Cloud Transcoding for Mobile Devices

Abstract

Despite its increasing popularity, Internet video streaming to mobile devices confronts many challenging issues. One such issue is the format and resolution gap between Internet videos and mobile devices: many videos available on the Internet are encoded in formats not supported by mobile devices, or in resolutions not best suited for streaming over cellular/WiFi networks. Hence video transcoding for specific devices (and to be streamed over cellular/WiFi networks) is needed. As a computation-intensive task, video transcoding directly on mobile devices is not desirable because of their limited battery capacity. In this chapter, we propose and implement Cloud Transcoder, which utilizes an intermediate cloud platform to bridge the format/resolution gap by performing video transcoding in the cloud. Specifically, Cloud Transcoder only requires the user to upload a video request (i.e., a URL link to the video available on the public Internet as well as the user-specified transcoding parameters) rather than the video content. After receiving the video request, Cloud Transcoder downloads the original video from the Internet, transcodes it on the user’s demand, and delivers the transcoded video back to the user. Therefore, the mobile device only consumes energy during the last step—but generally with much less energy consumption than downloading the original video from the Internet, due to faster delivery of transcoded video from the cloud platform. Running logs of our real-deployed system validate the efficacy of Cloud Transcoder.