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Amazon Web Services has launched a beta of a new Web service that can execute in the cloud the heavy data-crunching job of transcoding video.

The Amazon Elastic Transcoder converts high-fidelity video files into smaller-size formats more suitable for viewing on the Web and mobile phones.

The process of transcribing video can be an ornery task, AWS explained in an introductory Web page to the service. Transcoding software can be cumbersome to deploy and configure, and it is difficult to scale.

Users also have to provision servers to transcode the video. Transcoding can be computationally intensive. The process usually involves copying the video into an uncompressed raw format and then copying it again into the new format.

The AWS service aims to simplify the transcoding process as much as possible. Users can set up jobs through a dedicated console or by way of APIs (application programming interfaces). The company offers a number of preconfigured settings, some of which tailor the video specifically for the Apple iPhone 4.

For input, the Transcoder can ingest video files in the 3GP, AAC, AVI, FLV, MP4 and MPEG-2 formats, and emit the same footage in compressed H.264, Apple AAC or MP4 formats.

Not all formats supported

The service does not, however, support either the open-source Ogg video – supported by the Firefox browser – or Google's WebM format. "We asked customers which format they are most interested in transcoding to and the majority wanted H.264/AAC/MP4," an FAQ for the service stated.

To run the service, the user places a video in one AWS S3 (Simple Storage Service) bucket, sets up a workflow using the transcoder, specifies the output format or uses a preset and then retrieves the output file in another S3 bucket. The time it takes AWS to transcode video depends on a number of factors, such as input file size, resolution and bitrate, as well as the user's backlog. A 10 minute video for the iPhone 4, for instance, might take about 10 minutes to transcode. Users are limited to four transcoding pipelines, 50 presets and 1,000 active transcoding jobs at any given time.

AWS offers 20 minutes of free video conversion each month. After that, users will be charged based on resolution, the length of video copied and the user's location. For customers in the Eastern U.S., for instance, encoding standard definition video will cost US$0.015 per minute of footage and high-definition encoding (720p and above) will cost $0.030 per minute.

AWS is not alone in offering transcoding as a Web service. Last week, Microsoft introduced an Azure-based video delivery service that included transcoding functions as well.