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Affiliation 1) Eindhoven University of Technology Department of Mathematics and Computer Science

I. B. B. P. B. B. P. B. B. (. I. ). 0. 1. 2. 3. 4. 5. 6. 7. 8. 9. IFD – a technique for improving the quality of wireless video streaming Author: S. Kozlov 1 . Co-authors: Peter v.d. Stok 1,2 , Johan Lukkien 1. 1. Introduction

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Affiliation 1) Eindhoven University of Technology Department of Mathematics and Computer Science

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  1. I B B P B B P B B ( I ) 0 1 2 3 4 5 6 7 8 9 IFD – a technique for improving the quality of wireless video streamingAuthor: S. Kozlov 1. Co-authors: Peter v.d. Stok 1,2, Johan Lukkien 1 1. Introduction A crucial point in using wireless networks for multimedia tasks is the effective use of highly fluctuating network resources. Using the sender buffer as instant indicator of the varying network state, we implement a simple yet effective technique to greatly improve the quality of video streaming over wireless link. 3. IFD (I Frame Delay) scheduler waiting (buffered) frame sent frame incoming frame C W S WHILE (TRUE) DO WHILE (C is empty) DO Nothing IF (W is empty) THEN Store C in W ELSE IF (C is of type I) THEN Overwrite W with C ELSE IF (C is of type B) Discard C ELSE IF (W is of type I or P) Discard C ELSE Overwrite W with C 2. MPEG over wireless link Bandwidth variations Buffer occupancy: • Link: 802.11b • UDP effective throughput • Discretisation time: 40ms • Microwave oven on: between 5 and 13 seconds Video: 4Mbps, bandwidth: 1.6Mbps Video: 4Mbps, bandwidth: 2.5Mbps Sender’s buffer 4. Testing and validation Physical and link layers (802.11) Layers above link layer • Stream: 1min, 25fps, 3 various bit-rates • Link: 802.11b • Microwave oven on: between 20s and 40s Packets get lost here Socket buffer Bandwidth variations may cause the buffer to overflow Video bit-rate: 4Mbps. Losing B frames mostly when the oven is on Quality degradation Frame inter-dependencies: losing a P frames (red cross) causes the dependent frames to be decoded incorrectly (grey crosses) Video bit-rate: 8Mbps. Also I and P frames get lost when the oven is on Video bit-rate: 5Mbps. No I or P frames get lost Losing an I or P frame: • 5. Conclusions • Simple (only the sender should be changed) • Cost effective (small buffers needed) • Works with any terminals supporting RTP reception and equipped with a general MPEG decoder • Very reactive against fast network fluctuations • Very small buffer (2 frames) -> low latency (80ms) • Tolerating bandwidth degradation of up to 50% of the video bit-rate Cumulative weight of B frames is more than 50% Affiliation 1) Eindhoven University of Technology Department of Mathematics and Computer Science HG 6.57, P.O. Box 513, NL-5600 MB, Eindhoven, The Netherlands 2) Philips Research NatLab Prof. Holstlaan 4, 5656AA Eindhoven, The Netherlands

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