class flash.media.SoundLoaderContext
Available on all platforms
The SoundLoaderContext class provides security checks for files that load
* sound. SoundLoaderContext objects are passed as an argument to the
* constructor and the When you use this class, consider the following security model: load()
method of the Sound class.
*
-
*
- Loading and playing a sound is not allowed if the calling file is in * a network sandbox and the sound file to be loaded is local. *
- By default, loading and playing a sound is not allowed if the calling * is local and tries to load and play a remote sound. A user must grant * explicit permission to allow this. *
- Certain operations dealing with sound are restricted. The data in a
* loaded sound cannot be accessed by a file in a different domain unless you
* implement a URL policy file. Sound-related APIs that fall under this
* restriction are the
Sound.id3
property and the *SoundMixer.computeSpectrum()
, *SoundMixer.bufferTime
, andSoundTransform()
* methods.
*
However, in Adobe AIR, content in the application
security
* sandbox(content installed with the AIR application) are not restricted by
* these security limitations.
For more information related to security, see the Flash Player Developer * Center Topic: <a href="http://www.adobe.com/go/devnetsecurityen" * scope="external">Security.
Instance Fields
var bufferTime:Float
The number of milliseconds to preload a streaming sound into a buffer * before the sound starts to stream. * *
Note that you cannot override the value of
* SoundLoaderContext.bufferTime
by setting the global
* SoundMixer.bufferTime
property. The
* SoundMixer.bufferTime
property affects the buffer time for
* embedded streaming sounds in a SWF file and is independent of dynamically
* created Sound objects(that is, Sound objects created in
* ActionScript).
var checkPolicyFile:Bool
Specifies whether the application should try to download a URL policy file
* from the loaded sound's server before beginning to load the sound. This
* property applies to sound that is loaded from outside the calling file's
* own domain using the Set this property to Sound.load()
method.
* true
when you load a sound from
* outside the calling file's own domain and code in the calling file needs
* low-level access to the sound's data. Examples of low-level access to a
* sound's data include referencing the Sound.id3
property to
* get an ID3Info object or calling the
* SoundMixer.computeSpectrum()
method to get sound samples from
* the loaded sound. If you try to access sound data without setting the
* checkPolicyFile
property to true
at loading
* time, you may get a SecurityError exception because the required policy
* file has not been downloaded.
If you don't need low-level access to the sound data that you are
* loading, avoid setting checkPolicyFile
to true
.
* Checking for a policy file consumes network bandwidth and might delay the
* start of your download, so it should only be done when necessary.
When you call Sound.load()
with
* SoundLoaderContext.checkPolicyFile
set to true
,
* Flash Player or AIR must either successfully download a relevant URL
* policy file or determine that no such policy file exists before it begins
* downloading the specified sound. Flash Player or AIR performs the
* following actions, in this order, to verify the existence of a policy
* file:
-
*
- Flash Player or AIR considers policy files that have already been * downloaded. *
- Flash Player or AIR tries to download any pending policy files
* specified in calls to
Security.loadPolicyFile()
.
* - Flash Player or AIR tries to download a policy file from the default
* location that corresponds to the sound's URL, which is
*
/crossdomain.xml
on the same server as *URLRequest.url
.(The sound's URL is specified in the *url
property of the URLRequest object passed to *Sound.load()
or the Sound() constructor function.)
*
In all cases, Flash Player or AIR requires that an appropriate policy
* file exist on the sound's server, that it provide access to the sound file
* at URLRequest.url
by virtue of the policy file's location,
* and that it allow the domain of the calling file to access the sound,
* through one or more
tags.
If you set checkPolicyFile
to true
, Flash
* Player or AIR waits until the policy file is verified before loading the
* sound. You should wait to perform any low-level operations on the sound
* data, such as calling Sound.id3
or
* SoundMixer.computeSpectrum()
, until progress
and
* complete
events are dispatched from the Sound object.
If you set checkPolicyFile
to true
but no
* appropriate policy file is found, you will not receive an error until you
* perform an operation that requires a policy file, and then Flash Player or
* AIR throws a SecurityError
exception. After you receive a
* complete
event, you can test whether a relevant policy file
* was found by getting the value of Sound.id3
within a
* try
block and seeing if a SecurityError
is
* thrown.
Be careful with checkPolicyFile
if you are downloading
* sound from a URL that uses server-side HTTP redirects. Flash Player or AIR
* tries to retrieve policy files that correspond to the url
* property of the URLRequest object passed to Sound.load()
. If
* the final sound file comes from a different URL because of HTTP redirects,
* then the initially downloaded policy files might not be applicable to the
* sound's final URL, which is the URL that matters in security
* decisions.
If you find yourself in this situation, here is one possible solution.
* After you receive a progress
or complete
event,
* you can examine the value of the Sound.url
property, which
* contains the sound's final URL. Then call the
* Security.loadPolicyFile()
method with a policy file URL that
* you calculate based on the sound's final URL. Finally, poll the value of
* Sound.id3
until no exception is thrown.
This does not apply to content in the AIR application sandbox. Content * in the application sandbox always has programatic access to sound content, * regardless of its origin.
* *For more information related to security, see the Flash Player * Developer Center Topic: <a * href="http://www.adobe.com/go/devnetsecurityen" * scope="external">Security.
function new(?bufferTime:Float, ?checkPolicyFile:Bool):Void
Creates a new sound loader context object. * *
bufferTime | The number of seconds to preload a streaming sound * into a buffer before the sound starts to stream. * |
checkPolicyFile | Specifies whether the existence of a URL policy
file should be checked upon loading the object
( |