Avalon Media System
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Comment: Added Transcoding API

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The Transcoding API will consist of a set of lightweight Ruby classes that will be able to initiate transcoding jobs, distribute derivative files, track/poll job status, and perform common maintenance tasks such as prioritization, cancellation, and cleanup.

Definitions

ConsumerApplication code that makes use of the Transcoding API.
Implementation

The set of classes and methods that make a given Transcoder available to a Consumer via the methods defined in the Transcoding API

JobA single piece of transcoding work
Transcoder

An implementation-specific provider of transcoding services. Examples include OpenCast Matterhorn, Kaltura, Zencoder, and Amazon Elastic Transcoder.

Transcoding APIThe set of classes and methods that can be used to initiate, track and manipulate trancoding jobs.

Classes

Transcoder::Base

An abstract model that serves as the reference for an Implementation.

Class Methods

create(input, output, opts={})

Begin a transcoding operation. Returns a job.

 

find(job_id)

Load and return a single job.

 

find_by_status(*states)

Find all jobs currently in the given state(s).

Instance attributes

  • job_id
  • state
  • current_operations
  • errors
  • original_filename
  • tech_metadata

Instance Methods

  • cancel!
  • canceled?
  • complete?
  • purge!
  • running?
  • update!

Chris's F2F Notes

File submission

  • Select (or use default?) preset/settings
  • Generate MediaObject ID
  • Save MediaObject

...

Process (transcode)

Create job

  Submit

  • File Input file (URL?)
  • Destination Output destination (URL?)
  • Encoding options

  Return

...

  • Status
  • %
  • URL
  • Technical metadata

Failed (Details)

  Submit

  • DetailsJob ID

  Return

  • Status
  • %
  • Error messages
  • Current operations?

...

Depend on encoder/encoder shim to transfer derivatives to streaming server/location

Chris's LCDX Notes

Basic Requirements for local encoding service

  • Start encoding job

  • status of encoding job

    • succeed/failed/canceled

    • current operation (could be hash due to parallelization of derivative creation)

    • errors

    • process complete

  • further in depth details of encoding job (media info report)

    • techMD (aspect ratio, framesize, bitrate)

    • derivatives created (id, url/label, hash)

    • id

    • original filename


Proposed Operation


Shared code, API layer for work.  Run by institution.  Avalon wants local FFMPEG queue based solution.  


  1. Submit job, ID is returned

  2. Use ID for status query

  3. Derivatives placed in proper location by service

Other Proposed Features

  1. Cancel job and retract derivatives (time intensive and some services charge per minute)

  2. Need to support priority flagging, not present in some codebases

Avalon

Jobs

Create

Submit

Input file

Output file

Encoder settings

Response

Job ID

Details

Submit

Job ID

Response

Status

Progress %

Current operations

URL

Technical metadata (input file/output files)

Errors

List by Status

Submit

Job ID

Response

Status

Progress %

Current operations

URL

Technical metadata (input file/output files)

Errors

Cancel

Submit

Job ID

Response

Cancellation confirmation

Retract Derivatives

Submit

Job ID

Response

Retraction confirmation

Zencoder

Zencoder uses a 'Job' to transcode media. The Job specifies all settings in a single package.

API versioned by version number, e.g. 'v2'

Each Job, Input and Output is assigned an (independent) ID

Job states include pending, waiting, processing, finished, failed, and cancelled.

Input states include pending, waiting, processing, finished, failed, and cancelled.

Output states include waiting, queued, assigning, processing, finished, failed, cancelled and no input.

Error codes

Jobs

Create

Submit

Input

Encoder settings (optional)

Response

Job ID

Output ID

List

Submit

Response

Job details for each job

Details

Submit

Job ID

Response

Job details

  • Created at
  • Finished at
  • Updated at
  • Submitted at
  • Pass-through
  • Job ID

Input details

  • Input ID
  • Format
  • Framerate
  • Height
  • Width
  • etc.

Output details

  • Output ID
  • Format
  • Framerate
  • Height
  • Width
  • etc.

State

Resubmit

Submit

Response

Cancel

Submit

Response

Finish (a Live Job)

Submit

Response

Job Progress

Submit

Job ID

Response

Job state

Job progress

Input state

Input progress

Output state

Output progress

Notifications

Register for a notification when a job is completed via HTTP POST, email, etc.

Returns:

  • Job ID
  • Status: 'finished', 'failed', 'cancelled'
  • Output label (if applicable)

Amazon Elastic Encoder

Amazon uses a 'Pipeline' (queue) to transcode a 'Job' according to the settings specified in a 'Preset'.

API versioned by date, e.g. '2012-09-25'

The value of Job:Status is one of the following: Submitted, Progressing, Complete, Canceled, or Error.

Errors

Jobs

Create

Submit

Input file

Output file

Preset ID (encoder settings)

Response

Job details

Input settings

Output details

List by Pipeline

Submit

Response

List by Status

Submit

Response

Read

Submit

Job ID

Response

Input details

  • File
  • Frame rate
  • Resolution
  • Aspect ratio
  • Interlaced
  • Container
  • Detected properties (width, height, frame rate, file size, duration)

Output details

  • ID
  • Output file
  • Rotate
  • Preset ID
  • Duration
  • Width
  • Height
  • Frame rate
  • File size
  • Status
  • etc.

Job details

  • User metadata
  • Status
  • Timing (submit, start, finish)

Cancel

Submit

Response

Notifications

Register for a notification when a Job changes state via HTTP, email, etc.

Returns:

  • State: 'PROGRESSING', 'COMPLETED', 'WARNING', 'ERROR'
  • Error code
  • Message
  • Version (API)
  • Job ID
  • Pipeline ID
  • Input