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Basic Media Operations

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This document explores a range of common production operations and the requirements for tracking identity and timing through them. Each granular operation is described and will be referred to in further documents.

This document is not intended to be an exhaustive set of potential operations. However, for any additional operation this document should be sufficient to provide an indication of how to treat it (in terms of its handling of identity and timing).

The headings below state how identity and timing must change as content is handled by the listed operations. The operations are grouped by the number of Flows which are input to and output from the operation purely for convenience in documenting them. For example, ‘1..*:1 Flow’ indicates a ‘many to one’ operation where multiple input Flows are combined in order to produce one output Flow.

These identity changes should be applied in any cases where a process has the potential to make a change to the content, even if it is not currently doing so. For example, a vision switcher’s output should be identified with its own Source ID, even if it is currently acting as a pass-through for a single input.

No Source or Flow Changes

The following operations result in no change made to the content’s existing identity or timing data. They are however likely to generate one or more new Flow Representations of the same Flow.

0:1 Flow

Input

New Flow ID, New Source ID

The following operations result in the generation of new Time Values in an appropriate Time Context.

1:0 Flow

Output

No New Flow ID, No New Source ID

The following operations transition content into an environment outside of the scope of the identity and timing model.

1:1 Flow

Process

New Flow ID, New Source ID

These operations can be broadly summarised as performing one of the following actions:

The following operations might modify the content’s Time Values and/or associated Time Context. Where applicable this action is described.

New Flow ID, Same Source ID

These operations can be broadly summarised as performing one of the following actions:

The following operations make no changes to the content’s Time Values or Time Context. Time Values must be carried through 1:1 from input to output. One exception to this is described under “Sample Rate Conversion” where the Time Context remains the same, but new (interpolated) Time Values might need to be generated.

1..*:1 Flow

Combine

New Flow ID, New Source ID

In all of the following operations Time Values at each input must match such that they can be carried through to the output consistently. If the Time Values do not match up they must first be brought into line using an appropriate 1:1 operation.

1:1..* Flow

Split

New Flow IDs, New Source IDs

In the following operations the Time Values for each output must match the corresponding Data Object’s Time Value from the input.

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