Real-time video streaming performance: DMA (Linux) kernel buffer - PDF document

CS 503 Park Real-time video streaming performance: DMA (Linux) → kernel buffer queueing dynamics − Isochronous DV FireWire over Linux: Kernel Buffer Size 4.5e+06 4e+06 kernel buffer size (bytes) 3.5e+06 3e+06 2.5e+06 2e+06 1.5e+06 1e+06 500000 0 0 10000 20000 30000 40000 50000 60000 time (msec)

CS 503 Park User-perceived quality: hit-miss rate → even on sender-side − Isochronous DV FireWire over Linux: Miss vs. Hit miss hit 0 500 1000 1500 2000 frame index

CS 503 Park Causality: why? → variable rate video compression − Size of H.261-encoded Video Frames 40000 encoded frame size (bytes) 35000 30000 25000 20000 15000 10000 5000 0 0 500 1000 1500 2000 frame index

CS 503 Park What about Windows XP? → same set-up (hardware, application, workload − → much worse − Isochronous DV FireWire over Windows: Miss vs. Hit miss hit 0 500 1000 1500 2000 frame index

CS 503 Park Achieved frame rate: Windows XP desktop videoconfer- encing apps → AOL, MSN, Skype, Yahoo − Comparison of Instantaneous Frame Rate Skype 30 MSN Yahoo 25 AOL frames rate (fps) 20 15 10 5 0 0 10 20 30 40 50 60 time (sec)