Transcript Power Consumption of Google Android`s Video Decoder
School of Computing Science Simon Fraser University Power Consumption of Google Android’s Video Decoder Mathieu Spénard
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Outline
Goal
How the experiment was conducted
Experiment results
Challenges and Difficulties
Conclusion Mathieu Spénard 2
Goal
Understand how a video decoder consumes power within a cell phone, when renderin H.264/AVC encoded videos
Experiment done on a real phone, not a chip
Understand how various processes involved in a phone impacts the overall power consumption of rendering a video Mathieu Spénard 3
Tools Used
Power Tutor [1], which allows measuring power on the phone using a software with a 5% accuracy for the HTC G1, HTC G2 and Nexus One
Ffmpeg [2] to encode videos
City, Crew and Foreman video sequences [3]
Linda File Manager [4], a free file management system that allows for quickly navigating files within an Android phone Mathieu Spénard 4
Experiment
Encoded City, Crew and Foreman using ffmpeg
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30fps
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CIF
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Bitrates from 100kbps to 3000kpbs
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Noted the mean Y-PSNR
Transfer the files to a Google Nexus One phone Set it to plane mode (no 3G antenna/WiFi) Start PowerTutor Using Linda Manager, navigate and start an encoded video When it is over, stop PowerTutor, save the log and rename it so it is easy to retrieve
Repeat for all encoded videos Mathieu Spénard 5
Results
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Results
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Results
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Results
Video decoder couldn’t play videos encoded at 2000, 2250 and 2500 kbps, and also from 4000 to 5000 kbps
Couldn’t stop the Compass process. Consumes very little power, but could add to the operating system overhead Mathieu Spénard 9
Challenges and Difficulties
Was not parsing the right data at the beginning
PowerTutor is slow
PowerTutor has a too coarse granularity
Not a lot of precision for the OLED screen power consumption because of an unrooted phone (brightness only) Mathieu Spénard 10
Conclusion
Bitrate and mean Y-PSNR do have an impact on the power consumption of a H.264/AVC video decoder
System overhead consumes more power than decoding
Screen consumes most of power; does not leave a lot of room for improvement
A study using a 3D video decoder could give a different decoder/screen power consumption Mathieu Spénard 11
References
[1] “PowerTutor,” http://ziyang.eecs.umich.edu/projects/powertutor/
[2] “FFmpeg.” [Online]. Available: http://www.ffmpeg.org/
[3] “Video Library and Tools - NSL.” [Online]. Available: http://nsl.cs.sfu.ca/wiki/index.php/Video_Library_and_ Tools
[4] “Linda File Manager.” [Online].Available: http://www.androlib.com/android.application.com/lind aandny-lindamanager-jpBj.aspx
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