The following is a precise subset of Timed Text XML tags supported by the FLVPlaybackCaptioning component.

tt tag - Top level tag

All attributes of tt tag are ignored.

The metadata tag is allowed, but ignored at any level of the document.

The set tag is allowed, but ignored at any level of the document.

The following time values are supported:

• full clock format

  (e.g. 00:03:00.1)

• partial clock format

  (e.g. 03:00.1)

• offset time

  (e.g. 100.1s or 20h)Offset times without units (for example, 10) are assumed to be seconds.

  • There is no support for any time format that includes frames or ticks (for example: 00:03:00:05, 00:03:00:05.1, 30f, 30t).

  • begin, dur and end are allowed in p tag only, therefore, all times given are relative to the media.

xml:lang attributes are ignored.

xml:space attributes are ignored, the FLVPlaybackCaptioning component assumes xml:space=default.

The head tag is optional, use one or none.

• styling tag requires an id attribute; support for one or more style tags inside.

  • Supported attributes:

    • tts:backgroundColor

      The entire text area has the same background color. You can set it at any supported tag level, but it will affect every paragraph, span, and so on in the currently visible captioning text.

      Support for all legal color representations, however, the alpha component is ignored unless set to 0. If alpha is 0, no background color is displayed. A value of transparent is treated as alpha 0.

    • tts:color

      Support for all legal color representations, however, the alpha component is ignored. A value of transparent is treated as black.

    • tts:fontFamily

    • tts:fontSize

      Support for the first (vertical) value only (if two fontSize attributes exist). Units are optional (assumed to be in pixels). Support for absolute (for example, 12) and relative (for example +2). Percentage values are not supported.

    • tts:fontWeight

    • tts:textAlign

    • tts:wrapOption

      The wrapOption attribute applies to the entire text area (for example, every paragraph, span, and so on that is currently visible.

  • Unsupported attributes:

    • tts:direction

    • tts:display

    • tts:displayAlign

    • tts:dynamicFlow

    • tts:opacity

    • tts:origin

    • tts:overflow

    • tts:padding

    • tts:showBackground

    • tts:textOutline

    • tts:unicodeBidi

    • tts:visibility

    • tts:writingMode

    • tts:zIndex

The layout tag is ignored, including any region tags included therein.

The body tag is required; only one body tag is permitted.

• The body tag supports the attributes style, and any style attributes.

• The attributes begin, dur, end, id, region, timeContainer and any others are ignored in the div tag.

• Support for zero or more p tags

  • Support for the attributes begin, dur, end, style and any style attributes in the p tag.

  • The attributes id, region, timeContainer and any others are ignored in the p tag.

  • The attribute begin is required. If the begin attribute is omitted, a silent failure occurs.

  • If there is no dur or end attribute, then the caption is dismissed by the next caption.

  • If both dur and end attributes are encountered, then the end attribute is used.

  • The p tag supports a mix of span tags, br tags and text (per the W3C specification).

  • The metadata and set tags are allowed, but ignored.

  • The span tag

    -No support for nexted spans.

    -Support for attribute style and any style attributes in the span tag.

    -The attributes begin, dur, end, id, region, timeContainer and any others are ignored in the span tag.

  • br tag. All attributes and contents of a br tag are ignored.

When the FLVPlaybackCaptioning component parses the Timed Text XML file, the begin captioning timing information is transformed into ActionScript cue points, which are added to the FLVPlayback instance’s list. The cue points use the naming convention that begins with the prefix "fl.video.caption2.0." Do not create any cue points with these prefix names unless you want them to be used for captioning.

© 2011 Adobe Systems Incorporated. All rights reserved.
Mon Nov 28 2011, 07:50 AM -08:00