The SoundDescription QuickTime structure contains informations that describe sound samples data.
The QTPlgSoundDesc class provides you with properties and methods that let you whether access or create new instances of such a QuickTime description structure. Also, you can use instances of this class as a convenient container for sound settings that you will use in any way you like it.
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The QTPlgSoundDesc class constructors are called when you create a new instance of the class, while the ˜QTPlgSoundDesc class destructor, is called automatically when the class is no more in use. Also, you can invoke the class destructor by setting the instance of the class to nil.
Once a new class instance is returned, it is good practice to check the class property to be sure that the new object can be used. See the validity requirements for more details.
The class provides you with the following initializer methods:
()
This is the default constructor. Use this constructor to create a completely new data descriptor container in memory
(other as QTPlgSoundDesc)
This is the copy constructor. The properties of the object to be copied will be used to initialize the
new class instance properties
(streamDesc as ,
layout as )
use the properties of the stream of audio data specified by the streamDesc parameter to initialize the properties of the new
QTPlgSoundDesc class instance; also, you can specify an audio channel layout to associate with the sound description by passing
a non nil object into the layout parameter
requires QuickTime 7.0 or later
returns the handle to the sound description structure in use.
useful for toolbox programmers (use with care: you could invalidate the handle causing unpredictable results
(probably an application crash))
specifies a four characters string describing the format of the sound data
specifies the number of sound channels used by the sound sample. Set this property to
1 for monaural sounds; set it to 2 for stereo sounds
specifies the number of bits in each sound sample. Set this field to 8
for 8–bit sound; set it to 16 for 16–bit sound
indicates the rate at which the sound samples were obtained. Sound media handlers use this value to influence
the natural playback speed of the sound described by this sound description structure. The value of this property
represents the number of samples collected per second
specifies the number of samples in each packet. This property has been added to support compression algorithms which can be run at
different compression ratios and to support more generic parsing of QuickTime sound tracks. If this property is not used or the value of the
class property is 0,
its value is always 0
specifies the number of bytes in each packet. This property has been added to support compression algorithms which can be run at
different compression ratios and to support more generic parsing of QuickTime sound tracks. If this property is not used or the value of the
class property is 0,
its value is always 0
specifies the number of bytes in each frame. This property has been added to support compression algorithms which can be run at
different compression ratios and to support more generic parsing of QuickTime sound tracks. If this property is not used or the value of the
class property is 0,
its value is always 0
specifies the number of bytes in each sample. This property has been added to support compression algorithms which can be run at
different compression ratios and to support more generic parsing of QuickTime sound tracks. If this property is not used or the value of the
class property
is 0, its value is always 0
describes the format properties of the stream of audio data associated to this sound description
requires QuickTime 7.0 or later
describes the audio channel layout (if any) associated to this sound description
requires QuickTime 7.0 or later
specifies the data rate in bits per second. Note that this property may not be available for formats that are inherently very variable in bitrate
and highly source–data dependent (such as Apple Lossless)
requires QuickTime 7.0 or later
a localized, human readable string summarizing the sound format as a string
requires QuickTime 7.0 or later