Despite the increasing popularity, Internet video streaming to mobile devices is still challenging. In particular, there has been a format and resolution "gap" between Internet videos and mobile devices, so mobile users have high demand on video transcoding to facilitate their specific devices. However, as a computation-intensive work, video transcoding is greatly challenged by the limited battery capacity of mobile devices. In this paper we propose and implement "Cloud Transcoder", which utilizes an intermediate cloud platform to bridge the "gap" via its special and practical designs. Specifically, Cloud Transcoder only requires the user to upload a video request rather than the video content. After getting the video request, Cloud Transcoder downloads the original video from the Internet, transcodes it on the user's demand, and transfers the transcoded video back to the user with a high data rate via the intra-cloud data transfer acceleration. Therefore, the mobile device only consumes energy in the last step - fast retrieving the transcoded video from the cloud. Running logs of our real-deployed system confirm the efficacy of Cloud Transcoder.