feed

A feed is an actual media stream. A file container can contain a single or multiple feeds.

While contained in a <track>, a feed corresponds to a specific <version>. A version can be either a creative iteration or different qualities and resolutions for the parent <track>.

The vuid attribute indicates the version of the <feed>.

Within a <track>, each <feed> has a different vuid.
Across multiple <track> elements, any <feed> with matching vuid constitutes a version.

<span> elements within a <feed> must all contain the same type of media, as defined by the media handler used by the Gateway.

Attributes

Attribute	Data Type	Allowed Values	Occurrence	Description
type	string	`feed`	0-1	Type of the element.
version	unsigned integer	`7`	0-1	Version of the XML element.
uid	string	any	1	Uniquely identifies the feed. This ID is usually universally unique but needs to be at least unique within the clip.
vuid	string	any	1	Identifies the version of the feed. In a `<track>` element, no two `<feed>` elements can have the same `vuid`. `<feed>` elements in different `<track>` elements can share the same `vuid`.

Note: Optional attributes (0 occurrence attributes) will be inferred from the parent node.

Children

Element	Data Type	Occurrence	Description
`<storageFormat>`	dict	0-1	Describes the format of the media referenced. This element is populated by the Gateway and is generally not required when creating an Open Clip.
`<spans>`	spans	0-1	List of `<span>` representing media files to read on disk.
`<handler>`	handler	0-1	Feed's handler information.
`<sampleRate>`	rate	0-1	Sample (frame) rate of the feed. If not defined, feed timing is frame-based.
`<startTimecode>`	time	0-1	Start timecode of the feed. If not defined, the start timecode of the first `<span>` in `<spans>` will be used.
`<startOffset>`	64-bit integer	0-1	The offset represents the difference between the used index when accessing the parent `<track>` and the actual sample index used to query the spans.
`<duration>`	time	0-1	The duration of the feed. The sum of the duration of all the `<span>` in `<spans>` if not specified.
`<comment>`	string	0-1	Unparsed text converted into a clip note.
`<userData>`	dict	0-1	Dictionary of metadata that is passed through without interpretation.

Note: Child elements with the attribute computed=1 will be ignored when parsed.

Examples

Example 1

The simplest feed object can only point to the media it references.

<feed vuid="v0" uid="f0">
    <spans>
        <span>
            <path encoding="file">Media/Video1.mov</path>
        </span>
    </spans>
</feed>

Example 2

Any additional elements added override the media metadata or add metadata to the media without changing its header.

<feed vuid="v0" uid="f0">
    <comment>My comment</comment>
    <spans>
        <span>
            <path encoding="file">Media/Video1.mov</path>
        </span>
    </spans>
</feed>

Example 3

Feed start timecode and duration can be modified to enforce specific timing, ignoring the media's actual duration. This example creates a feed longer than the existing media. Gaps where no media exist are padded with No Media content.

<feed vuid="v0" uid="f0">
    <startTimecode type="time">
        <nbTicks>86400</nbTicks>
        <rate type="rate">24</rate>
    </startTimecode>
    <duration type="time">
        <nbTicks>8640</nbTicks>
        <rate type="rate">24</rate>
    </duration>
    <sampleRate>24</sampleRate>
    <spans>
        <span>
            <path encoding="file">Media/Video1.[1000-2000].dpx</path>
        </span>
    </spans>
</feed>

Example 4

Here is an example with a feed having two spans of four frames and a start offset of -2.

Feed indexes   [00--01--02--03--04--05--06--07--08--09--10]
Spans indexes  ########[00--01--02--03][00--01--02--03]####

<feed vuid="v0" uid="f0">
    <startOffset>-2</startOffset>
    <spans>
        <span>
            <path encoding="file">Media/Video1.[00-03].dpx</path>
            <path encoding="file">Media/Video2.[00-03].dpx</path>
        </span>
    </spans>
</feed>

Example 5

Here is an example with a feed having two spans of four frames and a start offset of 2.

Feed indexes   ########[00--01--02--03--04--05--06--07--08--09--10]
Spans indexes  [00--01--02--03][00--01--02--03]####################

<feed vuid="v0" uid="f0">
    <startOffset>2</startOffset>
    <spans>
        <span>
            <path encoding="file">Media/Video1.[00-03].dpx</path>
            <path encoding="file">Media/Video2.[00-03].dpx</path>
        </span>
    </spans>
</feed>