TweetFollow Us on Twitter

March 93 - SOMEWHERE IN QUICKTIME

SOMEWHERE IN QUICKTIME

TOP 10 QUICKTIME TIPS

JOHN WANG

[IMAGE 031-033_QuickTime_column1.GIF]



To inaugurate this new column on QuickTime, we'll take a look at ten useful tips for QuickTime application developers. This is certainly not an exhaustive list, but itis  an important one.

Here's the list:
10. Working around data reference limitations.
9. Using GetMovieNextInterestingTime.
8. Not calling ExitMovies.
7. Getting a movie's unscaled size.
6. Avoiding the Movie Toolbox when using the standard movie controller.
5. Prerolling a movie for improved playback.
4. Using CustomGetFilePreview with custom dialogs.
3. Conditionally registering a component that requires a hardware device.
2. Detaching a movie controller properly.
1. Calling MaxApplZone from every application.

Some of the tips describe pitfalls that need to be avoided, while others are simply clarifications. Let's take a closer look at each one.

10. Working around data reference limitations.

A current limitation of QuickTime is that each media can have only one data reference to a media data file. This isn't a problem except when you start cutting and pasting between tracks that refer to different media. You'll then be required to copy the media data from one media data file to another. For example, InsertTrackSegment will copy media data between media if the tracks refer to different media.

Calls like GetMediaDataRefCount, AddMediaDataRef, and GetMediaDataRef will reflect the "one data reference" limitation by only accepting index values of 1. You can't replace an existing media data reference in QuickTime 1.0, but you can in QuickTime 1.5, with a new call, SetMediaDataRef. Using this routine is a common way of manuallyresolving media data references that may have been moved by an application. For example, if you move a movie data file onto a different volume, you can update the alias using the Alias Manager and update the data reference for the movie with SetMediaDataRef.

9. Using GetMovieNextInterestingTime.

Since QuickTime is time based rather than frame-number based in the way it deals with temporal video data, a common question is how to get information about movie frames, such as frame rate. The answer is to use GetMovieNextInterestingTime. This function allows you to step quickly and easily through interesting times in a movie. For example, for an estimate of the frame rate of a movie, you could use GetMovieNextInterestingTime to count the total number of frames in the movie and divide it by the total duration of the movie. Likewise, you could use GetMovieNextInterestingTime to identify the 600th frame in a movie. Since the internal data structure of QuickTime movies is optimized for accessing this type of information, GetMovieNextInterestingTime and the other GetNextInterestingTime calls are very efficient.

8. Not calling ExitMovies.

One recommendation that contradicts QuickTime 1.0 documentation is that applications should not call ExitMovies before quitting. QuickTime calls this function at ExitToShell time, and it's safer to allow QuickTime to release private storage and component connections at that time. This prevents problems such as closing components in the wrong order. For example, the proper way to clean up after a movie that uses a standard movie controller is to dispose of the movie controller first, and then dispose of the movie. If done in the reverse order, there may be adverse consequences.

7. Getting a movie's unscaled size.

An application should save the movie box obtained with GetMovieBox when a movie is loaded so that it can retrieve the intended offset and scaling of the movie for playback. However, some applications may also want to get the unscaled size, and there isn't an intuitive way to get it. Since the programmatical effect of calling SetMovieBox is that the movie matrix is changed to reflect the new offset and scaling, you can easily get the movie box for an unscaled movie by setting the movie matrix to the identity matrix; using the utility routine SetIdentityMatrix along with SetMovieMatrix accomplishes this. Then GetMovieBox will return the unscaled size and offsets.

However, there's a loophole. If a track inside the movie is scaled, there may still be scaling in playback since QuickTime supports transformation matrices for movies and for tracks within a movie. Therefore, when working with scaling, applications need to pay attention not only to the movie's scaling but to the tracks' scaling as well.

6. Avoiding the Movie Toolbox when using the standard movie controller.

When using the standard movie controller, you should almost never use any Movie Toolbox routines that control movie playback or change movie characteristics. For example, it would be a mistake to call StartMovie to start playing a movie. Instead, use the movie controller equivalent, MCDoAction with mcActionPlay. Calling StartMovie directly causes the movie to play but with the controller's button in the pause state, not reflecting that the movie is playing back. Similarly, to set looping, you would use MCDoAction with mcActionSetLooping. Bypassing the movie controller by using the Movie Toolbox routines directly on a movie controlled with a movie controller can have dire consequences. As an example, if you set looping for a movie before creating a controller with NewMovieController, you'll cause the Macintosh to crash. Don't let it happen to you!

5. Prerolling a movie for improved playback.

Prerolling can improve playback performance by allowing QuickTime to do preliminary initialization. Since PrerollMovie is passed the movie time and rate, it can fill buffers and caches optimally to prevent initial stuttering. Normally, QuickTime automatically prerolls the movie for you. For example, if you call StartMovie, you don't need to also call PrerollMovie, since StartMovie prerolls the movie for you. The QuickTime 1.5 documentation describing the StartMovie call states this clearly. Likewise, the standard movie controller is optimized to preroll whenever the user starts a movie with the keyboard or mouse. If you call PrerollMovie in these situations, the second PrerollMovie is redundant and will simply waste time. In all other cases, prerolling by calling PrerollMovie is recommended before initiating playback. For example, you should call PrerollMovie before SetMovieRate.

4. Using CustomGetFilePreview with custom dialogs.

If you use CustomGetFilePreview with custom DLOG and DITL resources, you should be aware of a bug with the System 7 pop-up menu CDEF: pop-up menus used in conjunction with black-and- white grafPorts are shifted to the wrong location within the dialog box. The simple workaround is to force the dialog to be a cGrafPort by adding a 'dctb' resource with the same ID as the DLOG and DITL resources. You can easily create a 'dctb' resource with ResEdit by selecting the Custom color button in the DLOG resource template window. For more information on the 'dctb' resource, see the Dialog Manager chapter inInside Macintosh: Macintosh Toolbox Essentials (or in Inside Macintosh Volume V).

3. Conditionally registering a component that requires a hardware device.

If you write a component that requires a hardware device, you should set the wantsRegisterMessage flag to give your component an opportunity to verify that the specific hardware is properly installed. If the hardware isn't available, you can then indicate to the Component Manager that you don't want the component registered. The register routine, called with selector kComponentRegister, should return FALSE if it does want to be registered and TRUE if it doesn't.

One thing to be aware of is that even during registration, the component will be opened with OpenComponent and closed with CloseComponent. Therefore, you can expect OpenComponent before the ComponentRegister routine is called, and CloseComponent after ComponentRegister is called.

For example, if you have a 'vdig' that works with a NuBus video digitizer card, each time that OpenComponent is called you can check whether the hardware is correctly installed, and then return that status when ComponentRegister is called by the Component Manager.

2. Detaching a movie controller properly.

If you want to place the standard movie controller in a different window or location from its usual placement directly below the movie, you must detach the movie controller. Follow these steps:

  1. First bring up the controller by calling NewMovieController with the flag mcNotVisible so that the controller is initially invisible. If you don't do this, the application will momentarily display the controller in the wrong location.
  2. Call MCSetControllerAttached with FALSE to detach the controller.
  3. Call MCSetControllerPort to move the controller to a different port if you want to place it in a different window. If you only want to move the controller in the same window as the movie, you don't have to call MCSetControllerPort.
  4. Call either MCPositionController or MCSetControllerBoundsRect to move the controller to the new location in the port.
  5. Call MCSetVisible to display the controller.

The movie will remain in whatever port it was assigned to using SetMovieGWorld. If MCSetControllerPort isn't called (step 3), the controller will remain assigned to the movie's port when NewMovieController is called.

For example:

SetMovieGWorld(myMovie, (CGrafPtr) myWindow, 0);
mcMC = NewMovieController(myMovie, &movieBounds,
    mcTopLeftMovie + mcNotVisible);
MCSetControllerAttached(mcMC, FALSE);
MCSetControllerPort(mcMC, myOtherWindow);
MCPositionController(myMC, &movieBounds,
    &newControllerRect, mcTopLeftMovie);
MCSetVisible(myMC, TRUE);

1. Calling MaxApplZone from every application.

Not calling MaxApplZone in an application is the reason why many simple QuickTime playback applications play back movies poorly. Because the Memory Manager grows the heap only if there isn't any purgeable or free space left, QuickTime doesn't have the space it needs to play back a movie optimally. Since there's no penalty or drawback for calling MaxApplZone, all applications should call the routine during initialization. In fact, MaxApplZone should be your first Macintosh Toolbox call, because initializing QuickDraw and other managers could allocate memory.

We hope these tips will help you avoid some of the most common pitfalls of QuickTime development. With so many developers writing QuickTime applications and adding QuickTime support into existing applications, we want the journey to be as smooth as possible. We'll keep you updated and informed by continuing to bring you insightful tips and details about QuickTime in this column. Watch for it!


JOHN WANG (AppleLink WANG.JY) is enjoying his youth in the playpen of the Printing, Imaging, and Graphics (PIGs) group in Developer Technical Support at Apple. When he's not engaged in piglet activities, he can be found on a golf course or hogging the road with his Mazda Miata. No one has trouble identifying John's car, since he often cruises the California highways with his dog, Skate. In return, Skate promises to drive safely. *

For more information on the Component Manager, see the QuickTime or System 7.1 documentation on this subject, and see Gary Woodcock and Casey King's article, "Techniques for Writing and Debugging Components," in develop  Issue 12. *



Thanks to the developers who have made this list possible and to Bill Guschwan, Peter Hoddie, and Guillermo Ortiz for reviewing this column. *

 
AAPL
$118.68
Apple Inc.
+1.08
MSFT
$47.91
Microsoft Corpora
+0.44
GOOG
$538.63
Google Inc.
-2.45

MacTech Search:
Community Search:

Software Updates via MacUpdate

RapidWeaver 6.0.3 - Create template-base...
RapidWeaver is a next-generation Web design application to help you easily create professional-looking Web sites in minutes. No knowledge of complex code is required, RapidWeaver will take care of... Read more
iPhoto Library Manager 4.1.10 - Manage m...
iPhoto Library Manager lets you organize your photos into multiple iPhoto libraries. Separate your high school and college photos from your latest summer vacation pictures. Or keep some photo... Read more
iExplorer 3.5.1.9 - View and transfer al...
iExplorer is an iPhone browser for Mac lets you view the files on your iOS device. By using a drag and drop interface, you can quickly copy files and folders between your Mac and your iPhone or... Read more
MacUpdate Desktop 6.0.3 - Discover and i...
MacUpdate Desktop 6 brings seamless 1-click installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on macupdate.... Read more
SteerMouse 4.2.2 - Powerful third-party...
SteerMouse is an advanced driver for USB and Bluetooth mice. It also supports Apple Mighty Mouse very well. SteerMouse can assign various functions to buttons that Apple's software does not allow,... Read more
iMazing 1.1 - Complete iOS device manage...
iMazing (was DiskAid) is the ultimate iOS device manager with capabilities far beyond what iTunes offers. With iMazing and your iOS device (iPhone, iPad, or iPod), you can: Copy music to and from... Read more
PopChar X 7.0 - Floating window shows av...
PopChar X helps you get the most out of your font collection. With its crystal-clear interface, PopChar X provides a frustration-free way to access any font's special characters. Expanded... Read more
Carbon Copy Cloner 4.0.3 - Easy-to-use b...
Carbon Copy Cloner backups are better than ordinary backups. Suppose the unthinkable happens while you're under deadline to finish a project: your Mac is unresponsive and all you hear is an ominous,... Read more
ForeverSave 2.1.3 - Universal auto-save...
ForeverSave auto-saves all documents you're working on while simultaneously doing backup versioning in the background. Lost data can be quickly restored at any time. Losing data, caused by... Read more
Voila 3.8.1 - Capture, annotate, organiz...
Voila is a screen-capture, recording, and annotation tool that is a full-featured replacement for Mac's screen-capture and screen-recording capabilities. It has a large and robust set of editing,... Read more

Latest Forum Discussions

See All

You Can Play the Final Chapter of Lone W...
You Can Play the Final Chapter of Lone Wolf: Dawn Over V’taag Right Now Posted by Jessica Fisher on November 26th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Tales from the Borderland​s Will be Comi...
Tales from the Borderland​s Will be Coming to iOS by the End of the Year Posted by Jessica Fisher on November 26th, 2014 [ permalink ] Telltale Games has announced | Read more »
Sunburn! Review
Sunburn! Review By Campbell Bird on November 26th, 2014 Our Rating: :: DON'T DIE ALONEUniversal App - Designed for iPhone and iPad Platform through the depths of space to make sure your entire crew dies together in this satisfying... | Read more »
Black Friday has Started Early – Lots an...
It’s almost turkey time! Which means lots and lots of food but also lots and lots of sales. Some sales have even started a few days early, which is why we’ve put together a list of iOS games that are currently discounted (sometimes by a lot).... | Read more »
Loose Leaf Review
Loose Leaf Review By Jennifer Allen on November 26th, 2014 Our Rating: :: SIMPLE SKETCHINGiPad Only App - Designed for the iPad Sketch out ideas with simple drawing tools, courtesy of Loose Leaf.   | Read more »
Screeny (Utilities)
Screeny 1.0 Device: iOS iPhone Category: Utilities Price: $.99, Version: 1.0 (iTunes) Description: Screeny is an utility app that helps you save space consumed by screenshots. It screens your camera roll and helps you to filter and... | Read more »
Tilt to Live Bundle Set to Arrive This T...
Tilt to Live Bundle Set to Arrive This Thanksgiving Posted by Ellis Spice on November 25th, 2014 [ permalink ] One Man Left has unveiled an upcoming Tilt to Live bundle, allowing players to get the series for a di | Read more »
BattleLore: Command (Entertainment)
BattleLore: Command 1.0 Device: iOS Universal Category: Entertainment Price: $9.99, Version: 1.0 (iTunes) Description: ***NOTE: Compatible with iPad 2/iPad mini, iPod touch 5 and up and iPhone 4S and up – WILL NOT RUN ON EARLIER... | Read more »
Weather Or Not Review
Weather Or Not Review By Jennifer Allen on November 25th, 2014 Our Rating: :: STYLISH WEATHER REPORTINGiPhone App - Designed for the iPhone, compatible with the iPad Check the weather quickly and conveniently with Weather or Not... | Read more »
The All-New Football Manager Handheld 20...
The All-New Football Manager Handheld 2015 is Available Now Posted by Jessica Fisher on November 25th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »

Price Scanner via MacPrices.net

Early Black Friday MacBook Air sale prices, $...
 MacMall has posted early Black Friday MacBook Air sale prices. Save $101 on all models for a limited time: - 11″ 1.4GHz/128GB MacBook Air: $798 - 11″ 1.4GHz/256GB MacBook Air: $998 - 13″ 1.4GHz/... Read more
Why iPhone 6 Tablet/Laptop Cannibalization Is...
247wallst.com blogger Douglas A. McIntyre noted last week that according to research posted on the Applovin blog site the iPhone 6 is outselling the iPhone 6 Plus by a wide margin . Hardly a surprise... Read more
Worldwide Tablet Growth Expected to Slow to 7...
The global tablet market is expected to record massive deceleration in 2014 with year-over-year growth slowing to 7.2%, down from 52.5% in 2013, according to a new forecast from International Data... Read more
Touchscreen Glove Company Announces New Produ...
Surrey, United Kingdom based TouchAbility specializes in design and manufacture of a wide variety of products compatible with touchscreen devices including smartphones, tablets and computers. Their... Read more
OtterBox Alpha Glass Screen Protectors for iP...
To complement the bigger, sharper displays on the latest Apple devices, OtterBox has introduced Alpha Glass screen protectors to the iPhone 6 and iPhone 6 Plus. The fortified glass screen protectors... Read more
Early Black Friday Mac Pro sale, 6-Core 3.5GH...
 B&H Photo has the 6-Core 3.5GHz Mac Pro on sale today for $3499 including free shipping plus NY sales tax. Their price is $500 off MSRP, and it’s the lowest price available for this model from... Read more
Early Black Friday sale price: 15-inch 2.2GHz...
 B&H Photo has the 2014 15″ 2.2GHz Retina MacBook Pro on sale today for $1699.99. Shipping is free, and B&H charges NY sales tax only. Their price is $300 off MSRP, equalling Best Buy’s price... Read more
13-inch 2.5GHz MacBook Pro (refurbished) avai...
The Apple Store has Apple Certified Refurbished 13″ 2.5GHz MacBook Pros available for $170 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.5GHz... Read more
Early Black Friday iPad mini 3 sale: $75 off...
 Best Buy has iPad mini 3s on sale for $75 off MSRP on their online store for a limited time. Choose free shipping or free local store pickup (if available). Sale prices available for online orders... Read more
Early Black Friday MacBook Pro sale: 15-inch...
 Best Buy has posted early Black Friday prices on 15″ Retina MacBook Pros, with models on sale for $300 off MSRP on their online store for a limited time. Choose free local store pickup (if available... Read more

Jobs Board

*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.