Flash Media Handler

QT Events

The first new QT Event is

kQTEventKey = FOUR_CHAR_CODE('key ')

The key event parameters are as follows:

    qtevent.param1: key

    qtevent.param2: modifiers

    qtEvent.param3: scanCode

The second new QT Event is

kQTEventMouseMoved = FOUR_CHAR_CODE('move'),

which indicates that the mouse has moved. There are no parameters other than the location.

The new version 2 format of the QT Event record is shown next:

struct QTEventRecord {

    long        version;    /* version is 2 for the new format */

    OSType      eventType;

    Point       where;

    long        flags;

    long        payloadRefcon; /* fields from here down only present

                                if version >= 2*/

    long        param1;

    long        param2;

    long        param3;

};

Note that the value of the version field indicates the format of the record. If it is 2, then the record is in the new format.

Importing a Flash Movie

The Flash importer sets the following settings by default in order to simulate the playback experience in the Flash player. This should work for most of the time, but it may be necessary to change some of them to suit your needs. It is recommended to review these options before you save your imported Flash movie as a QuickTime movie.

• The Auto Play flag is on, meaning the movie will play as soon as it is opened (same as in QuickTime 4).

• The Loop flag is on, meaning the movie will play repeatedly (same as in QuickTime 4).

• The Play All Frames is on in QuickTime Player. With this option on, QuickTime Player renders every frame of the Flash movie with the rate of the movie set to zero (same as in QuickTime 4).

Also, if the Flash movie contains “streaming sound” (Macromedia’s term for running sound as opposed to short sound triggered by an event), the Flash media handler drops frames in order to catch up with the sound playback, even if the Play All Frame is on (new to QuickTime 5.)

Apple has addressed the issue of having multiple Flash tracks with text fields. The effects of the change are:

• You can navigate through text fields not only in a single Flash track, which you can do now.

• In addition, if you have more than one Flash tracks with a text field, hitting the Tab key will take you to the next Flash track instead of rotating over to the first field in the same track. Shift-tab works as well but goes backward.

Adding Wired Actions To a Flash Track

The sample code on the QuickTime SDK, AddFlashActions, provides the code you need to add wired actions to a Flash track. It may also be useful to download the Macromedia SWF File Format Specification at http://www.macromedia.com/software/flash/open/spec/, as well as the SWF File Parser code at the Macromedia Web site.

This section explains the steps you need to follow in order to add wired actions to a SWF 3.0 file.

Extending the SWF Format

QuickTime 4 extends the SWF file format to allow the execution of any of its wired actions, in addition to the much smaller set of Flash actions. For example, you may use a SWF file as a user interface element in a QuickTime movie, controlling properties of the movie and other tracks. QuickTime also allows SWF files to be compressed using the zlib data compressor. This can significantly lower the bandwidth required when downloading a SWF file when it is in a QuickTime movie.

By using wired actions within a Flash track, compressing your Flash tracks, and combining Flash tracks with other types of QuickTime media, you can create compact and sophisticated multimedia content.

The SWF File Format Specification consists of a header followed by a series of tagged data blocks. The types of tagged data blocks you need to use are the DefineButton2 and DoAction. The DefineButton2 block allows Flash actions to be associated with a mouse state transition. DoAction allows actions to be executed when the tag is encountered. These are analogous to mouse-related QT event handlers and the frame loaded event in wired movies.

Flash actions are stored in an action record. Each Flash action has its own tag, such as ActionPlay and ActionNextFrame. QuickTime defines one new tag: QuickTimeActions, which is 0xAA. The data for the QuickTime actions tag is simply a QT atom container with the QuickTime wired actions to execute in it.

There are also fields you need to change in order to add wired actions to a SWF file. Additionally, there is one tag missing from the SWF file format that is described below.

What You Need to Modify

For defineButton2, you need to modify or add the following fields: file length, action records offset, the action offset, the condition, the record header size portion, and add action record.

File Length

A 32-bit field in the SWF file header.

RecordHeader for the defineButton2

RecordHeader contains the tag ID and length. You need to update the length. Note that there are short and long formats for record headers, depending on the size of the record. The tag ID for defineButton2 is 34.

ActionRecordsOffset

The action records offset, a 16-bit field, is missing from the SWF File Format Specification. It occurs between the flags and buttons fields. It is initially set to 0 if there are no actions for the button. If there are actions for the button, then it must contain the offset from the point in the SWF file following this 16-bit value to the beginning of the action offset field.

    DefineButton2 =

        Header

        ButtonID

        Flags

        ActionRecordsOffset     (this is missing from the spec)

        Buttons

        ButtonEndFlag

        Button2ActionCode

        ActionOffset

        Condition

        Action          [ActionRecords]

        ActionEndFlag

ActionOffset

There is one action offset per condition (mouse overDownToIdle). This is the offset used to skip over the condition and the following actions (the ActionRecord) for the condition. You need to update this value when adding actions.

Condition

The condition field is roughly equivalent to a wired movie event. The actions associated with button state transition condition are triggered when the transition occurs. You need to add or edit this field.

Actions

Flash actions each have their own action tag code. QuickTime actions use a single QuickTime actions code: 'AA'. You may add a list of actions to a single QuickTime actions tag.

The format of the QuickTime actions tag is as follows:

    1 byte:     // Tag = 'AA'

    2 bytes:    // data length (size of the QTAtomContainer)

    n bytes     // the data which is the QTAtomContainer holding the

                // wired actions

DoAction

For DoAction, you need to modify a subset of the defineButton2 fields in the same manner as described above. These fields are file length, the record header size portion, and the action record.

Note that you need to write the length fields in little-endian format.

< Previous PageNext Page > Hide TOC