ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Working with video
Using the StageVideoEvent.RENDER_STATE and VideoEvent.RENDER_STATE events
StageVideo and Video objects send events that inform applications when the display environment changes. These
events are StageVideoEvent.RENDER_STATE and VideoEvent.RENDER_STATE.
A StageVideo or Video object dispatches a render state event when a NetStream object is attached and begins playing.
It also sends this event when the display environment changes; for example, when the video viewport is resized. Use
these notifications to reset your viewport to the current videoHeight and videoWidth values of the event target
object.
Reported render states include:
RENDER_STATUS_UNAVAILABLE
RENDER_STATUS_SOFTWARE
RENDER_STATUS_ACCELERATED
Render states indicate when hardware accelerated decoding is in use, regardless of which class is currently playing
video. Check the StageVideoEvent.status property to learn whether the necessary decoding is available. If this
property is set to “unavailable”, the StageVideo object cannot play the video. This status requires that you immediately
reattach the NetStream object to a Video object. Other statuses inform your application of the current rendering
conditions.
The following table describes the implications of all render status values for StageVideoEvent and VideoEvent objects
in Flash Player:
VideoStatus.ACCELERATED VideoStatus.SOFTWARE VideoStatus.UNAVAILABLE
StageVideoEvent Decoding and presentation
both occur in hardware. (Best
performance.)
VideoEvent Presentation in software,
decoding in hardware.
(Acceptable performance on a
modern desktop system only.
Degraded full-screen
performance.)
Presentation in hardware,
decoding in software.
(Acceptable performance.)
Presentation in software,
decoding in software.
(Worst case performancewise.
Degraded full-screen
performance.)
Note: AIR 2.5 for TV does not define the VideoStatus class and does not decode H.264 in software. See the
StageVideoEvent class in the ActionScript 3 Reference for details on AIR 2.5 for TV event implementation.
Color spaces
Stage video uses underlying hardware capabilities to support color spaces. SWF content can provide metadata
indicating its preferred color space. However, the device graphics hardware determines whether that color space can
be used. One device can support several color spaces, while another supports none. If the hardware does not support
the requested color space, Flash Player attempts to find the closest match among the supported color spaces.
To query which color spaces the hardware supports, use the StageVideo.colorSpaces property. This property
returns the list of supported color spaces in a String vector:
var colorSpace:Vector. = stageVideo.colorSpaces();
To learn which color space the currently playing video is using, check the StageVideoEvent.colorSpace property.
Check this property in your event handler for the StageVideoEvent.RENDER_STATE event:
Last updated 6/6/2012
No GPU resources are available
to handle video, and nothing is
displayed. Fall back to a Video
object.
(N/A)
518