Elastic Transcoder
Amazon Elastic Transcoder is web service that enables you to transcode media files (audio or video) to a particular format, size and quality. This enables you to produce media files for playback on a wide range of devices such as mobiles, tablets, desktop computers and televisions. This article, Amazon Elastic Transcoder – Exam Tips provides a breakdown of important concept you need to understand for the Solutions Architect Associate Exam. The transcoding process involves accepting input files from an S3 bucket, transcoding it and writing the resulting files to another S3 bucket.
Specifically, you have to:
- Create a transcoding pipeline which specifies the input S3 Bucket, the output S3 bucket and the storage class.
- Specify an Identity and Access Management (IAM) role that is used by the service to access your files
- Create a transcoding job by specifying your input files, output file and the transcoding preset to use or specify a custom present if you have created one
You can also receive the status of your transcoding jobs via Amazon Simple Notification Service (SNS) as well as query the status using APIs and via the Console. You can manage the transcoding jobs such as stop, start or cancel.
Amazon Elastic Transcoding services are charged on a per usage model where you only pay for the resources you use. Specifically, you are charged on the following basis:
- Time take to transcode (in minutes)
- Quality (SD or HD)
- Audio Only
Thumbnail generation is free of cost and you can use up to 20 minutes’ audio only, 20 minutes of SD video output and 10 minutes of HD video output per month under the Free Tier service.
4 Core Components
Jobs
You create transcoder jobs to convert media files into specific formats. Each job can convert a single file into a maximum of 30 formats. Specify the name of the file to transcode, the names you want the output files to be given as well as the formats to transcode the files into using Presets (templates that contain settings for common formats). You must first create the pipeline (the queue) that will manage the job.
You can configure Elastic Transcoder to notify you of job status changes such as when Elastic Transcoder starts and finishes processing a job, or for example when it encounters a warning or error condition.
Important Note: you cannot update a job after you have created it and if you need to change settings you have to first cancel it, create a new job based on the one that you cancelled, update the applicable values, and create the new job.
Pipelines
You need to create one or more Pipelines which are essentially queues to help you manage you transcoding jobs. As part of creating Pipelines, you also need to specify the input and output S3 Buckets. Jobs will get processed in a pipeline in the order in which they were added. In addition, if a job is to convert a file into multiple formats, then the order of the output files are created in the order in which you specify the formats.
A simple use case for creating multiple pipelines includes a service which offers a free transcoding vs. paid-for transcoding. In this example, customers opting for a basic free service can get their files transcoded using a standard priority pipeline and customers who opt for the premium paid-for service can get their files placed in the high priority pipeline for when they need the files transcoded immediately.
Additional points to note:
- A pipeline can process multiple jobs simultaneously
- The time required to complete a job depends on file size, the format is converted to and other settings. This means that jobs may not get completed in the order in which it was submitted
- It is possible to pause the pipeline to stop processing jobs. Note if you wish to cancel a job, you should first pause the related pipeline so that Elastic Transcoder does not process the job. This is because once a job is in a progressing state, you cannot cancel it.
Presets
These are templates that contain the most common settings for transcoding media files from one format to another. For example, common formats include templates for iPhone or Android Tablets and iPads.
Custom Presets enable you to create templates to support formats that are not included among the default ones provided. Once you have a preset of your choice, you need to specify it when you create a job to enable Elastic Transcoder to convert the media to the correct format you want. Presets settings enable you to specify audio and video codecs, bit rates and resolution among other settings.
Notifications
You can use Amazon Simple Notification Service (SNS) to deliver notification messages to you for all job status changes. The following are notifications you can configure to be sent to you on job status changes. You can choose to have all notifications or a subset of these to be reported to you:
- Progressing: Elastic Transcoder has started to process a job in the pipeline.
- Completed: Elastic Transcoder has finished processing a job in the pipeline.
- Warning: Elastic Transcoder encountered a warning condition while processing a job in the pipeline.
- Error: Elastic Transcoder encountered an error condition while processing a job in the pipeline.
Finally, when you create pipelines and jobs, they are created in the current region and when creating a new job, you must specify a pipeline that is in the current region. Amazon also recommends that you specify S3 Buckets in the same region as your pipelines and jobs and although you can use S3 buckets located in other regions, you need to be aware of the additional cost involved in data transfer between AWS regions.
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