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. *

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

f.lux 39.984 - Adjusts the color of your...
f.lux makes the color of your computer's display adapt to the time of day, warm at night and like sunlight during the day. Ever notice how people texting at night have that eerie blue glow? Or wake... Read more
Merlin Project 4.2.7 - $289.00
Merlin Project is the leading professional project management software for OS X. If you plan complex projects on your Mac, you won’t get far with a simple list of tasks. Good planning raises... Read more
Sound Studio 4.8.10 - Robust audio recor...
Sound Studio lets you easily record and professionally edit audio on your Mac. Easily rip vinyls and digitize cassette tapes, or record lectures and voice memos. Prepare for live shows with live... Read more
Google Chrome 60.0.3112.101 - Modern and...
Google Chrome is a Web browser by Google, created to be a modern platform for Web pages and applications. It utilizes very fast loading of Web pages and has a V8 engine, which is a custom built... Read more
Microsoft Office 2016 15.37 - Popular pr...
Microsoft Office 2016 - Unmistakably Office, designed for Mac. The new versions of Word, Excel, PowerPoint, Outlook and OneNote provide the best of both worlds for Mac users - the familiar Office... Read more
Sketch 46.2 - Design app for UX/UI for i...
Sketch is an innovative and fresh look at vector drawing. Its intentionally minimalist design is based upon a drawing space of unlimited size and layers, free of palettes, panels, menus, windows, and... Read more
beaTunes 5.0.4 - Organize your music col...
beaTunes is a full-featured music player and organizational tool for music collections. How well organized is your music library? Are your artists always spelled the same way? Any R.E.M. vs REM?... Read more
Yasu 4.0.4 - System maintenance app.
Yasu was created with system administrators who service large groups of workstations in mind, Yasu (Yet Another System Utility) was made to do a specific group of maintenance tasks quickly within a... Read more
NetNewsWire 4.0.4 - RSS and Atom news re...
NetNewsWire is the best way to keep up with the sites and authors you read most regularly. Let NetNewsWire pull down the latest articles, and read them in a distraction-free and Mac-like way. Native... Read more
Chromium 60.0.3112.101 - Fast and stable...
Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all Internet users to experience the web. Version 60.0.3112.101: Release notes were unavailable... Read more

5 reasons why 2v2 is the best mode in Cl...
Supercell has been teasing fans with 2v2 windows that allow players to team up for limited periods of time. The Summer of 2v2 was just this past July, but players are already clamoring for more of that sweet, sweet team-based action. The fans have... | Read more »
The best deals on the App Store this wee...
It seems like the week's only just started, and yet here we are with a huge pile of discounted games to sort through. There are some real doozies on sale this week. We're talking some truly stellar titles. Let's take a look at four of the best... | Read more »
Cat Quest Guide - How to become a purrfe...
Cat Quest is an absolutely charming open-world RPG that's taken the gaming world quite by storm. This game about a world populated by furry kitty warriors is actually a full-length RPG with sturdy mechanics and a lovely little story. It's certainly... | Read more »
Silly Walks Guide - How to strut your st...
Silly Walks is an all new adventure game that lives up to its name. It sees you playing as a variety of snack foods as you teeter-totter your way to rescue your friends from the evil blender and his villainous minions. It's all very . . . well... | Read more »
The best mobile point-and-click adventur...
Nostalgia for classic point-and-click adventure games has reached an all-time high in recent years, and the rise of mobile games have provided a perfect platform for this old-school genre. This week we're going to take a look at some of the best... | Read more »
Titanfall: Assault Beginner's Guide...
Respawn's dazzling mech battler Titanfall has gotten its first mobile game at long last -- Titanfall: Assault. Assault transforms that parkour FPS action into a card battler not dissimilar to Clash Royale. Titanfall: Assault isn't just another... | Read more »
Unobstruct (Utilities)
Unobstruct 1.0 Device: iOS Universal Category: Utilities Price: $.99, Version: 1.0 (iTunes) Description: You’re already reading web pages on a pretty small screen. Don’t let floating social media sharing toolbars and the like get in... | Read more »
Burgle Bros (Games)
Burgle Bros 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Burgle Bros requires stealth, planning and a little bit of luck. In the tradition of classic heist movies like Ocean's 11 and The... | Read more »
The best new games we played this week -...
The hits continue to come fast and strong this month, as August welcomes in game after game, many of them of very high quality. It's been another busy week, but we're not complaining. This week saw the arrival of some of the best mobile games... | Read more »
CSR Racing 2: How to master Live Races
Getting better at racing the AI in CSR Racing 2 is a pretty straightforward process. You run enough races with a particular car to get its shift timing down, continually improve it by buying upgrades whenever you can, and add any fusion parts you... | Read more »

Price Scanner via MacPrices.net

Samsung Electronics Launches New Portable SSD...
Samsung Electronics America, Inc. has announced the launch of Samsung Portable SSD T5 – its newest portable solid state drive (PSSD) that raises the bar for the performance of external memory... Read more
TrendForce Reports YoY Gain of 3.6% for 2Q17...
Market research firm TrendForce reports that the global notebook shipments for this second quarter registered a sequential quarterly increase of 5.7% and a year-on-year increase of 3.6%, totaling 39.... Read more
Sale! 10-inch iPad Pros for $50 off MSRP, no...
B&H Photo has 10.5″ iPad Pros in stock today and on sale for $50 off MSRP. Each iPad includes free shipping, and B&H charges sales tax in NY & NJ only: – 10.5″ 64GB iPad Pro: $599, save $... Read more
Sale! 2017 13-inch Silver 2.3GHz MacBook Pro...
Amazon has new 2017 13″ 2.3GHz/128GB Silver MacBook Pro on sale today for $100 off MSRP including free shipping. Their price is the lowest available for this model from any reseller: – 13″ 2.3GHz/... Read more
WaterField Unveils Collaboratively-Designed,...
In collaboration with customers and seasoned travelers, San Francisco maker WaterField Designs set out to create the preeminent carry-on system to improve the experience of frequent fliers. The... Read more
Miya Notes Mac-Client for Google Keep (Launch...
MacPlus Software has announced te launch of Miya Notes for Google Keep 1.0, a powerful Mac-client for Google Keep. Millions of people use Google Keep on their phones and online, but a convenient Mac... Read more
Apple refurbished iMacs available starting at...
Apple has previous-generation Certified Refurbished 2015 21″ & 27″ iMacs available starting at $849. Apple’s one-year warranty is standard, and shipping is free. The following models are... Read more
2017 13-inch MacBook Airs on sale for $100 of...
B&H Photo new 2017 13″ MacBook Airs on sale today for $100 off MSRP, starting at $899: – 13″ 1.8GHz/128GB MacBook Air (MQD32LL/A): $899, $100 off MSRP – 13″ 1.8GHz/256GB MacBook Air (MQD42LL/A... Read more
12-inch MacBooks on sale for $100 off MSRP
Amazon has 2017 12″ Retina MacBooks on sale for $100 off MSRP. Shipping is free: 12″ 1.2GHz Space Gray MacBook: $1199.99 $100 off MSRP 12″ 1.2GHz Silver MacBook: $1198 $101 off MSRP 12″ 1.2GHz Gold... Read more
KuGi Lightweight Stand And Portfolio Case Wit...
This briefcase style embedded keyboard design gives Apple iPad Pro 10.5-inch high-end atmosphere at a low-end price. The ultra-thin lightweight design makes it convenient to carry and provides all-... Read more

Jobs Board

SW Engineer *Apple* TV - Apple Inc. (United...
Job Summary The Apple TV team is looking for an experienced engineer with a passion for delivering first in class home entertainment solutions. The candidate will Read more
Development Operations and Site Reliability E...
Development Operations and Site Reliability Engineer, Apple Payment Gateway Job Number: 57572631 Santa Clara Valley, California, United States Posted: Jul. 27, 2017 Read more
Frameworks Engineering Manager, *Apple* Wat...
Frameworks Engineering Manager, Apple Watch Job Number: 41632321 Santa Clara Valley, California, United States Posted: Jun. 15, 2017 Weekly Hours: 40.00 Job Summary Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Solutions Consultant - Apple Inc. (U...
Job Summary As an Apple Solutions Consultant, you'll be the link between our future customers and our products. You'll showcase your entrepreneurial spirit as you Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.