-domain, providing closed-form solutions and simulations comparing both approaches. Our results indicate a minimal coding efficiency loss of 0.5 dB for MINVAR compared to MINAVE. Future work will expand this approach to scalable video coding.

yoland
Télécharger la présentation

Optimal Rate Control for Multiplexed Video Sequences Using MINAVE and MINVAR Approaches

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A -domain Rate Controller for Multiplexed Video Sequences G. Valenzise*, M. Tagliasacchi*, S. Tubaro*, L. Piccarreta *Dipartimento di Elettronica e Informazione, Politecnico di Milano Picture Coding Symposium 2007 November 7-9, 2007 – Lisboa, Portugal

  2. Multiplexing of video sequences • Transmitmultiple video streamsover a sharedchannel • Broadcast television • Video-surveillance • etc… • The channelbandwidthislimited • Equalbandwidthpartitioningisnotoptimal

  3. Optimal multiplexing quality quality time MINAVE Minimize the output averagedistortion MINVAR Minimize the output distortionvariance time quality time • Findanoptimal way to allocate channelbandwidthamongsequences • Example: two video sequences

  4. Agenda • Formulate the MINAVE and MINVAR problems in the -domain • Assumptions: • Constant bit rate (CBR) channel • Frame-by-frameoptimization • Find a closedformsolutionfor the MINVAR • Compare the MINAVE and MINVAR criteria • Check the codingefficiency loss for the averagedistortion • Relax the CBR assumption • Temporalsmoothing

  5. Problem formulation Rate-distortion operational curve of each frame can be described in the ρ-domain (He and Mitra, 2002): ρ-domain parameters can be estimated from decoded sequences

  6. Problem formulation - MINAVE (He and Mitra, 2002)

  7. Problem formulation - MINVAR Which is equivalent to solving When

  8. MINAVE vs. MINVAR (simulation) MINAVE MINVAR

  9. MINAVE vs. MINVAR • AveragedistortionofMINAVE • AveragedistortionofMINVAR • Weknow (bydefinition!) • QUESTION: • Whatis the codingefficiencyloss?

  10. MINAVE vs. MINVAR: averagedistortionsurface MINVAR (suboptimal) Global Optimum (MINAVE)

  11. CodingEfficiency Loss • Averagedistortionof MINAVE • Averagedistortionof MINVAR • The codingefficiency loss is

  12. Simulations: CodingEfficiency Loss

  13. TemporalSmoothing • Relax the CBR assumption • Introduce a shared encoder buffer toperform VBR encoding • Weapply the MINVAR rate allocationwhile at the sametimeachievingtemporalsmoothing • Foreachtimeinstant: • Compute the CBR distortionprofile • Smoothitwith the low-passfilter (He, Zen and Chen, 2005) • Set Dsmoothas the target distortion and computeratesRi • Relax or tighten the rate constraintaccordingto the current buffer level

  14. Temporal smoothness

  15. Experiment: transcoding Rate controller H.264 bitstream H.264 decoder H.264 encoder BUFFER H.264 decoder H.264 encoder H.264 bitstream ... H.264 decoder H.264 encoder H.264 bitstream

  16. H.264/AVC results MINAVE MINVAR smoothed MINVAR

  17. H.264/AVC results MINAVE MINVAR smoothedMINVAR

  18. Conclusions • Summary: • Proposed a MINVAR bit allocationformultiplexed video sequences • The MINVAR allocationleverages on the -domain model (butworks on anyexponentialmodel, i.e. at high rates) • The codingefficiency loss w.r.t. MINAVE is, on average, of 0.5 dB • Future work: • Apply the MINVAR approachtoScalable Video Coding solve a discreteoptimizationproblem…

  19. Thankyou! Questions?

More Related